Document b5LxJrOYKE3V3Xko43eKqkQdg

FILE NAME Brakes BRK DATE 1989 Aug DOC BRK131 DOCUMENT DESCRIPTION NIOSH Report - Control of Asbestos Exposure During Brake Drum Service CONTROL OF ASBESTOS EXPOSURE DURING BRAKE DRUM SERVICE John W. Sheehy Ph.D. P.E. C.I.H. Thomas C. Cooper Dennis M. O'Brien Ph.D. P.E. C.I.H. James D. McGlothlin Ph.D. Phillip A. Froehlich U. S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service Centers for Disease Control National Institute for Occupational Safety and Health Division of Physical Sciences and Engineering Cincinnati Ohio 45226 August 1989 DISCLAIMER Mention of company names < products does not constitute endorsement by the National Institute for Occupational Safety and Health DHHS NIOSH Publication No. 89-121 For sale by the Superintendent of Documents U.S. Government Printing Office Washington D.C. 20402 ii ABBREVIATIONS CDC Centers for Disease Control cfm Cubic feet per minute CFR Code of Federal Regulations ate DHEW Department of Health Education and Welfare ri DHHS Department of Health and Human Services ECTB Engineering Control Technology Branch a se EDXA Phat se EPA dispersive ray analysis Environmental Protection Agency co Fibers per cubic centimeter ig Rae m Fibers per cubic meter Sat: # oes held aerosol monitor aaa HEPA High efficiency particulate air LOD Limit of detection Lpm NIOSH OSHA -- ---- PEL REL SAED TEM TWA Liters per minute National Institute for Occupational Safety and Occupational Safety and Health Administration Phase contrast microscopy Permissible exposure limit Recommended exposure limit Selected area electron diffraction Transmission electron microscope or microscopy weighted average Health iii ABSTRACT Earlier studies of airborne asbestos exposures to mechanics during brake maintenance operations showed overexposure to asbestos fibers during brake servicing especially brake assembly cleaning Because an estimated 150,000 brake mechanics and garage workers in the U.S. are potentially exposed to asbestos a known carcinogen and the lack of information available on the effectiveness of available controls an evaluation of these methods was initiated Detailed field surveys were conducted five methods for controlling exposure to asbestos at five facilities employing during brake repair These included the use of two commercial enclosure devices with ventilation provided by a HEPA equipped vacuum a HEPA equipped vacuum alone a brush with recirculating cleaning solution and cleaning solvents in aerosol cans These controls were evaluated while servicing brakes to automobiles pickup trucks vans and vehicles with a wheel rear axle Detailed evaluations of these control measures involved a program consisting of traditional air sampling methods incorporating phase contrast microscopy PCM and transmission electron microscopy TEM and time analysis of brake dust exposure Personal and area air samples were collected during brake repair to each vehicle The TEM results include asbestos fibers of all lengths The airborne asbestos concentrations experienced by auto mechanics while using various control methods were determined from the personal and source samples Personal sample results for the brake mechanics show that concentrations using PCM analysis ranged from less than 0.004 to 0.016 cc below the NIOSH recommended exposure limit REL of 0.1 All cc exposures were using PCM analysis Analyses by TEM indicated the presence of asbestos fibers not detected by PCM but at levels well below 0.1 cc for maintenance operations involving small to medium size vehicles The highest measured exposures as determined by TEM were found for workers servicing heavy duty trucks Fibers in the wheel drum bulk samples represented less than 1 percent of the brake results dust from used less but were generally 60 to 100 percent chrysotile Based on the this study all the devices tested in combination with the work practices controlled the mechanic's asbestos exposure during brake servicing to than the OSHA PEL and the NIOSH REL to asbestos The personal exposures determined in this study were much lower than those reported in the literature for brake service operations involving the use of compressed air and brush cleaning Recommendations for improved work practices as well as suggested modifications to the control systems are presented iv CONTENTS Disclaimer . 2... 1... ee ii Abbreviations Abstract 2. 6 . 2... 6. ee 2... ee ee ee ee ee ee iii iv Acknowledgments . 2... 1. ee ee ee ee ee. viii 1 Introduction . 1 1.1 Historical Development of Friction Products for Vehicular Brakes 2 1.2 Requirements for Brake Linings . 3 1.3 Brake Service Operations and Control Methods 4 1.3.1 History of Brake Lining Repair and Maintenance 4 1.3.2 Current Brake Repair Practices and Control Methods 5 2 Potential Health Hazards and Exposure Criteria 66 2.1 Toxic Effects . 66 2.1.1 Asbestos 6 2.1.2 Solvents 7 2.2 Exposure Criteria . . . 7 2.2.1 OSHA Permissible Exposure Limit . ~~ 2.2.2 NIOSH Recommended Exposure Limit ~~ 3 Methodology . 9 3.1 Overview 9 3.2 Site Selection Ce 9 3.3 Depth Surveys . Ce 9 3.3.1 Air Sampling and Analysis Ce 10 3.3.2 Ventilation Lo. 222 3.3.3 Ergonomic Evaluation of Brake Maintenance and Repair Lo 222 3.3.4 Time Sampling ............... 0.04. 222 4 Control Methods and Facility Sites Surveyed ....... 2... 4.1 Vacuum Enclosure A .. . ee 4.1.1 Control Description ..............2.4.24;, 4.1.2 Facility Description ................., 4.2 Vacuum Enclosure B . 2... eee ee 4.2.1 Control Description ........ 2.002. 04% 4.2.2 Facility Description ..............0.04802. 4.3 Vacuum Only . Ce 4.3.1 Control Description Ce 4.3.2 Facility Description ............. 4.2248. 4.4 Wet Recycle . 2... ee ee 4.4.1 Control Description ...............2.4. 4.4.2 Facility Description ...............202.2. 14 14 14 18 19 19 22 24 24 24 27 27 29 aici 4.5 Aerosol Spray Loe 4.5.1 Control Description 4.5.2 Facility Description . 4.6 Rudimentary Controls and No Controls Results . . 5.1 Asbestos Concentrations as Determined by PCM . 5.2 Asbestos Concentrations as Determined by TEM . 5.2.1 Personal Sampling Results Source Sampling Results 5.2.25.2.25.2.3 5.2.65.2.6 5.2.6 Background Sampling Results Outdoor Ambient Sampling Results Bulk and Settled Dust Samples Field Blanks 5.3 5.4 Large Vehicles . Time Sampling Results Discussion . Performance 6.1 Control Loe ee 6.1.1 6.1.2 6.1.3 6.1.4 Comparison to Historical Data Ambient Levels Comparison to No Controls Lo Comparison to Indoor and Outdoor Effect of Vehicle Type Drum Size and Number of Drum Brakes 6.2 Control Method Design Strengths and Weaknesses 6.2.1 6.2.1 6.2.2 Vacuum Enclosures Vacuum Only . 6.2.3 6.2.46.2.4 Wet Recycle Aerosol Spray Regulatory Agencies 6.3 Recommendations of . 6.3.1 6.3.1 Occupational Safety and Health Administration 6.3.2 6.3.2 U.S. Environmental Protection Agency . 6.4 6.5 6.6 Time Sampling . . Work Practices and Hygiene Fiber Size and Potential Health Effects Recommendations 7.1 Conclusions 7.2 Recommendations 7.2.1 Engineering Controls and Work Practices 7.2.2 Training and Education . 7.2.3 7.2.4 Sanitation . . Protective Clothing and Respiratory Protection . References 2223 2223 2223 2223 34 34 37 37 37 40 40 40 44 44 44 49 49 49 51 51 52 52 52 54 54 55 55 55 56 57 57 59 61 61 63 63 64 65 65 66 vi FIGURES 4-24-1 4-1 Enclosure A glove box and filter assembly 17 4-2 4-2 Layout of garage with enclosure A 20 4-3 4-3 Vacuum enclosure B system . 21 4-4 4-4 Layout of garage with enclosure B. 23 4-5 4-44-5 Vacuum with HEPA filter 25 4-6 4-6 Layout of garage with vacuum . 26 4-7 Wet recycle system . 28 4-7 recycle 4-8 Layout of garage with wet 30 4-24-94-9 Aerosol Sprayer 31 5-1 PCM fiber concentrations 3326 exposure TEM 5-2 Arithmetic vs geometric mean asbestos 3326 Personal vs background asbestos levels TEM 3326 5-1 5-45-4 Asbestos exposures Large trucks vs smaller vehicles 3326 6-2 6-2 personal samples 6-1 Fiber exposures by PCM 0 Fiber size distribution for all 60 TABLES 4.1 4.1 Facility Description 15 4-2 Vehicle Description 16 5-1 5-1 5-3 5-2 5-4 5- 5- 5-5 5-7 Personal Sample Fiber Concentrations by Control Method PCM 35 Source Sample Fiber Concentrations PCM | 35 Personal Sample Asbestos Concentrations by Control Method TEM 38 Source Sample Asbestos Concentrations TEM . 38 Asbestos Ambient Concentrations as Determined by TEM . 41 TEM Analysis of Bulk Brake and Settled Dust Samples . 43 Asbestos and Fiber Concentrations During Servicing Large Drum Brakes 45 Average Relative Respirable Dust Levels in millivolts 48 Appendix Fiber Counts on Filter Blanks 70 vii ACKNOWLEDGMENTS We thank the following individuals who assisted with the sampling surveys Frank Godbey Harold Van Wagenen Michael Gressel James Gideon William Todd Karen Lenihan Paul Hentz and Cliff Kohlmeyer of NIOSH and Tom Weems of PEI Inc. We especially thank Eugenia Shtrom of PEI who performed the TEM microscopy and Data Chem for the PCM analysis We appreciate the excellent cooperation of personnel from the Ohio Department of Transportation 8th District Garage the U.S. Post Office Maintenance Facilities in Nashville Tennessee and Louisville Kentucky the Cincinnati Bell Telephone Company and the Cincinnati Gas and Electric Company In addition we thank Mr. Vinay Kumar and Mr. Steve Shapiro Washington D.C. for of the U.S. Environmental Protection Agency their technical guidance and support in this study This study was supported under Interagency Agreement No. Chemical Engineering Branch Office of Toxic Substances Protection Agency DW75931956-01 with U.S. Environmental the viii 1 INTRODUCTION Under the Occupational Safety and Health Act of 1970 the National Institute for Occupational Safety and Health NIOSH has been given a number of responsibilities including the identification of occupational safety and health hazards evaluation of these hazards and recommendation of standards to regulatory agencies to control the hazards Located in the Department of Health and Human Services formerly DHEW NIOSH conducts research separate from the standard setting and enforcement functions conducted by the Occupational Safety and Health Administration OSHA in the Department of Labor An important area of NIOSH research deals with methods for controlling occupational exposure to potential chemical and physical hazards The Engineering Control Technology Branch ECTB of the Division of Physical Sciences and Engineering has been given the lead within NIOSH to study the engineering aspects relevant to the control of these hazards in the workplace NIOSH has been instrumental in the development of recommendations for safeguarding workers safety and health from exposure to occupational hazards Since 1976 ECTB has conducted assessments of health on the basis of industry common industrial process hazard control technology or specific control techniques The objective of each of these studies has been to document and evaluate control potential health techniques hazards in and to determine their effectiveness in reducing an industry or at specific processes These data are used to create a greater awareness of the need for or availability of an effective system of hazard control measures This research effort involves a series of through surveys of selected manufacturing plants or processes and an assessment of those that have been designed to effectively control exposure or minimize safety related hazards Emphasis is placed on identifying concepts in design which can be transferred to other similar processes Next depth surveys are conducted to determine the control parameters and their effectiveness on preventing a health risk The reports from these depth surveys are used as a basis for making control recommendations in NIOSH policy documents and preparing technical reports and journal articles on the effectiveness hazards This information is part of of designs and techniques for controlling a data base available to health professionals equipment manufacturers and others to assist in the development of effective control measures in the workplace Asbestos is used because airborne in the manufacture of vehicular brake asbestos exposure to workers has been materials associated however with an increased risk for cancer other materials have been substituted for asbestos in the fabrication of friction materials used in brakes However asbestos is i a hon tk an_, ~ - e,a RIE - a yte eS slTote SRN still a component in a majority exposure during maintenance and model vehicles of brakes and there is replacement of brakes a potential for asbestos especially on older A research and Wegmcoanntrol Dubrow and priority assessment of occupational carcinogens by identified occupations with potentially high cancer risk by combining the results of 12 major occupational disease surveillance studies On the basis of these results and analysis of other available epidemiologic industrial hygiene toxicologic and employment data recommendations were made concerning priorities for occupational cancer research and control Their results pointed to asbestos as the number one priority requiring further investigation of methods to control exposure In this situation where occupational disease surveillance studies point to a likely problem with a known carcinogenic agent the priority should be placed on industrial hygiene investigations of asbestos exposure in the suspect occupations If likely exposure is found control measures should be developed and instituted There are frequent asbestos exposures during vehicle brake maintenance From data contained in the National Occupational Hazard Survey NIOSH estimates that a work force of are potentially at least 155,000 asbestobsrake exposed to mechanics ) Because and garage workers in the of the large number of workers potentially exposed and the limited data on asbestos exposures U.S. associated with these occupations a study was initiated to assess the effectiveness of controls used during the servicing of vehicular brakes The vast majority of the affected workers are employed by small businesses that lack the resources necessary to evaluate these devices The objective of this study was to identify evaluate and document technology used to control exposure to asbestos in the vehicle brake drum service industry This was accomplished by determining airborne concentrations of asbestos experienced by auto mechanics while using various control techniques during maintenance and replacement of drum brakes The study focused primarily on vehicles with brake drum sizes of 12 inches or less The maintenance of disc brakes was not evaluated in the study because the quantity of dust generated and retained by these systems is minimal and thus thought to represent a lesser potential for creating an exposure to asbestos ten BRAKES fe 1.1 HISTORICAL DEVELOPMENT OF FRICTION PRODUCTS FOR VEHICULAR 3 Early passenger cars were light and operated at low speeds Brake materials included leather impregnated cotton wool and felt In 1903 woven asbestos friction Pennsylvania the Mattison materials were first Company of Ambler marketed in ( United States by the Keasbey Because of the superior heat resistance and durability woven asbestos brakes soon dominated the market and and continued to be the predominant product used in automobiles until about 1930 They typically contained 70 percent or more cored asbestos yarn impregnated with drying oils and bituminous material Molded brake linings were developed in the early 1920's and gained increasing use with the introduction of internal shoe brakes in 1927. By 1940 virtually all automobiles were equipped with molded brake linings although the use of woven products continued in trucks heavy equipment and for specialized applications The molded linings were usually cut to length by the manufacturer and mounted onto the brake shoes with rivets Until the mid 1920's brakes were only mounted on rear wheels however with the development of internal shoes four wheel braking systems soon became standard As automobiles were manufactured for use at higher speeds brake linings were improved in both quality and performance Various new materials were introduced as fillers binders and friction modifiers Bonded brake linings were developed in 1948 and soon accounted for approximately 40 percent of the original equipment brake market They also rapidly dominated the replacement market because of the considerable savings in labor during installation In 1965 the first disc brakes were introduced on American automobiles and by 1975 virtually all original equipment cars had front wheel brakes of this type However because of less stringent braking requirements and the difficulty of adapting mechanical parking brakes to the disc configuration the rear wheel brakes on 95 percent of cars sold in early 1980's were of the drum variety 1.2 REQUIREMENTS FOR BRAKE LININGS A wide variety of ingredients are commonly used automobile brake linings to achieve the desired of in the manufacture friction properties 5-8 5-8 These include asbestos organic binders friction modifiers fillers and curing agents Asbestos is used for fiber reinforcement flexibility and heat resistance Chrysotile is used almost exclusively and comprises from 40 to 50 percent of the brake lining Amosite crocidolite or other amphibole asbestos varieties are not used because they are too harsh and tend to score the brake drums The lining should be nonabrasive to the drum surface In addition to causing rapid drum wear abrasive linings score the drums the wear of the lining Brake drums are commonly which in turn exacerbates made of cast iron and steel Steel drums are more susceptible to scoring During braking chemical and physical changes occur in the material at the braking surfaces decrease fade in These changes may friction Brakes produce an increase build with satisfactory linings fade or a slightly repeat upon cooling. applications but return to their initial state Ideally the desired frictional qualities should throughout the life of the lining material upon be maintained Low wear of the linings is desirable for economical and practical considerations however if the resistance is too low excessive pedal pressure may be required On the other hand high wear resistance linings have a tendency to glaze This can be overcome if the brake lining surface can be renewed Pyrolysis of the organic binders and thermal decomposition of the chrysotile renewal of fibers under braking the lining surface conditions provide the necessary continual Other necessary or desirable properties of brake linings include physical strength dimensional stability quiet operation and safe and nonoffensive degradation products Of the properties desired in the linings greatest attention is paid to build fade and recovery characteristics Various studies show that brake dust consists of 0.004 to 30 percent asbestos with the by weight vast majority of the samples containing less than 5 percent optical 18 10-13 asbestos When these samples were analyzed by optical and electron microscopy a majority of the asbestos fibers were less than 5 ...m in length One 75 percent of asbestos fibers were less than study showed 0.3 ...m in length Another showed 80 of chrysotile fibers = percent from brake drums were less than 0.4 ...m long = 1.3 BRAKE SERVICE OPERATIONS AND CONTROL METHODS 1.3.1 3 History of Brake Lining Repair and Maintenance The evolution of brake lining materials led to changes in work practices which affected brake mechanics exposure to asbestos From 1920 until about 1930 E when braking was done through the use of external brake bands made from woven :q materials the predominant exposure to asbestos was due to the cutting and fitting of the woven lining material It is speculated that the airborne fiber : concentrations during this period were considerably less than those which F occurred later when machining of molded materials was common From 1927 when internal brake shoes with molded linings were developed until 1948 when bonded brake linings were introduced internal brake linings were attached to shoes using rivets The lining material for use in the replacement market was supplied in large rolls or as segments cut to appropriate size Most of the cut segments were drilled at the factory for rapid mounting on 3 the shoes In some circumstances however drilling for the rivets and a bevelling were done by the mechanic installing them The use of rolled linings required cutting the friction material to shape drilling holes for rivets and bevelling the edges appropriately These practices contributed significantly iY to the asbestos exposure to workers Even when shoes with drilled and bevelled linings were installed the processes of punching out the rivets holding the old lining and riveting the new lining to the shoes gave rise to asbestos ; a exposures With the introduction of bonded linings the need for drilling facing or grinding operations during installation decreased significantly However for a short period of time in the mid 1950's when automobile brake shoes were first on uniform thickness installed with a fixed anchor some tapering was necessary bonded linings to achieve a proper fit Previously the end of the shoe opposite to that of Shortly thereafter the hydraulic cylinder tapered bonded linings could be mechanically adjusted were available from the factory Subsequent to 1960 considerably fewer bevelling or performed by an automobile mechanic replacing brake grinding linings operations were During replacement of internal shoe brakes a common practice was to remove the brake wear dust from the housing by compressed air or brushing After 1970 aoe because of increasing awareness of the hazards of asbestos and its presence in re brake lining dust some brake servicing facilities changed to work practices which included wet or dry brushing wet wiping or vacuuming , In the 1930's and 1940's most automobile shops were relatively small mechanics performed all automobile maintenance and repair activities and In most recent years however there has been an increasing tendency towards specialization and the establishment of shops for brake and front end work exclusively Although asbestos exposures during brake work on an individual vehicle may be less than those of previous years workers who perform brake repairs in these franchised volume shops are exposed for considerably longer periods of time 1.3.2 Current Brake Repair Practices and Control Methods Repair facilities from small service stations to fleet garages follow similar brake servicing procedures A vehicle is driven into a repair stall or bay for a brake system examination the wheels are elevated removed and the brake assembly is inspected Loose dust is cleaned from the drums and brake assemblies by vacuuming wet or dry brushing blowing with compressed air or a combination of these methods At the time of this study however most brake servicing facilities used wet brushing wet wiping bottle wash or high efficiency particulate air HEPA filtered vacuum cleaning systems Parts are then replaced or repaired as needed and the brake system is reassembled and adjusted Test driving the vehicle for proper fitting and adjustment is the final phase of the servicing operation During these brake servicing operations the brake repairman and other service personnel in the garage area are potentially exposed to asbestos dust at all times during and following the brake drum removal If the normal dust buildup inside the drum and brake assembly is removed and disposed of in a controlled manner these exposures can be minimal DF e 42 tain ot - PURE pt 2 POTENTIAL HEALTH HAZARDS AND EXPOSURE CRITERIA 2.1 TOXIC EFFECTS 2.1.1 Asbestos of chrysotile The potential health effects from the inhalation include asbestosis lung cancer and mesothelioma chrysotile asbestos fibers In a detailed examination of 90 New capaciwtorykerg or more years of shop York City union motor vehicle maintenance work 29 percent had decreased vital with 10 , Many of the workers examined showed signs consistent with asbestosis with observed changes noted in chest rays and indications of restrictive respiratory disease The prevalence of these changes was significantly higher 19 20 years from the onset of auto work a result frequently workers who have had occupational exposure to asbestos experienced by other Chrysotile asbestos fibers exist in automobile brake dust in various states of deformation due to the chemical degradation at the high temperatures encountered during use Unlike chrysotile the health effects from exposure to forsterite a deformation product of chrysotile or to transition series ystalline structures fibers chrysotile with altered documented In studies by Davis and Coniam and Koshi structures are not ) in which well fibers of chrysotile chrysotile and forsterite were injected into the pleural and peritoneal cavities of mice the results suggested varying of toxic degrees et al , effects and Davis Fiber implantation animal studies conducted by Pott suggest that the morphology and size of a fiber regardless of fiber type are responsible for its carcinogenicity mineral Likewise the results of reported by Stanton et al fibers suggest implanted into the pleurae of rats that fibers less than 1.5 ...m in diameter and greater than 8 ...m in length pose the greatest risk in producing pleural sarcomas These studies suggest that the physical morphology size dimensions and to a lesser degree the chemical and surface characteristics of a fiber are the determining factors for inducing a biological effect The precise fiber dimensional characteristics required for these observed experimentally pathologic because of responses have been difficult to determine the difficulties encountered in producing inoculants containing fibers of specific dimensions Because of the adverse health effects observed in auto lack of a necessary clearly identifiable to minimize exposure effect concentration to brake dust repair workers and the for asbestos it is 2.1.2 Solvents Solvents observed to be used at various facilities during this study were trichloroethane commonly known as methyl chloroform and Greasofffi Trichloroethane is irritating to the eyes on contact Exposure to the vapors may result in adverse effects on the central nervous system Symptoms of overexposure include dizziness incoordination drowsiness and increased concentrations Unconsciousness reaction time () and death can occur from exposure to excessive GreasofffiNo. 19 contains less than 5 percent by weight sodium metasilicate and less than 5 percent by weight butoxy ethanol also known as ethylene glycol monobutyl ether or butyl cellosolve Sodium metasilicate a highly alkaline compound pH mucus membranes is hemolytic agent and 12.4 is severely irritating to the eyes skin and Butoxy ethanol can be absorbed by the skin and will irritate the eyes and upper respiratory tract This study was limited to the evaluation of the asbestos no determinations of airborne solvent potential for exposure to concentrations were made 2.2 EXPOSURE CRITERIA The two sources of occupational exposure criteria for asbestos considered in this study are 1 the NIOSH Recommended Exposure Limit REL and 2 the Department of Labor OSHA Permissible Exposure Limit PEL c. a 2.2.1 OSHA Permissible Exposure Limit On June 20 1986 OSHA 29 issued a revised PEL which reduced the allowable asbestos fiber exposure level 2.0 to 0.2 cc as an hour observed by phase contrast microscopy weighted average TWA exposure PCM from It also set an action level of 0.1 cc that triggers worker training medical monitoring and other requirements The new PEL does not set a ceiling or short exposure limit NIOSH recommends that worker exposure to asbestos be reduced to the lowest feasible limit due to the carcinogenic nature of this substance On September 14 for asbestos of 1 cc for a published 1988 OSHA a minute period short exposure limit 2.2.2 NIOSH Recommended Exposure Limit The NIOSH REL for asbestos is 0.1 fibers greater than 5 ...m in length per cubic centimeter cc microscopeystablished of using phase contrast and was based on the analytical limitations established - NIOSH reaffirmed its position on asbestos 1984 asbestos at the OSHA proposed rulemaking hearings ) summarized as follows for asbestos in June The carcinogenic potential of asbestos is no longer in doubt however there is some uncertainty about the toxicological and morphological properties which determine the carcinogenic potency of various fibers On 1 Ou FE we Ba Bartigee 2 Pra ge the basis of available information there is no scientific basis for differentiating between asbestos fiber types for regulatory purposes available to date provide no evidence for the existence of a threshold level Virtually all levels of asbestos exposure studied to date demonstrated an excess of asbestos disease Data Both asbestos and smoking are independently capable of increasing the risk of lung cancer mortality When exposure to both occurs the combined effect with respect to lung cancer appears to be multiplicative rather than additive From the evidence presented we may conclude that asbestos is a carcinogen capable of causing lung cancer and mesothelioma independent of smoking NIOSH has recommended that asbestos be controlled to the lowest detectable limit Any standard no matter how low the concentration will not ensure absolute protection for all workers from developing cancer as a result of their occupational exposure However lower exposures carry lower risk of disease Because the only widely available method NIOSH Method 7400 33 is able relative to achieve intralaboratory accuracy of 12.8 percent standard deviation at an exposure limit of 0.1 cc 100,000 min a 400 liter sample NIOSH and others have recommended an exposure limit REL of 0.1 cc for asbestos based with peak concentration not on hour exceeding 0w.e5 icgcht(ed) average concentrations The use of electron microscopy is recommended in the event of process or product modification in mixed fiber exposures or when there are other reasons for characterization of fiber type and morphology As stated above the occupational exposure criteria the NIOSH REL and the OSHA PEL are based on the PCM analytical method This method has inherent limitations based on the physics of the optical microscope and upon the ability of the microscopist to reliably discriminate fiber dimensions in a complex sample matrix The minimum diameter routinely observed is on the order of 0.5 ...m The NIOSH 7400 method stipulates that only fibers longer than 5 ...mbe counted with a either 1 A rules length or 1 to width ratio equal to or B rules The A and greater than B rules have other minor differences The A rules use the aspect ratio specified in the current OSHA PEL and NIOSH REL In the present study transmission electron microscopy TEM was used to counted and to differentiate determine fibers by the actual dimensions of length to width ratios all fibers A coarse analysis of our data by fiber differ by less than 8 percent aspect ratios indicates that fiber counts would between the use of 1 or 1 aspect ratios Another concern is that asbestos fibrillae as small as 0.02 ...m in diameter and less than 1 ...m in length are visible only with electron microscopy These fibrillae constitute a significant and variable proportion of the total fibers present in brake dust Thus PCM in counting only optically visible particles may not be a good indicator of the total fibers present Controversy over the health effect of small fibers and thus what sizes of fibers should be counted adds further ambiguity 8 nea IERe SRS 3 METHODOLOGY 3.1 OVERVIEW This study was conducted to identify evaluate and document technology used to control exposure to asbestos in the vehicle brake drum service industry During the first phase of this project through surveys of 12 work sites were performed to observe the work practices and control methods in use and to select systems which appeared to be effective for minimizing exposure to asbestos for detailed study Selection of sites was made based on the type of control technique being used at that site and the type and quantity of vehicles available for brake repair In the second phase detailed evaluations were performed at five of these sites A brake service operation using rudimentary control and one using no control were also sampled A site using compressed air and dry brushing could not be found therefore historical exposure data were used as a base line The evaluations included both extensive monitoring of airborne asbestos fibers and the documentation of work practices and were conducted at locations servicing different types of vehicles and employing a variety of work 1 practices The study focused on the state control devices and their acceptance among mechanics performing brake service 3.2 SITE SELECTION The through surveys were conducted at facilities employing a variety of control methods Sites were selected primarily from fleet garages so that a sufficient number of brake inspections could be observed and to control for variables such as vehicle type use and maintenance practice During the through surveys the effectiveness of the brake drum service control methods for preventing asbestos exposures were visually assessed These included Ammco Brake Assembly Washer Kleer Brake Washer Assembly Clayton Brake Cleaning Equipment Hako Minuteman Asbestos Brake Drum Vacuum System Nilfisk Asbesto System Lux Brake Assembly Cleaner a squirt bottle solvent wet method a squirt bottle method with vacuuming a steam jenny with vacuum a vacuum with wet washing and HEPA filtered vacuuming only 3.3 DEPTH SURVEYS A team of three to six researchers consisting of engineers industrial hygienists and engineering technicians conducted each depth survey The A specific control method evaluated was that used in the facility studied Other sizes or models of control devices produced by the same manufacturer and xt ye ? 0 ~ similar limited devices made by other companies may be more or resources precluded an evaluation of more than less effective however one model and size The methods used for controlling exposure were evaluated under the conditions of normal use i.e. the control hardware or work practices were not altered for this study For each control method six to eleven vehicles were evaluated 3.3.1 Air Sampling and Analysis The NIOSH Occupational Exposure Sampling Strategy Manual 34 suggests that the most reasonable sampling strategy for the most efficient use of sampling resources is to sample the employee presumed to have the highest exposure risk If there are a number of work operations as a result of different processes should be where there may be exposed employees selected for each operation Samples then a maximum risk employee employee taken for comparison with ceiling standards are best taken in a nonrandom fashion That is all available should be knowledge relating utilized to obtain to the area individual and process being sampled samples during periods of maximum concentrations of the substance Two personal air samples for asbestos were collected side in the breathing zone of each worker for the duration of a single brake job or for 2 hours whichever was longer Samples were collected on 25 mm diameter 0.8 ...mpore size cellulose ester membrane filters at a flow rate of 2.5 to 3.0 Lpm using a personal sampling pump The minimum volume collected 300 liters allowed a limit of detection LOD of approximately 0.004 cc by Phase Contrast Microscopy PCM analysis The LOD for one set of personal samples collected for 1.2 hours was 0.008 cc Area air samples for asbestos also were collected on 25 mm diameter 0.8 um pore size cellulose ester filters Two area samples per vehicle source samples were collected one near the fender and the other under the axle at a flow rate of approximately 7.0 Lpm using rotary vane vacuum pumps for the duration of a brake job or 2 hours whichever was longer The source samples were used to determine if fibers escaped into the working environment during the repair activities The minimum volume collected 840 liters allowed a LOD of 0.002 cc by PCM Two additional area samples background samples were collected in the garage at least 10 feet from brake repair activities at flow rates of 7.0 to 10 Lpm for each hour sample period These background samples were used to determine the effects of general shop cleanliness and overall effectiveness of the dust control procedures The minimum volume collected 1,000 liters allowed a LOD of 0.002 cc by PCM Samples were also collected doors ambient concentrations to determine environmental concentrations of asbestos These ambient samples were collected at a flow 8 hours rate of approximately 3.0 Lpm using personal sampling pumps for up to The minimum volume collected 800 liters allowed a LOD of 0.002 cc by PCM 10 mated y All filter air samples were analyzed by PCM using NIOSH Method 7400. In addition to analyzed by of PCM analysis approximately 80 percent of Transmission Electron Microscopy TEM . these 35 To samples were facilitate direct analysis by PCM and TEM on the same samples the sample preparation described by Burdett and Rood transfer method of ) was used modified by the omission of the filter etching TEM analysis was performed to identify asbestos fibers and determine concentrations for fibers too small to be detected by optical microscopy analysis In our study almost all of the fibers in the brake dust were too small to be measured optically For PCM analysis all fibers with a 1 or greater length to width aspect ratio were counted using Method 7400 A small number of samples were analyzed by PCM using Method 7400 counting rules because the routine laboratory procedure for Method 7400 was changed to A counting rules before these samples were analyzed While the OSHA PEL and the NIOSH REL are expressed in terms of fibers having a 1 or greater aspect ratio the difference in counting rules has little practical significance in the case of brake dust Few fibers were identified in this study with aspect ratios between 1 and 1 Data on fiber aspect ratios 7402. is presented TEM analysis was performed using NIOSH Method ( Fibers in Section were 5. identified by morphology selected area electron diffraction SAED and dispersive ray analysis EDXA Fibers were classified in one of four mbiguous mbiguous categories chrysotile amphibole fibers patterns were observed for all , and Fibers no identification SAED were also identified by asbestos structure fibers bundles clusters and matrices and sized by length and width All fibers with a 1 or greater aspect ratio were analysis using TEM The was performed using a magnification of 17,600X area of 0.000081 cm and counting either a minimum of 10 grid openings counted grid or 100 fibers whichever came first The limit of resolution was approximately 0.06 ...m thus the minimum fiber length that could be measured was 3 times the limit of resolution or about 0.2 ...m One or two field blanks were prepared for each vehicle sampled and submitted for PCM results on both PCM and TEM were obtained by a contract and TEM analysis from DataChem The Cincinnati Ohio The analyses were performed in NIOSH laboratories with NIOSH instrumentation and oversight Analyses were performed according to contract which the specifications for both calibration contractor to follow all procedures and quality control in NIOSH methods 7400 required and 7402 for PCM and TEM respectively Specific quality control measures include submission and laboratory analysis of field blanks Analysis of blind and double quality control samples and checking of asbestos microscopic analysis by a NIOSH analyst who participates in the Proficiency Analytical Testing PAT program In conducting their oversight functions NIOSH laboratory managers adhere to Manual the Engineering Quality Control Division of Physical Sciences and 38 * Six samples etched and recounted by TEM showed no change in fiber count 11 A bulk brake dust sample from each vehicle and a settled dust sample from each repair facility were collected and analyzed for asbestos by TEM The percentage of asbestos in the bulk samples was qualitatively established by estimating the ratio of the number of asbestos fibers to dust particles Fibers were identified as asbestos using morphology SAED analysis and EDX analysis the length and diameter of asbestos and other fibers were measured and the percentage of asbestos of the total fibers present was quantitated 3.3.2 Ventilation Kurz Model No. 480 and TSI Model No. 1630 air velocity meters were used to measure air velocities to determine flow rates and directions in the garages Smoke tubes were used to assist in the observation of general airflow patterns Design airflow rates were obtained from the companies at several facilities Air temperature humidity and wind conditions were determined using an aspirated psychrometer and velocity meters 3.3.3 Ergonomic Evaluation of Brake Maintenance and Repair For several of the control methods evaluated in this study an ergonomic evaluation was conducted on workers performing brake maintenance and repair to determine if specific work practices contributed to the worker's exposure to asbestos Each worker was videotaped during routine brake inspection and brake replacement tasks Work cycle times and work analyses were performed from videotapes in the laboratory Cycle times were taken with the video tapes running at normal speed work analyses were conducted at both normal speed and by action techniques Work analysis included breaking the job into general tasks which could be correlated with relative airborne dust concentrations during brake inspection and replacement Work tasks which could cause personal exposure to brake dust were identified 3.3.4 Time Sampling The entire brake maintenance operation was recorded on Aerosol Monitor HAM from PPM Inc. and an Apple II videotape A computer were held used to measure and record the dust concentrations during most of the brake studies The electro system to the relative respirable of the HAM generates dust concentration a millivolt signal proportional Before each brake job the HAM was calibrated and zeroed and the clocks in the computer and video camera were synchronized Either DuPont 4000 or MSA Model G pumps were connected by tubing to the HAM which in turn was connected by a foot electrical lead to the computer programmed to receive the data The brake mechanic wore the HAM in his breathing zone while performing the brake maintenance Data was recorded at second intervals The computer converted the output signal from the HAM to relative dust concentrations and stored the data on a floppy disk Using a spread sheet program Lotus 1-2-3 a time plot of the relative dust concentrations was made By identifying the various activities during brake maintenance wheel removal brake drum removal cleaning brake parts removal brake parts and brake drum reinstallation and wheel remounting 12 Re: cae f al Ee dust concentrations during each of these activities can be compared average The peaks from the plot delineate work activities activities which produce elevated dust between the concentrations Also the average dust levels levels can be compared various control methods used The HAM is not not specific for asbestos however of the brake dust and therefore the HAM can asbestos fibers are a component be a useful real monitor for the control control of asbestos dust 13 4 CONTROL METHODS AND FACILITY SITES SURVEYED In this study five methods for controlling exposure to asbestos during brake repair were evaluated These included two enclosure devices with ventilation provided by a HEPA equipped vacuum a HEPA equipped vacuum cleaner with no enclosure a wet recycle system which recirculated the cleaning solution and an aerosol spray to wet and flush away the dust In addition one brake repair that used no control measures and another that used minimal controls were studied Each control method was evaluated at a different facility This introduced many uncontrolled variables such as building layout traffic pattern and ventilation system Also the types of vehicles and wheel sizes were not identical among the control methods tested The description of the control device is followed by information about the facility in which it was observed and the vehicles serviced This information is summarized in Tables 4-1 and 4-2 4.1 VACUUM ENCLOSURE * 4.1.1 Control Description This engineering control consists of a glove box for completely enclosing the brake assembly for brake drums up to 20 inches in diameter after the wheel has been removed Figure 4-1 shows the glove box enclosure and the vacuum filter assembly unit The front of the glove box enclosure is constructed of clear Lexan plastic and the back is comprised of flexible overlapping neoprene fabric strips These allow the brake assembly to be easily inserted into the enclosure and also provide an essentially tight seal around the axle Two long gloves are sealed into the front face of the enclosure and extend inwardly These flexible gloves permit the mechanic to insert his hands and arms up to and sometimes past the elbows to operate a conventional compressed air gun a vacuum line with brush attachment a hammer and mallet a separate brush and other tools within the enclosure to clean the linings pads and other base and can be elements of the brake system The enclosure is mounted to a rolled to its destination Four corner frame posts support the enclosure and allow easy adjustment to a convenient level for servicing a vehicle on a lift rack * Line BCE 2500 Clayton Associates Inc. Farmingdale NJ 14 aay PTOD- zeom dusy aopuy/ (A epts o) PpITtWS8-04 *{o9OL~-S9 S9-0S TableTable PTH Gi-S9 zno SITUBYION(aquin Z 9 T1 OT Ventilation ) yqUuOn SoyeigpadstAras aed O-S@ ( L GZ SE-OE pue Dilution Enclosure 10,0 TBoUeYON Mechanil TBanjeNn 197 TeanjeNn Mechanicl Enclosure AVINS uoTtyn{ uot uot uot Dilution atndt 1t0,1d0 yntd ta Mechanical Vacu m Vacum9T4deL APET (ae3h) RecyleBrush Ss Ol61 L6T ,0S6T Natural Mechanical 6L6T Mechanicl Dilution ('33 BoUueszTAayeid bs) 00z eT 10,00 Oleh BAA Be4V 1970's Mechanical Mechanical s Dilution Dilution (aequnskeq T Tl tt eT OT- < 410M ) y q apToAveusynig sanozpug vansojug ATuQ keadsg yo1zUSg wnse wnoeA wnoen 38M [OSo19y 15 Table 4-2 Vehicle Description Control Type Number Model Year Brake Drum Diameter inches) Vehicle Serviced Transmission Vacuum Enclosure A APVT 252 APVT 252 APVT 252 / A 1979 1977-85 1983 1977 9-10 10 11 17 Vacuum Enclosure BA A<V 182 A<V 182 A<V 182 1979 1974-83 1977-84 11 9-11 11-14 Vacuum Only -- 22 1977-82 9-10 AV 22 1977-79 11-14 Wet Recycle J 10 1973-81 9-11 Aerosol Spray A 1 P 2 V 2 TT 1 1980 1983 1982-83 1981 10 9-11 11-12 16.5 2 Rear 2 Rear 2 Rear 2 Front Auto Auto Auto Manual 2 Rear 4 Front 2 Rear Auto Auto Auto 2 Rear 2 Rear Manual Auto 4 Front Auto Rear Rear Rear Rear Auto Auto Auto Auto * A = Automobile J = Jeep P = Pickup Truck V = Van 1 to 2 tons 1.5 tons 1/2 and 3/4 3 to 5 tons curb weight curb weight ton size curb weight T == Truck TT = Truck with Over 10 tons empty weight tandem rear wheels 13 tons empty weight 16 OVERLAPING WONIA OVERLAPING FdNSO asi GGLLOOVVEESS GLOVES dia-e 4JOVLS ATquase J9}TZ pue FILTER VAOTS Y sanoTug "T-y 94an8ta4 l7 The enclosure by a flexible is connected to a vacuum pump hose The first filter stage with is a a stage filter assembly bag similar to a conventional home vacuum cleaner bag The second stage a inch square prefilter is similar to home hot air furnace filters The third stage is a HEPA filter removing rated as diameter 99.999 percent of particles greater All filters are commercial items The than 0.12 ...m in filter life is dependent on the amount of use and the total collection Brake servicing using this vacuum enclosure is accomplished in the following manner After the vehicle is raised and the wheel is removed the vacuum enclosure unit is placed within the rolled in front enclosure The of the wheel vacuum pump is Tools and auxiliary items are started and the unit is moved forward so the enclosure completely envelops the brake assembly the rear four flap tightly wraps around the axle The gloves and either a hammer or mallet then removed drum is and set loosened using the aside face up within the enclosure The loose dust is vacuumed from the inside of the wheel drum the surface of the brake shoes and assembly Dust adhering to the brake assembly is brushed and blown off with compressed air The dust cloud generated within the enclosure is dissipated as the vacuum pump draws clean air through an inlet valve on the side of the enclosure and exhausts the contaminated air through the dust filters The drum shoes and parts of the assembly are again vacuumed as well as the inside surfaces of the enclosure This unit procedure takes is removed from up to 5 minutes After cleaning the vacuum the brake assembly and the brake maintenance enclosure is completed An important operation not observed during the survey is the removal and replacement of the filters in the vacuum units Normally the first stage bag filter is replaced when the bag is about half full at this point the pressure indicated by the vacuum gauge on the unit is about 4 inches of water For a production rate of 10 brake inspections per week the second stage prefilter is replaced in about 3 to 12 months and the third stage HEPA filter is replaced in about 3 to 5 years The HEPA filter requires careful installation to prevent bypass leakage The manufacturer of this unit has introduced an exchange service whereby a dirty assembly returned to the manufacturer's plant will be immediately replaced with a new HEPA assembly The facility has employed this control device to reduce occupational exposure during brake inspection repair and brake lining replacement of all motor vehicles since early 1986. The mechanics thought the vacuum enclosure did a good job of containing and collecting brake dust when employed on cars and light pickup trucks They thought that the unit was bulkier than necessary for light vehicles The brake assemblies of large trucks and specialty units equipped with double wheel assemblies are different and much heavier than for light vehicles however and the workers did not consider this particular model to be as effective with the heavier vehicles 4.1.2 Facility Description This state government 180 large trucks 250 vehicle maintenance facility completed in pickup trucks 90 passenger cars 25 vans 1970 services 25 loaders 18 and other specialized road maintenance units Figure 4-2 Repair work includes brake work general maintenance and engine overhauls and requires a substantial amount of specialized auxiliary equipment The light vehicle area is separated from the heavy equipment repair section by a double row of lighted work benches and mechanic workstations Overhead hoists are mounted in both garage areas for raising and moving the vehicles Operations are conducted on a shift basis from 7:30 a.m. to 4:00 p.m. by 11 veteran mechanics 2 body men and 3 welders Most of the appr mately 300 to 500 annual brake jobs are performed by 5 to 6 mechanics The garage is situated so that ventilation through open doors prevailing wind currents provide natural during the warm months of the year Fumes from vehicle engine testing are removed by means of flexible hoses fitted over exhaust system pipes The hoses are connected to exhaust fans which discharge outside the building roof The vehicle repair areas are exhausted by five 3,100 cfm roof fans Four exhaust grilles mounted approximately 18 inches above floor level are connected to four mounted fans of about 3,000 cfm capacity each A 12,000 cfm direct make air heating unit is interlocked to provide additional heat when any of the fans are operating Brake maintenance on nine vehicles -- two automobiles one passenger van five half pickup trucks and one large dump salt truck -- was evaluated using this vacuum enclosure control The vehicles ranged in model year from 1977 to 1985 and the vehicle mileage ranged from 16,000 to 106,000 4.2 VACUUM ENCLOSURE B 4.2.1 Control Description This control device consists of a inch diameter steel cylinder 16 inches long equipped with a single rubber glove and a connect fitting for an air hose Figure 4-3 A compressed air cleaning nozzle is located inside the cylinder One end of the cylinder is partially closed by an type rubber flap connected by a cloth covered elastic band so that a inch diameter opening remains A plastic window is provided in the other end to observe the cleaning operation The cylinder is mounted on a rolling stand The height is adjustable and secured by a thumbscrew The cylinder is connected to a HEPA equipped vacuum cleaner With the enclosure on a vehicle wheel and the vacuum on this unit was observed to produce a face velocity of 150 to 200 fpm approximately 30 to 40 cfm at the seal opening around the axle of the vehicle The vacuum cleaner may be easily disconnected from the cylinder enclosure to function independently as a cleaning device The vacuum cleaner has a set of four filters consisting of a first stage filter and a 6 mil polyethylene liner bag a microfilter a main filter filter rated at 99.97 percent removal of 0.3 ...m diameter dust a HEPA ) All but the main filter are replaced about twice a year The main filter can be * Nilfisk Asbesto 500 System Nilfisk of America Inc. Malvern PA 19 8530 - - vauy y Cleanig VEHICLES wos HEAVY BsanoTIUa 96 vav -ALNG sos /SIl YIM AAV vav LALA ase3 Genral SAH. -| Area jo ynoAey Aazuedng Gous | 2- Shop Body Body FOR FOR pAepso dous an3t4 dous Apog COus Suipjem urog dous Sol 20 Sr WANITA scp | VACUM poVAS QNISdO MON: GD IANSSCNT dAs-STat MdvOLNYa IAL 21 -wa3sk gq VACUM HOSE e-y ean3ta lee eri Se ne purged and are placed should last 20 years At this facility the contaminated in a gallon metal container which is filled to capacity concrete and then disposed of as ordinary waste filters with The following general brake cleaning procedure is vehicle is driven onto the lift and raised 3 to 4 used at this facility The feet The lug bolts are unscrewed and the wheel and brake drum are removed The vacuum enclosure is installed over the backing plate of the wheel and dust on the brake components is blown off with compressed air After the enclosure is removed the inside surfaces are vacuum cleaned The brake drum is also vacuumed A supervisor inspects the brake components if the brakes need replacing the new shoes or components are installed otherwise the drum and wheel are reassembled If previous maintenance on a vehicle occurred within 1,000 to 1,500 miles two wheels are pulled and the brakes inspected If the vehicle has been driven more than 1,500 miles since the last maintenance all four wheels are inspected This facility began replacement of asbestos brake linings with nonasbestos type materials in July 1986 several months before our survey Nine of the eleven vehicles evaluated had asbestos type brake shoes 4.2.2 Facility Description This postal maintenance facility industrial park in a building 158 constructed in 1977 is located in feet long and 81 feet wide Figure an 4-4 The repair area body shop and paint shop occupy a high bay area of approximately 10,000 square feet The main shop area contains twelve bays floor vents and ceiling hoses rated at 300 cfm each are used to exhaust engine fumes through a single centrifugal fan suspended from the roof This system operated on an needed basis to control vehicle exhaust was in use during this survey Two centrifugal fans suspended from the ceiling have inlets located near the floor exhaust air at a rate of 4,960 cfm each through the shop roof and are operated on an needed basis They provide about 3 air changes per hour when operating however they were not observed to be used during this survey About 6,600 cfm of heated make air is provided through a central overhead plenum with six outlets The facility is open from 6:00 a.m. to overlapping hour shifts all perform inspections are conducted 6:00 p.m. Eleven mechanics brake service About 28 to each week work 36 brake Evaluations were eight Jeeps one inch diameter made while brake service using enclosure B was performed on automobile and two vans These vehicles had 9- 11- and brake drums The model year of the vehicles ranged from 1974 to 1984 and the mileage ranged from 16,000 to 85,000 miles 22 RACK | | | j= dOHS | \ a\0DS ON ACO owe INIWd dOHS Td sOvaLS BODY gq | ENTRANCE ENTRANCE 81 / / SAVE WORK MaVa y BAYS HSVA / WAOM SNWaL wos danso[Ue | C18 GULaL s YIM * Pp PAINT BAYS LGM valjnaf PAINT OPEN IV | SHOP | ad . 7-7 WAY BAT FALYSINGY TIRE STORAGE ADMINSTRAIVE ADMINISTRATIVE 3dU | RM ROOM \ | | || Layout | 4 4 B.B. __s | | ! || i 23 os, pat op ot lS se 4.3 VACUUM ONLY wes 4.3.1 Control Description This HEPA filter equipped vacuum has been in use since about 1978. It consists of a dust removal hose connected to a stage HEPA filtered vacuum assembly Figure 4-5 Coarse particles are separated by centrifugal action in the bottom area Finer particles are collected by a main filter followed by a used micro filter Finally a HEPA filter is 99.97 percent removal of 0.3 ...m dust ) to remove the very fine dust The vacuum unit is used during all brake inspection repair and brake lining replacement work In the brake cleaning procedure vacuuming is done after the hubcap wheel and drum are removed Loose dust is vacuumed from inside the drum and from around the brake assembly After disassembly small parts springs screws etc. are generally vacuumed No blowing with compressed air or wet methods are used No special attachments are used with the vacuum hose Air is drawn into the 1.25 inch diameter nozzle at about 95 feet per second 50 cfm After cleaning the brake is inspected and then either reinstalled or repaired An infrequent operation not observed during this depth plant survey is the removal and replacement of the filters from the vacuum units The filters are changed at about the same frequency as described for vacuum enclosure B units 4.3.2 Facility Description This is one of several fleet garages operated by a privately owned utility Eighty assorted specialized vehicles are based here Routine maintenance such as 10,000 inspections brake work on light vehicles and tune are performed but not major vehicle overhauls About seven vehicle brake inspections and three brake replacements front and back are performed each month The two mechanics employed at this garage are assigned to the second shift The building is 182 feet long 123 feet wide and 15 feet high Figure 4-6 A single hydraulic lift is employed to raise light duty vehicles to the desired height for brake inspection and replacement Ventilation is provided by a 3,800 cfm exhaust fan on the washroom wall and another 5,000 cfm wall fan at the rear of the garage This provides about two air changes per hour There is no provision for make air except for infiltration through doors and windows This may result in negative pressure in the building especially when the doors are closed in cold weather The garage is steam heated and is not conditioned A carbon monoxide monitoring system is set to operate an auxiliary ventilation fan if the carbon monoxide level reaches 35 to 39 ppm * Nilfisk Vacuum Cleaner Model 81 Nilfisk of America Malvern PA 24 Li qivd La ONIDOVa ON Bo SoA\ WNW.\ v S -Wanova -3aT} WdaH uziM uNseA ANOYA "ST" ainat NGL 14 with 25 <2l | AV@ 37 NF BRAKE JONVSLIW| IDRSA FOVNLS NN / AVMITAC WASHOFICE 'OFICE/ MA y WASH at rel Woe uNoeA YIM Srl eB8azes Jo ynokey / rsoM |)| | i 30140 aes LE 9-y LL ! 4| _ GAN3Tgy en ~_ | 7| oe | 26 During the November 24 and December 9 1986 surveys the main doors of the garage were generally open which provided some air circulation within the garage However during the surveys conducted on December 11 and 16 1986 and January 12 and February 5 1987 the doors were closed except for vehicle entry and exit Brake servicing using the vacuum only control was evaluated on -- two automobiles and five utility vans -- all with rear drum seven vehicles brakes The model years ranged from 1977 to 1982 and the mileage ranged from 52,000 to 92,000 miles 4.4 WET RECYCLE 4.4.1 Control Description Asbestos exposure is controlled by a brake washer assembly Figure 4-7 An aqueous solution containing an organic solvent is pumped through a nylon filter directed through a flexible tube and out between the bristles of a brush It provides for a gentle flooding of the brake assembly area to wash down dust and perform the necessary cleaning The solution captured in a catch pan is returned to and recirculated from a reservoir This system provides a gentle flow of solvent to wet and clean the back plate and brake components without disbursing brake dust into the air A movable workshelf basin can be positioned to avoid splashes and spills The low center of gravity of the unit resists tipping and potential spilling of the cleaning solution which may contain asbestos fibers A removable cover for the reservoir prevents evaporation of the liquid and serves as a work tray when the cover is removed for work on large vehicles The portable washer can be used for brake maintenance of both automobiles and trucks The following sequence is used for brake shoe servicing The reservoir is filled with 1 gallon of brake cleaner concentrate and 5 gallons of water brush is placed in the catch basin to prevent accidental spillage and loss The of solution With the vehicle on a lift the lug nuts wheel and brake drum are removed and the washer is placed so that the catch basin is directly under the brake assembly If the vehicle is raised by a front lift or jack the catch basin and the hinged reservoir cover can be removed and cleaning can be performed over the expanded metal mesh shelf in the reservoir tank When the washer is properly positioned the pump is started and the fluid flow is controlled by a valve at the hose connection The brush is used to assist in the removal of dust asbestos fibers oil and grease from the brake drum and brake assembly Small parts are cleaned and stored in the catch basin or on the screen in the main tank After cleaning the brake is inspected and then either reinstalled or repaired * Kleer Model LW Rollaboutfi Kleer Company Eden Prairie MN 27 sil .7~ e HOSE~ BRUSHLo. ~ 74 mLN SD os oe\ Td \ el Bh ()\\ 4 sweaqsk oTADea/synq 4ATSH SOK OCR RO Nve Oe uoO eM MM 7 > =~ ~, } /- a3Na4 an3ta A \ 'PUMP \ WAG S4Vvad 28 One gallon of GreasofffiNo. 19 mixed with 5 clean 40 to 50 wheels before it is disposed gallons of water of in accordance is used to with local state and federal requirements The barrier filter should be washed at that time At this because facility it had to the unit be moved was somewhat awkward to shift from over electrical cords or air lines wheel to wheel on the floor However asbestos the workers were confident in the brake dust that it that the unit did allowed the brake reduce their exposure to components to be cleaned well and that it was easy to use 4.4.2 Facility Description This control method was evaluated at a postal maintenance garage which services 575 vehicles The foot garage building Figure 4-8 was opened in 1979-80 It includes a 64 by foot working area with a foot ceiling There are 14 bays 12 are equipped with hydraulic lifts The garage staff consists of ten mechanics four garagemen one body man and two supervisors Each vehicle is completely inspected twice a year approximately 25 brake jobs are performed each month Ventilation of the garage is minimal floor hose and pipe systems to remove auto exhaust fumes are used only when a vehicle engine is operating Several mounted fans on each side of the garage are operated in the summer to remove hot air from under the roof area In the cooler months these fans are not used and the inlet dampers are closed There is no provision for fresh heated air During mild weather ventilation is provided by the open bay doors The building is heated to about 60 to 65 F at the working level during cold weather During most of the survey one or more doors were open The evaluation of brake maintenance using the wet recycle method was performed on 10 Jeep vehicles manufactured in 1973 through 1986 All four wheels are equipped with drum brakes drum sizes ranged from 9 to 11 inches 4.5 AEROSOL SPRAY 4.5.1 Control Description This control method consists of a solvent methyl chloroform spray to control potential vehicles asbestos exposures during brake maintenance on Typically the operator dispenses the solvent all types of from a refillable held sprayer Figure 4-9 1 quart of solvent the solvent drum using a mounted pump The sprayer is filled with approximately is transferred to the sprayer from a gallon Shop air at approximately 200 psig is used to pressurize the sprayer In the brake cleaning procedure the hubcap wheel and drum are removed A catch pan is placed under the brake assembly and the exposed surfaces are * Balkamp 770-551 Model A Sprayer Balkamp Central Div Indianapolis IN 29 nmcenn cq e tccniren sr ret a 8 Apog GOUs pUlod dous *aToOADsyniq N GARAGE MAINTENANCE D 2 cshog Yayv JOM GENRAL 4OmM VZets SHOP GIL YIM ayOIS AREA ON 79) jo Bays | pe 1d ynokey 13 *g-y NIVW oan3tga AJA Wwoy WO M '458)3 "SUD 10g HDO1LS 2130) 30 J)VGNVH Lar NOZLE e WYGNLS Nid a div a e/t dV 4A i WA NS sazon HANDLE GINSIT [os1ey LIQUID -6- eS oun3Tta 31 thoroughly wetted The sprayer is held about 18 inches from the brake drum and the other components so that brake dust is not blown off to become airborne before it 12 inches is wetted Washing is then performed by moving the sprayer to about from the parts The contaminated solvent is collected in the catch pan It is not recycled but is emptied into a waste drum to be disposed of as toxic waste Some mechanics wipe the parts and drum with dry rags After cleaning the brake is inspected and then either reinstalled or repaired Occasionally the solvent is applied directly to the brake drum and brake i components with a parts brush manual wet residue The catch pan containing about brush method to remove 2 inches of solvent is the brake placed on the floor near the vehicle The brake drum is removed placed in the catch pan cleaned with a solvent laden brush and then wiped with a dry rag The pan is 4 then placed under the wheel to catch the excess contaminated solvent as the other brake system components are also cleaned with the brush The clean components are wiped with a dry rag and the contaminated solvent is emptied into a waste drum and disposed of as toxic waste The job unit is small lightweight and appears easy to use in cleaning the brake components and has very little It seems to contaminated do a good solution to dispose of One disadvantage occurs when it is first activated to clean a wheel If the nozzle is too close to the brake surfaces within about 12 inches pressure from the nozzle causes brake dust to become airborne 4.5.2 Facility Description This private utility has 10 garages to service about 1,400 vehicles The buildings range in size from a single workstation to a bay garage Maintenance is performed on cars pickup trucks vans specialty vehicles slightly larger than a pickup truck medium size trucks and large specialized line trucks The annual maintenance of these vehicles includes brake inspection Each month all the wheels on approximately 30 to 35 vehicles pulled for brake inspection and 65 to 70 percent of these undergo brake replacement or repair A total of 89 mechanics at these 10 installations are perform brake maintenance In our study brake service was evaluated at four of these garages The first located in a congested industrial area is part of a larger building Maintenance is performed on 250 vehicles assigned to this location by 10 mechanics in a square area containing 10 work bays Outside air is drawn exhausted by mounted in through fired heaters building air is fans Because of the mild weather doors were open and the fans were not in use during the study The second garage is located beneath a high office building in the downtown area Maintenance services are performed on 225 vehicles mainly automobiles by 5 mechanics in a 1,500 square area containing 3 work bays Fresh air entering through a wall duct exhausts naturally into an alley next to the garage 32 The third garage located in a rural area is a 3,300 square structure Although not in use at the time of the study two mounted exhaust fans are present Maintenance is performed on 115 vehicles by 7 mechanics in 4 work bays The fourth garage is part of a large 45,400 square multipurpose facility located in a congested industrial area Maintenance is performed on 150 vehicles by 8 mechanics in a 5,500 square area containing 3 work bays The two mounted exhaust fans were not operated during the study however open doors leading to the rest of the building provided ventilation The study of the aerosol spray method was performed during brake servicing to six vehicles at these four garages in one case the mechanic serviced two vehicles truck with Only rear five sets of samples wheels and inch were obtained for drums was studied this method One large in addition to five automobiles with smaller drums 4.6 Rudimentary Controls and No Controls Airborne asbestos concentrations were measured during brake servicing of the rear brakes on a size van by a yourself mechanic A spray can solvent was used to wet the brake drum surfaces and dissolve accumulated grease and dirt and a garden hose to flush the surfaces with water The work was performed in a driveway doors Asbestos concentrations were also measured during servicing of the rear brakes on a utility vehicle No dust controls were used the brake drums were banged on the floor to remove the dust The cleaning of the brake drum was of very short duration and the brake assembly was not cleaned The work was performed in a small service station garage and the doors were open during the sampling period 33 5. RESULTS 5.1 ASBESTOS CONCENTRATIONS AS DETERMINED BY PCM The average and range of personal sample concentrations for airborne asbestos fibers determined by PCM are presented in Table 5-1 for the five different control methods used during brake service These results include exposures encountered while workers serviced brakes of small and medium size vehicles and two large vehicles Area samples PCM collected near the fender and over the axle of all vehicles were less than 0.002 cc see Table 5-2 Of 83 personal samples collected on brake mechanics in the present study the highest concentration determined by PCM was 0.016 cc This is about four times the LOD for the personal samples 0.004 cc Personal sample concentrations represent only those exposures which occurred while brakes usually 2 to 3 hours per shift and not the weighted servicing average exposure for the entire work shift Usually only one brake repair was ney. performed per day thus the would be lower Arithmetic weighted average exposure of the mean fiber concentrations while using mechanic either of the vacuum enclosures or the wet recycle with recirculating solution were /0.004cc methods were Exposures while using the vacuum only and the aerosol spray /0.016cc For vacuum enclosure A all 18 personal sample concentrations as determined by PCM were less than the LOD Figure 5-1 shows the percentage of personal samples that were below the LOD of 0.004 cc for each of the five control methods For vacuum enclosure B 21 of 22 personal sample concentrations were below the LOD The exposure for a yourself mechanic using a spray can solvent and garden hose during a brake replacement averaged 0.007 cc using Method 7400 A rules Table 5-1 A brake service operation was sampled in which no dust controls were used and the brake drums were banged on the floor to remove dust fiber concentrations PCM for both personal samples were below the LOD of 0.008 cc Method 7400 A rules The permissible exposure limit PEL of 0.2 cc OSHA action level 0.1 OSHA OSHA OSHA cc hour time average and the NIOSH recommended exposure weighted limit REL of 0.1 weighted cc are based on the PCM analysis of asbestos using A counting rules 1 aspect ratio B counting rules 5 aspect ratio were used in this study except where noted and the results cannot be directly compared to the OSHA PEL or NIOSH REL However TEM analysis of the filter air samples showed that 82 to 95 percent of all fibers counted using a 1 aspect ratio would also have been counted if a 5 aspect ratio was used This 34 Control Control Method Method g0O aZzuey(29/3) Control 0> - - - ~- g00> - (AOd) Vacum enclosure enclosure enclosure A pouzeH ues FoUATV TO17U0D OT (29/3) Uncotroled UnWcoattroelerd UncotroledhUoncotsroleed and solvent solvent Aq su T-S oTzeaqusD jo 9T98L sot saqunN dues 8 vA Z SI ce el OYA Jaqta etTdues yY Samples Arithmeic aTvA0/synaq peTosqu.n Vacum enclosure ansoTu sanoTIUus 7 keads < < spray wnser 10 3 eM [os7ey < by Control 70 Control 20 Method Method ( PCM Arithmetic OlXV WTQoOUYTAy f T0 0O Z0 0> z0 0> 20 0> TO0O 0> jo (HOd) a9qUN 0.04 < 6 8 S < suotzeaqs@-S U0) 700 700 9TQPL Table asueyd(9/3) Z0O> Z0O> 0OZ00>0O> Fiber ugaQ Range aepuagDTZOWYIAy Number of Z0 0> Arithmetic Arithmetic Arithmetic Arithme ic jo sot 7ASqUN dues < 6 L S 0.002 yq < poyuzeH ansoyTue @ansoT.US AyTuo Keads T01}U0D wnoe, WNdeA wnoeaA eM [osley 35 (FIBERS/C) (FIBERS/C) SAMPLES ING PERSONAL 10 ING CONETRAION F/C ING 0.2 OF SPRAY STD. CENT OSHA OSHA OSHA analysis indicates that there would be little difference in fiber concentrations using either fiber aspect ratio criteria Personal samples analyzed by PCM indicated that the TWA exposures of the mechanics would be all below the NIOSH REL for asbestos of 0.1 cc and the OSHA PEL of 0.2 cc even if they performed brake servicing for the entire work shift In most cases the mechanics performed only one or two brake jobs per day so that their TWA exposure would generally be less than the levels shown in Table 5-1 5.2 ASBESTOS CONCENTRATIONS AS DETERMINED BY TEM TEM results are not directly comparable to the PCM data because 1 TEM counts fibers include greater all fibers regardless of length whereas PCM includes than 5 ...m in length 2 TEM counts include fibers too only thin to be seen using PCM and 3 TEM data include only fibers identified as asbestos that only whereas 8 of 57 PCM data personal include samples any fiber contained type The TEM analyses asbestos fibers 5 ...mor showed longer 5.2.1 Personal Sampling Results Asbestos concentrations obtained in the breathing zone of the mechanics and analyzed using TEM are summarized in Table 5-3 for each of the 5 control methods evaluated These results exclude exposures encountered while workers serviced brakes to the two large vehicles All fibers identified as chrysotile or amphibole asbestos with an aspect ratio of 1 or greater were counted fibers 0.2...m in length Amphibole asbestos was found on only 7 of 219 filter air samples analyzed one or two amphibole fibers per filter Arithmetic mean asbestos exposures ranged from less than 0.013 cc the wet recycle with recirculating solution to 0.052 cc for while using the aerosol spray method Personal sample concentrations were found to be at the low end of this range for vacuum enclosure A and the vacuum only system and at the high end for the vacuum enclosure B. The arithmetic mean exposures for the aerosol spray and enclosure B were significantly higher than that for the wet brush recycle 0.05 The arithmetic mean exposures for the vacuum enclosure A and for the vacuum only system were not significantly different than that for the other three methods Geometric mean asbestos exposures ranged from less than 0.013 to 0.045 cc for the five control methods evaluated The geometric mean exposures for the mechanics using the spray can and garden hose and using no control were 0.039 and 0.048 cc respectively The arithmetic and geometric mean exposures are illustrated in Figure 5-2 5.2.2 Source Sampling Results Asbestos concentrations near the vehicle fender and axle excluding large trucks are presented in Table 5-4 Arithmetic mean asbestos the two concentrations near the fender ranged from 0.006 cc to 0.115 cc arithmetic 37 UBsR_ Method (9/3) PersonalPersonal Personal Personal Sample Sample Asbestos 8z70O 79TO 0Z00 9100 <20'0 Control Method TEM TEM - ~ - - ~ ( TEM 700> 0'O> 2z00 (RAL) $900 6 <TO16 10O> 6400 600 Vacum enclosure onlyenclosure - - 13 - - 600 Aerosl OT0O ETOO> 10 <100> <T00200 Water uot Limts <-S Limts detciondetectiondetcion vary vary with with eTQeL sample Note ueQ SO aTdules Jsaqsy (273) 1z0'070'0zOZz0'0 <T0'> Source Source Source Asbestos OTRzWUAYControl YIM jo ATBA T Teuosied 29qun sedues UOT 9 Mean Mean Samples Mean Mean Mean 0.0 4 V 0.010 0.15 0.005 sanoTus 0.8 recyle 0.15 Aeids psukoey 0.63 0.10 PeTos3UOCn solvent unoe, 0.36 0.36 0.036 yosiey 19eM :30N @TXV ( uBeR 900 Z10O0~- - - - - 0.002 0.013 - 0.045 z20080'090Q> 0.028 0.028 0.19 0.013 SUOTReI3zsND 0.024 0.39 tt ot 0.097 S 0.048 0.048 0.048 volume TE0'O 2600 S10O 0 0O91O0 Soysqy9TQBL a2uey (90/3) - -- - - - - 700> S00> 0O> 0O> <900 eT Concentrations 3s0ano0Sg JepuedgTEM ueoW 00 STO O - - - - - Mean Mean MeanMean800O010SOIT'ORange Range jo ON0.09 0.006 < 0.006 S 0.003 0.003 - 0.28 V@ 0.020 | | poyzeW 2aonsuosT Ajuo 0.02 0.23 < 0.4 - TO1QU0D wnoeA unoeA unoea 3eM [os1y 13eM soayuL x fon) [ee] (FIBERS/C) METHOD CONTROL CONETRAION ASBETOS mean asbestos concentrations near the axle ranged from less than 0.006 cc to 0.027 cc The aerosol spray method resulted in the highest average fender concentration 0.115 cc This is about 5 times the average fender concentration for vacuum enclosure B and an order of magnitude higher than that for the other three control methods The use of vacuum enclosure B resulted in the highest average axle concentration Dust was observed to escape from the seal of this enclosure during brake cleaning with compressed air One axle sample was six times the highest axle concentration of any of the other controls 5.2.3 Background Sampling Results Indoor ambient arithmetic mean asbestos concentrations as determined by Table 5-5 are compared to arithmetic mean asbestos exposures in Figure for the five control methods evaluated Arithmetic mean asbestos TEM 5-3 concentrations inside the garages were 0.006 cc or less that nearly all the asbestos exposure for the mechanics was and not indoor background asbestos concentrations These data due to job indicate tasks 5.2.4 Outdoor Ambient Sampling Results Outdoor ambient arithmetic Table 5-5 Of 32 ambient of about 0.005 cc mean concentrations were samples analyzed by TEM 0.006 cc or less 24 were less than the LOD 5.2.5 Bulk and Settled Dust Samples A bulk sample of brake dust was collected from each vehicle serviced to determine if the friction materials contained asbestos Each brake dust sample consisted of a few grams of dust from each of the vehicle's rear drums and the front drums of jeeps combined into a single sample vial 43 bulk brake dust samples were collected Bulk samples were analyzed for asbestos by TEM Generally less than 1 percent of the particles present in the bulk brake dust samples was asbestos although several samples contained as much as 1 percent asbestos These results are summarized in Table 5-6 Settled dust from one or more sites within each facility were similarly collected and combined into a single bulk sample The settled dust samples were collected to indicate the potential for building contamination Most of the fibers present in both the brake and settled dust samples were chrysotile asbestos Fewer than one in a thousand asbestos fibers in the bulk brake dust samples were amphibole asbestos Two of seven settled dust samples contained amphibole asbestos one settled dust sample contained 20 percent of total fibers amphibole asbestos possibly from the insulation used on the hot water pipes in the garage Other fibers in both dust samples were determined to be nonasbestos the brake dust and settled 40 i asuey (9/3) 9100 800 GO0O>- <00 Z10O - - - - 00> 700> <00> <00> O0'> qUSTqiy UuBsA DT 10pzNno (9/3) s00 900 Table 5-5 900> WAL Asbetos Aq jo seT Samples Arithmetic Ambient Ambient l 7 L Arithmetic se 1A Z10O 0.02 - 0.012 OL0'>- - - - - B eZueq 0.02 zZ0 '0> 0.04 - 0.12 Z00> queTquy ueRQ yUeTqUY OT 0.03 700 0.02 - 0.010 00 10puyt AOWUTAY SOeqsy jo soj{ dues Tt S t 8 Z ON y @ aqTosve/ynaq AYTT ainsoyTue eansotu AqTuo keads TIA unseA wnsoer unoea 3amK Tosl1ay wt a puepedmieed i armen Le LNZIGVY AMBIENT -(WIL) IVNOSUd HOGNI HSNYE ST@eAT GOHLAW Bg ZZ LAM so}Seqs OWA g@ TOYLNO punSorsAHIeq (09/SY3aid) TONG TeuOsSaeq V SPRAY E-G SOLAESV eaN3Ta SOLO +380 CONTROL CONTROL METHOD 000 42 Control Table 5-6 TEM Analysis of Bulk Brake and Settled Dust Samples Sample type Number of samples Percent asbestos in total dust Percent asbestos of total fibers Percent of fibers > ...m in length Vacuum enclosure A brake dust settled dust Vacuum enclosure B brake dust settled dust Vacuum only brake dust settled dust Wet recycle brake dust settled dust Aerosol spray brake dust settled dust No control brake dust Water hose and solvent brake dust 9 1 11 1 62 1 96 1 6 3 1 1 < NA 54 - 100 85 0.1 - 1 < 0 - 100 60 0.1 - 1 0.1 24 - 100 68 BA NA 83 - 100 99 AA AA 74 - 100 56 - 84 0.1 99 NA 84 17 5 0-6 0-6 0-6 0 0 0 0-3 7 1 - 16 07 0 0 * NA includes fiber bundles not available 43 Prpens While the percentage of fibers longer than 5 ...m for most than about 3 percent the brake dust from a few vehicles vehicles was contained a less substantially greater percentages of fibers longer than 5 ...m No obvious trends were observed e.g. vehicle size which could account for the presence of these long fibers TEM analysis of the bulk brake dust samples showed that the aspect ratio of 90 to 97 percent of fibers was greater than or equal to 5 for each of the five major controls evaluated 5.2.6 Field Blanks One or two field blanks were prepared for each vehicle evaluated and submitted for PCM and TEM analysis Fifty blanks were analyzed by PCM and 34 blanks by TEM these results are summarized in the Appendix Analysis by PCM showed that all blanks were below detectable limits and that 3 of the 34 blank samples analyzed by TEM contained a single asbestos fiber Because of the very low asbestos fiber counts on the blanks no blank correction was made to the TEM sample results 5.3 LARGE VEHICLES Two vehicles with rear wheel brake drums 16 to 17 inches in diameter were evaluated in this study A salt truck was sampled while using vacuum enclosure A and a boom truck was sampled using the aerosol spray method As shown in Table 5-7 fiber concentrations determined by PCM for both large vehicles were below 0.004 cc LOD however asbestos exposures determined by TEM analysis were 0.15 cc for the salt truck and 0.88 cc for the boom truck These results are based on two simultaneous personal samples taken during brake service to the rear wheels of the respective vehicles In Figure 5-4 the results for these two vehicles are compared to the maximum asbestos concentrations TEM measured during brake service to vehicles with 8- to inch drum sizes using the same controls 5.4 REAL SAMPLING RESULTS time data were obtained during most of the brake maintenance jobs evaluated and collected on 26 operators performing brake maintenance jobs vehicles The data collection took place during actual brake maintenance operations and lasted approximately an hour The HAM was located next to personal filter sampler in the breathing zone of the brake mechanic to 36 the The general brake maintenance procedure as monitored using the time instrumentation was 1. The vehicle was driven into the work area and raised off the floor from a few inches to 4 feet 2 The lug bolts and wheel were removed On some vehicles the brake drum was attached to the wheel so it was also removed at this time 44 eT Wod Beuo0siadg(9/}) 70 0O> <00> soxeag qetxv (9/F) Table Table and and Vehicle Wal Drum in 91 90 Personal BUTOAIES eT euo0sijed Truck Salt 16.5 STO 0.15 0.88 Bom suotzejU0D azts (ut) wnad LT S 9T aeqta yonsaz yonal pue BTOYUSA Tes wog soyzeqsy V sanoTue Aeads sotdwesetTdues [o14UOD unoeA Tosiy omy, ouo fiq 45 soTOY@A AWHdS JeTUS 83 0 TOSUAV SA GOHLAW SHONIZ aZae] 0.25 0.05 1IOYHLNO :seanodxe 9k: Zh 0.0 aZIS ENCLOSURE WNYC WONG BY TEM SPRAY Wal soyeqsy Ad -S ANLYSI o'l 420 os'0 c'0 0'0 SIATVN eansta 46 3 The brake drum was removed 4 The brake dust from the brake drum and backing plate were removed using the dust control being evaluated For the wet wash control methods cleaning was started before the drum was removed For vacuum the enclosure and enclosure then A the drum was removed while it was inside cleaned If brakes needed replacement the 5 The brake components were inspected were removed Some control methods vacuum wet brake components removal for additional recycle and wet spray were used during brake dust control and cleaning purposes 6 The new brake shoes and components were installed 7 The brake drum was reinstalled 8 The wheel was remounted and the lug bolts tightened 9 The vehicle was test driven and the brakes were adjusted if needed were taken during each of 26 brake jobs for which From 600 to 1,900 readings concentration and the real data was collected The average relative dust standard deviation for each phase of the brake maintenance job were determined Table 5-8 shows the average relative dust levels reported as the aerosol monitor response in millivolts during the various brake maintenance for each control method The average relative dust concentrations pbheatsweesen the various phases were used to identify the principal sources of dust exposure during brake maintenance 47 OMNES Ta TE Ln Table 5-8 Average Relative Respirable Dust Levels aerosol monitor response in millivolts Vacuum Encl A Vacuum Encl B Vacuum Only Wet Brush Recycle Aerosol Spray Brake Maintenance Phase No Activity Background Remove Wheel Remove Drum Clean Remove Brake Parts Install Brakes Remount Wheel 0.007 0.008 0.008 0.007 0.006 0.012 0.009 0.030 0.018 0.011 0.009 0.012 0.021 0.005 0.022 0.011 0.007 0.009 0.008 0.017 0.008 0.046 0.021 0.007 0.012 0.006 0.021 0.008 0.011 0.027 0.011 0.012 0.012 0.017 Summary Mean Standard Deviation Average TEM cc Number Vehicles Brake Drums Removed Brake Parts Removed 0.008 0.027 0.036 0.013 0.032 0.036 0.008 0.015 0.025 0.011 0.034 0.012 0.009 0.008 0.052 6 9 8 12 32 16 2 6 16 10 2 38 4 22 4 * The time data is in millivolts representing the total light scattered by the brake dust operation there is Since the no simple composition of the dust changes relationship between instrument with reading and TEM cc sample results 48 6. DISCUSSION 6.1 CONTROL PERFORMANCE All the control techniques studied prevented exposures in excess of the OSHA PEL or NIOSH REL as determined using the PCM analytical method 6.1.1 Comparison to Historical Data Roberts et al 3 reported weighted average TWA exposures of about 0.2 cc and peak exposures of about 15 cc while using dry brushing wet brushing or compressed air during brake repair Analyses were performed using NIOSH Method CAM 239 PCM They reported TWA asbestos concentrations during compressed air brake cleaning ranging from 0.03 to 0.19 cc concentrations during wet brush brake cleaning ranged from 0.23 to asbestos exposure using a squirt bottle to wash the 0.28 cc brake drums A reported was 0.21 cc Several subsequent studies have documented asbestos exposures as determined by brake PCM during and O'Kelly found average drum servicing to passenger cars buses and trucks Cheng in a study of motor vehicle repair facilities in Hong Kong exposures of 0.13 cc during compressed air blowing with a maximum of 0.28 cc during dry brushing exposures averaged less than 0.1 cc These results are based on short samples and represented a variety of vehicle sizes In West Germany Rodelsperger et al 41 measured asbestos concentrations during brake repair to passenger cars and found an average exposure of 0.1 cc during compressed air cleaning and 0.09 cc for dry brushing These results were based on personal samples collected for 30 minutes to over an hour and were analyzed by PCM Korhonen 42 Kauppinen and service stations in an evaluation of brake maintenance garages and in Finland estimated for repair of passenger car brakes an average TWA exposure PCM of 0.05 cc during compressed air cleaning and 0.04 cc for dry brushing maximum TWA concentrations for the methods were 0.5 and 0.1 cc respectively For brake repair two cleaning of trucks and buses average TWA exposures were about 0.2 cc and wet cloth cleaning maximum TWA's were about for 0.7 compressed air brushing cc for these methods Figure 6-1 is a comparison of studies during compressed air the average exposure PCM from five historic cleaning with the average exposure for each technique in our study In a 1979 survey compressed air 43 the rear brakes of an automobile were cleaned , The asbestos exposure of that worker was 0.14 cc using as 49 wren HIV AWHdS (9/SHagId) 0. .04.04KINO HSNua OW LSM NOILVYSON Bi ZA (| WE FER HISTORIC DATA STUDIES 800 wod SGOHLIW 4q seanodxe 200 1OHLNOD SAIGNLS Jeqta $ 1-9 .008 WOYS ean3aty VLVd 4<00 00 OIHLS. 50 determined by TEM using SAED and energy dispersive ray analysis and included all fibers During this approximately hour sample surveyperiod brakes of this vehicle were serviced In another only the rear period in 1979 two personal samples were taken while drum brakes of two vehicles The a mechanic sample for replaced the front disc and the first vehicle showed an rear asbestos concentration TEM of 0.20 cc hour sample and 0.95 cc hour sample for the second The backing plate was cleaned with compressed air and a Stoddard solvent mixture A statistical comparison was made between our study results for the servicing of vehicles such as pickup trucks vans automobiles and several large trucks and historical data for brake servicing using compressed air dry brushing and squirt bottles types and facilities study then exposures It showed that if variables such as workers vehicle had been controlled between our study and the historical in our study would be significantly lower 0.005 for PCM exposure data 43 The TEM exposure data from , those of the 1979 surveys study were an order of magnitude lower This again demonstrates a major difference between exposures when using the controls evaluated in our the methods used in the earlier studies than study and 6.1.2 Comparison to No Controls No facility could be found in our study where compressed air except within a to clean vacuum enclosure or dry brushing were used study of Pennsylvania brake operations Moore vehicle found that brakes only one In of 31 brake shops used compressed air To estimate a base line exposure for our study however an uncontrolled brake repair operation the brake drums were dropped on the floor to displace the dust was sampled The measured asbestos exposure as determined by PCM and TEM for the uncontrolled method was comparable to the five major control methods Although the mechanic's exposure was low there is a potential for build of asbestos contamination in the garage Furthermore neither the brake drum nor the brake assembly was cleaned as well as desired Because the uncontrolled procedure was measured for only one vehicle no statistical comparison was made between the results for this method and the five control methods evaluated 6.1.3 Comparison to Indoor and Outdoor Ambient Levels Personal sample concentrations during brake repair were significantly higher than indoor background levels as determined by PCM 0.03 and TEM 0.005 when using the aerosol spray method personal sample concentrations TEM were higher than indoor background levels when using vacuum enclosure B 0.06 Personal sample concentrations during brake repair for the other controls methods were not statistically different than indoor background levels based on both PCM and TEM results Asbestos as determined by TEM was detected on only 25 percent of the outdoor ambient samples thus no statistical comparison to indoor background concentrations could be made However average outdoor and indoor ambient asbestos concentration measurements were about the same 51 TS ue 6.1.4 Effect of Vehicle Type Drum Size and Number of Drum Brakes ren sy Most of the vehicles evaluated in the study were automobiles and light trucks with 8- to inch drum sizes however two large vehicles with 16- to inch drums were also evaluated Personal sample concentrations during brake service to the latter as determined by PCM were at or below the detection limit 0.004 cc as were brake service to the most of smaller the personal sample vehicles Although concentrations PCM during there was no difference based on PCM measurements between large vehicles and small and medium size vehicles asbestos vehicles exposures as determined by were an order of magnitude TEM during brake service to the large greater than during brake service to vehicles with smaller drum sizes Larger brake shoe surfaces and drums probably asbestos contain more residual dust and provide a much emissions In addition the drum assembly of greater source the large salt of truck was so large and difficult to remove that the vacuum enclosure A could not be placed over it until the drum was removed Statistical analysis of TEM data showed that when using the aerosol spray method the average personal sample concentration for brake repair of the large boom truck was significantly higher than the highest exposure during brake repair of the other vehicles 0.01 but for vacuum enclosure A the exposure during brake repair of the large vehicle was not shown to be statistically different than that for the smaller vehicles Except for the effect of drum size differences in personal and source sample concentrations due to vehicle model miles traveled number of drums per vehicle etc. were small 6.2 CONTROL METHOD DESIGN STRENGTHS AND WEAKNESSES 6.2.1 Vacuum Enclosures The two vacuum enclosures evaluated surround the brake assembly during cleaning The front of the enclosures protect the brake mechanic even if seals around the axle at the back are not tight The enclosures allow the the use of compressed air for more thorough cleaning however if the seals are not tight asbestos can be blown into the shop and create a general room hazard Work practices which may affect worker dust exposure are 1 use of the pressurized air hose may force open the vacuum enclosure seal in the back and release airborne dust from the chamber 2 incomplete air washing and vacuuming of brake dust 3 dust trapped behind brake components may become airborne during change and replacement and 4 poor maintenance of the vacuum enclosure unit e.g. not changing filters regularly and incomplete cleaning of chamber Vacuum enclosure A was large enough to accommodate the entire brake assembly of most of the vehicles while removing the drum The axle source sample concentrations TEM for cars pickup trucks and vans were all less than 0.03 cc indicating that brake dust was not blown out the back flaps Vacuum after the drum enclosure B a smaller unit fit around the brake assembly only was removed and did not form a tight seal As a result both personal and 52 area fender and axle asbestos concentrations enclosure B than for enclosure A. TEM were slightly higher for Vacuum enclosure A has a large clear plastic enclosure which provides good visibility Tools such as a hammer can be placed inside the enclosure before starting the brake job The two glove entry ports make it possible to do more tasks in the enclosure This enclosure could not be used while removing the drums of the large vehicles drum size 15 inches for two reasons 1 the drum is an integral part of the wheel and must be removed with the wheel and 2 the drum is so large and heavy that the mechanic cannot remove the drum while inside the hood An advantage of using vacuum enclosure while the vacuum is running and thus A is that it is under negative pressure the potential for airborne asbestos to leak from the chamber is reduced However workers need to be trained to operate and maintain the vacuum enclosure unit or they may increase their personal exposure to brake asbestos through poor work practices e.g. improper use of the compressed air hose may force open the seal around the axle and blow dust out of the unit Workers stated that brake cleaner fluid was sometimes applied to the enclosure unit brake parts to suppress off the brake housing brake dust after taking the vacuum Brake inspection took approximately 16 minutes and brake inspection and replacement took 25 minutes per wheel A minute or two of this time was required to roll out either vacuum enclosure and put it in place After 4 months of operation averaging four brakes inspections or replacements week the vacuum filter was found to be about half full per From an ergonomic point of view vacuum enclosure A is somewhat cumbersome to use and maintain It is too big in some instances to be easily maneuvered between cars the height of the base does not permit the unit to be used as close to the floor as would be desirable especially for large trucks the inside of the plastic dome is hard to clean and the outside is prone to scratches and smears which may impair visibility there are no brackets or other provisions to conveniently store the vacuum hose after use Based on a recommendation from our survey a hook was fabricated to keep the hose off the floor and in good repair It was also noted that design of the gloves especially at the wrists may restrict workers who have large muscular hands from being properly fitted into the gloves However the workers thought that the vacuum filter was effective With vacuum enclosure B it was necessary to remove the brake drum from the vehicle before the enclosure could be applied to the brake assembly The rubber seal at the back of the encapsulation cylinder was poorly designed because it was easily deflected by the compressed air stream The brake components inside of the cylinder were poorly illuminated It was difficult to change the gloves to accommodate size and glove hand left or right The vacuum unit was bulky this made it difficult to maneuver and use in tight work spaces 53 In addition workers felt this unit was heavier than a vacuum enclosure device they had used previously Asbestos concentrations as high as 0.164 cc TEM for the axle sample is indicative of brake dust escaping during air washing when the air gun is pointed at the enclosure seal in the back of the enclosure The manufacturer has recently changed the iris seal to one constructed with overlapping panels) 6.2.2 Vacuum Only The filter equipped vacuum unit substantially controlled asbestos exposures the personal exposure concentrations averaged 0.007 cc as determined by PCM and 0.022 cc as determined by TEM This unit is not limited by drum size and can be used at any stage of the brake maintenance operation This control method eliminates the need to dispose of a liquid residual that wet methods require however the unit does require periodic maintenance including replacement of the HEPA filter The filter equipped vacuum unit does not provide for the use of compressed air and may result in less thorough cleaning than with the enclosure method The relatively low axle and fender asbestos concentrations as determined by TEM indicate that little force compared to compressed air or the pressurized wet spraying is applied in vacuuming the drum The highest fender or axle concentration TEM was 0.020 cc The vacuum unit with the HEPA filter was effective for small and medium size vehicles but it was not evaluated on large vehicles It may be a suitable control when replacing brakes for such vehicles because no enclosure is used the control is not limited by wheel size Additional research on larger vehicles is needed This unit appeared to be easy to use and effective for dust control from an ergonomic point of view However the effectiveness of the unit as a control is likely to vary with the work practice used and as was previously discussed may vary with the size of the vehicle One work practice which increased the contact with asbestos fibers fibers which can become airborne and enter the breathing zone occurred when after the disassembly small parts springs screws etc. were hand held to vacuum them Another practice observed to increase the dust levels occurred when the mechanic wiped his hands with a dry rag 6.2.3 Wet Recycle Low personal exposures and fender and axle concentrations as determined by TEM showed that the wet recycle unit controlled asbestos exposures No asbestos fibers as determined by TEM were found on any of the personal samples Regular changing of the cleaning solution is needed for maximum effectiveness Since there is no control during drum removal such as an enclosure the mechanic should allow cleansing fluid to flow between the brake drum and brake support plate before the drum is removed After the brake drum is removed the wheel hub and the back of the brake assembly should be 54 thoroughly wetted to suppress dust The brake support plate brake shoes brake components used to attach the brake shoes also should be thoroughly washed before the operator starts to remove the old shoes and The wet recycle control method was evaluated only on jeeps sizes of 9 to 11 inches however these vehicles had drum brakes which had drum on all four wheels Higher asbestos exposure may occur during brake inspection and repair to vehicles with larger drum sizes when using this control method further research on large vehicles is needed 6.2.4 Aerosol Spray The aerosol spray method showed that asbestos exposures based on breathing zone samples TEM were well controlled however fender concentrations as high as 0.166 cc TEM indicate that asbestos fibers are being released during the brake job Holding the spray can too close to the brake assembly while spraying could increase asbestos emissions The following technique appeared to lower dust exposures Spraying was started about 18 inches from the brake surfaces After the surfaces were wetted the nozzle was moved to about 12 inches from the surfaces to clean them The brake components were individually sprayed as they were successful the mechanic needs to spray application technique The carefully selected to ensure that being removed For this method to be be trained in the least hazardous aerosol solution used for the aerosol spray must be hazardous exposures from solvents or other ingredients do not occur The average time for a one wheel brake replacement spray unit was 30 to 40 minutes The spray tip of maintained to provide a fine spray from the nozzle which blasts upon the brake assembly surfaces task while using the aerosol the applicator needs to be as opposed to a spray jet TEM personal higher using sample results Table 5-7 and the aerosol spray method on a Figure 5-4 were substantially vehicle having inch brake drums a tandem wheel vehicle than for vehicles having smaller brake drums /12inches in diameter indicating that the wet spray was not as effective on the large vehicle Not only is the brake surface area greater resulting in greater amount of brake dust that needs to be controlled but the wheel well area is larger making the area to be sprayed less accessible The wheel well acts as a partial enclosure which captures the airborne dust and mist generated during spraying In order to reach the parts and to observe the cleaning operation the mechanic must place his head within the wheel well As result the exposure to higher concentrations of asbestos dust were encountered than when a smaller vehicle is serviced 6.3 RECOMMENDATIONS OF REGULATORY AGENCIES 6.3.1 Occupational Safety and Health Administration OSHA guidelines presented in Appendix F of CFR 1910.1001 46 recommend the use of the vacuum enclosure compressed solvent system and the aerosol 55 spray squirt bottle or nonrefillable spray can methods Because they operate at lower pressures OSHA indicates that squirt bottles or spray cans are preferable to the compressed solvent system Dry and wet brushing methods are considered by OSHA to be ineffective The use of compressed air to blow the brake drums clean is specifically prohibited by OSHA The results of our study demonstrate that when the vacuum enclosure and aerosol spray method were used correctly the mechanics exposure to asbestos was well below the OSHA PEL and NIOSH REL The compressed solvent system was not evaluated Two other techniques studied also showed low exposures for the mechanics a vacuum only unit with HEPA filter and wet recycle with recirculating solution The wet recycle technique observed in our study a brush continuously flooded with a solution of water and a solvent successfully controlled asbestos exposures Unlike the ineffective simple brush methods cited by OSHA the liquid was apparently delivered to the brush at a volumetric flow sufficient to wet the dust without rendering it airborne The filter equipped dust from the brake drum vacuum was used with after it was removed a metal crevice tool to remove from the brake assembly to clean up brake dust that falls to the floor during drum components before the removal of the brake shoes removal to clean the brake and to clean components again as they are removed A simple wet brush method evaluated on a single vehicle resulted in low exposure to the worker However because this result was obtained from a single evaluation it is difficult to ascertain the appropriateness of this method Manual wet brushing may be an effective control measure depending on the skill of the worker gentle application of an adequate quantity of solvent to thoroughly wet the brake dust 6.3.2 U.S. Environmental Protection Agency 47 Guidance for Preventing Asbestos Disease Among Auto Mechanics a publication of the U.S. Environmental Protection Agency suggests the following methods contribute to worker exposure to asbestos dry rag or brush wet rag or brush squirt garden hose and the best control bottles or aerosol spray solvent recirculation systems simple shop vacuum cleaners This publication suggests that approach is to contain brake dust and prevent its release into the work environment it recommends the use of vacuum enclosure equipment The results of our study essentially confirm the performance of the vacuum enclosure method recommended by the U.S. EPA Our study also indicates that the wet brush with circulating solvent and the aerosol spray methods are effective background asbestos the wet methods than in garages measurements were no higher in garages using using the vacuum enclosures All the garages studied using wet methods used care so that all liquid residue was collected in catch basins which were emptied before the solvent was allowed to evaporate Low asbestos exposures were also measured when a single brake inspection was 56 made using the simple our study a garden hose and a shop vacuum cleaner wet brush without a Dry HEPA rag or brush filter were methods and use of not evaluated in 6.4 REAL SAMPLING The NIOSH air sampling methods for asbestos provide an integrated average over the sampling period 2 hours whereas time sampling data exposure provides short exposures 1 minute due to various job tasks The time data obtained from the HAM instrument are a measure of the respirable dust concentration and are not specific for asbestos However correlation of time results with the phases of brake maintenance is a starting point for identifying brake maintenance job tasks which produce increased asbestos exposures Comparison of the relative dust concentrations produced by individual job tasks can be used to assist in the determination of the relative effectiveness of the brake dust control methods The control methods evaluated could be applied to four of six identified phases of brake maintenance drum removal drum and brake assembly cleaning parts removal and installation of the parts and drum None of the control methods were applicable during the removal and however most of the dust generated by remounting of the wheel these tasks was assumed and tire to be from dirt and road dust containing minimal amounts of asbestos These dust concentrations could probably be reduced by running the vehicle through a car wash before brake maintenance was initiated Overall all methods controlled dust release to relatively low average and peak concentrations During brake drum removal time data indicated that enclosure A provided the best control This was especially true when the drums were difficult to remove and required hammering and prying to release them The wet recycle method showed slightly higher dust generation during this phase dust control may be improved if cleaning solution is allowed to flow between the backing plate and the drum before the latter was removed All methods controlled dust release to relatively low average and peak dust concentrations during brake cleaning parts removal and reinstallation 6.5 WORK PRACTICES AND HYGIENE Mechanics should assume that all brake shoes being removed are asbestos shoes Worn nonasbestos brake shoes cannot be readily distinguished from asbestos shoes If the mechanic makes an erroneous assumption that a shoe is of the nonasbestos shoe and relaxes his normal brake dust control procedures increased asbestos exposure may result The operator must be trained in the correct and most effective way to use the control system selected The danger of improper work practices which can increase the worker's potential exposure to asbestos should be explained Some examples are directing an air nozzle at an enclosure seal placing the nozzle of a spray mist too close to the work surface not placing the vacuum nozzle close enough to the contaminated surface turning on the vacuum pumps before 57 positioning the vacuum enclosure over the wheel and leaving them on when removing the enclosure splashing or spilling brake dust contaminated solutions on the floor The control device should always be used and consistent work procedures should be followed Any spills of brake dust or contaminated solutions containing brake dust be cleaned up immediately by either vacuuming or wet mopping For difficult drums that require hammering to loosen a pan with a water in it could be placed beneath the wheel to catch the falling brake should little dust Vacuum enclosure units should be large enough that the brake drum can be removed while the drum is enclosed and should be large enough to allow for hammering when brake drums are difficult to remove because of wear rust or other reasons If drums are too difficult to remove within an enclosure the vacuum nozzle should be positioned beneath the brake drum to capture dust and dirt that falls from it Enclosure systems should have good interior lighting to illuminate the work area The seal should completely enclose the brake drum and backing plate and provide a tight seal around the axle The mechanic should not direct the air gun at the seal After cleaning with compressed air the inside surfaces of the enclosure should be vacuumed to keep the inside clean and maintain visibility Each brake component should be vacuumed as it is removed and the backing plate should be vacuumed after all the components have been removed If a rag is used to wipe dry or clean used brake parts the mechanic should not use this same rag to wipe his hands Wiping of hands with a dry rag was observed to increase dust concentrations in the mechanics breathing zone Water and a suitable soap or detergent should be used to clean the hands Operators should wear a approved respirator when changing filters on vacuum units When using the wet recycle method the wheel hub and back of the brake assembly should be wetted before removing the drum The fluid should be allowed to flow between the backing plate and the inside of the drum to thoroughly wash the backing plate and drum After the drum is removed the wet brush should be used to wash the components being removed The brake washer solution should be changed regularly for maximum efficiency of the unit Respirators or other personal protective equipment may be required when adding the cleaning or wetting agent to the water The manufacturer's recommendations should be followed The aerosol spray method requires only a small piece of equipment however correct work practices are essential If the the spray nozzle is held too close to the brake surface asbestos fibers can become airborne Brake components should be sprayed to saturate the parts as they are removed from the assembly The spray nozzle should be maintained so as to provide a fine spray rather than a jet or stream of liquid A regular maintenance program for the device used to control brake dust should be instituted It should include checking and replacing seals nozzles other hardware and contaminated filters and solutions The deficiencies of any control system such as ineffective seals and the effects due to sprays and 58 air nozzles should be well understood Disposal of contaminated material whether it be filters or solutions should be done in accordance with federal and state regulations Periodic cleaning should be performed to remove asbestos contamination of work benches floors etc. Mechanics should not eat drink or smoke in work areas Asbestos potentially toxic materials can be ingested by these actions and other Personal hygiene such as washing hands frequently and showering at work going home should be uncontaminated street stressed Changing from soiled work clothes into clothing before leaving work provides additional before protection against bringing asbestos into the home environment A laundry service with facilities for cleaning contaminated clothing should be provided for the soiled work clothes When selecting a control system two factors to consider are time and convenience Some systems add several minutes to each brake job thus a mechanic that is paid for each job completed is less likely to use such a system correctly if at all Similarly if the system is awkward or cumbersome it is less likely to be used in an effective manner 6.6 FIBER SIZE AND POTENTIAL HEALTH EFFECTS In this study a total fiber count including fibers not identified as asbestos was obtained by pooling all the personal samples from each of the five major controls The majority of these The results of this pooling are presented in Figure 6-2 fibers are less than 0.1 ...m in diameter and less than 4 ...m in length fibers present The potential health impact of the completely understood However Stanton in brake dust is attempted to estimate not the tumorigenic potential in humans according to a fiber diameter and length matrix Stanton noted that long thin fibers produced the greatest tumorigenic incidence in experimental animals A plot of the fiber sizes measured in this study is presented along with an overlay of Stanton's classification based on his animal studies in Figure 6-2 About 1 percent of the fibers in the samples fit the from our study potential Pott classification of moderate and high tumorigenic ) has summarized other studies concerning the carcinogenic potency of asbestos fibers These studies indicate tumor induction extends to fibers shorter in length than those given by Stanton Pott also notes that although the carcinogenic potential of short fibers may be low many short fibers may induce a tumor as easily as a few long fibers 59 (GZ $9Y care A DIAMETER > 1 4 8 - en cman nA SH3al4 0.1 b> b> b> b> b> | UO}JRIS) Ate -setdues ne FN toe x eo Teuoszed re Ler [Te Te Z L> [> A @) Ne 10j Manet 60 SIVWNV (wn) -0.25| NI WLOL AEARS TIV) 0.25 0 STIVWNY UOTyNGISP JO 1.5 92 LL Zk 3LVY < fe) NI NI RM ne YOWNL Y3als INURE | 0 3LVYe eZTS Y %0 < 8 L fe) fe) Jeqta 2.5 < YHOWNL | 2-9 3DVLNSOYd ALVYSGOW HDIH eanBtd MOT LOW ANIMALS ANIMALS Ge2- TUMOR IN ANIMALS ALISOdINO MODERAT MODERATE RA-TE ANIMALS 9'0< ( Stanton Ref 25 60 7 CONCLUSIONS RECOMMENDATIONS 7.1 CONCLUSIONS All of the five methods tested in combination with the work practices used controlled the mechanic's asbestos exposure during brake servicing to less than 20 percent of the NIOSH REL and 10 percent of the OSHA PEL Personal exposures as determined by PCM were at least an order of magnitude lower than personal exposures reported in the literature for involving compressed air dry brush or wet brush brake cleaninsgersvervice ice operations In the present study brake mechanics were exposed to concentrations ranging from less than 0.004 cc to 0.016 cc counting rules 7400B for hour sampling periods the highest exposure was below the NIOSH REL of 0.1 cc and less than tenth the OSHA PEL of 0.2 cc As long as compressed air cleaning wet brushing or vacuum cleaners without HEPA filters are not used it appears that even simple control measures suffice Sites and methods used in historical studies appeared to be similar to those used in the present study present study The results of the brake repair operations generally support OSHA Guidance for automotive In particular the use of the two engineering control methods - vacuum enclosure methods and the aerosol spray squirt bottle - that were recommended by OSHA resulted in low personal exposures as determined by PCM and TEM analyses However the present study found the vacuum only unit with HEPA filter and wet recycle with recirculating solution methods also showed low personal exposures for the mechanics These latter two methods were not mentioned in the OSHA Guidance Brake mechanics are exposed to average concentrations of asbestos fibers ranging from less than 0.013 cc to 0.052 cc by TEM for the controls used in the present study excluding two vehicles with 16 to inch drum sizes Results obtained by TEM include asbestos fibers of all sizes Although TEM results are higher than PCM results because of the greater sensitivity both analytical methods yield ranges of results well below the OSHA PEL for small and medium size vehicles such as automobiles and light trucks Brake service to two heavy duty trucks two 16- to inch drum size showed higher asbestos concentrations than for smaller size vehicles as determined by TEM The large trucks had greater brake shoe surface area and bulkier drums Also controls such as the vacuum enclosures observed in our study could be applied for fewer brake service tasks Although mechanics were exposed to levels of asbestos fibers well below the NIOSH recommended exposure limit for asbestos as determined by PCM the TEM results may indicate that a greater potential exists for asbestos exposure while servicing heavy duty trucks 61 Except for the effect of drum size differences in personal and source sample concentrations as determined by TEM among the vehicles evaluated were very small Differences with respect to mileage vehicle model year of manufacture etc. were not observed Vacuum enclosure units are the only type that provide for containment of the brake assembly during drum removal These enclosures come in a variety of sizes which limit their use to certain brake drum sizes Vacuum enclosure A was large enough to allow the drums of autos vans and pickups to be removed and replaced within the enclosure and the enclosure therefore helped contain asbestos emissions during these tasks The glove vacuum enclosures Enclosure A are superior for difficult drums because a hammer and other tools can be manipulated within the enclosure Compressed air can be used in the vacuum enclosures to remove brake dust adhering to the brake components and the shoes However when it is pointed at the back of the enclosure the compressed air blast may be strong enough to deflect some seals resulting in the escape of brake dust through the seals Vacuum enclosure manufacturers could incorporate a means to regulate the air pressure in compressed air cleaning hoses Because brake dust is usually collected dry vacuum enclosures present a potential problem of asbestos exposure during the maintenance of the enclosure and the replacement of the vacuum filters Vacuum enclosures were readily used and well accepted by the att mechanics observed in this study but their use did add several Fret to the time needed to complete a brake job A hook for hanging was designed and added to vacuum enclosure A as a result of our RNA hook was very beneficial according to mechanics on a follow extra minutes the power cord survey This visit The need to illuminate the inside of both vacuum enclosure units was noted TB AT filter equipped vacuum cleaners can be used on brakes of any size These a systems do not use compressed air nor do they generate dust that must be RAREERI contained as do the vacuum enclosure systems However the drums must be hae tt SemnbtCA removed before the vacuum cleaner can be used thus there is a potential for Md ah asbestos release during drum removal They do not clean the brake components f SEL as effectively as some other systems and require small vacuum nozzles to reach smaller parts of the brake assembly ANA The wet recycle system can be used on all sizes of brake drums Limited se wetting of the brakes can be accomplished with the drum in place Dust that ame ym otherwise would have fallen to the floor is wetted and collected in the catch tence basin beneath the wheel This may provide better control when difficult drums are encountered The low velocity delivery of the wet recycle fluid effectively cleans the brake components The contaminated fluid provides a dust free though bulkier method of disposal The principal advantages of aerosol spray systems are low cost and the capability for to ensure that use the on all sizes of sprayer is at a brake drums Care must be taken initially proper distance from the brake to wet the brake surfaces but vigorous spraying must be prevented so that dust will not be suspended The effectiveness of the solvent spray systems as an exposure 62 control method appears to be more dependent techniques In some cases the solvent may component on work contain practices than the other potentially hazardous The asbestos exposure for the uncontrolled method the brake drums were dropped on the floor to displace the dust was comparable to the five major control methods Although the mechanic's exposure was low there is a potential for build of asbestos contamination in the garage Furthermore neither the brake drum nor the brake assembly was cleaned as well as desired Although PCM exposure data in our study can be compared to the OSHA PEL NIOSH REL and historic exposure results only TEM results provide for fiber identification and allow comparisons between vehicle types drum sizes control methods and between personal sample concentrations and ambient or indoor asbestos concentrations This is of particular importance in brake servicing since most fibers are too small to be measured and counted by PCM Fiber size distribution for all fibers including those not identified as asbestos showed that only 4 percent of the service would have been counted using PCM fibers measured Furthermore 90 during brake percent of the fibers identified by TEM had an aspect ratio of 1 or greater Fibers in dust samples obtained from the brake drums tested in this study were mostly chrysotile fibers appeared to have nonasbestos brake shoes of 40 of the 43 The other three vehicles vehicles 7.2 RECOMMENDATIONS 7.2.1 Engineering Controls and Work Practices Engineering controls and good work practices should be implemented at all times during brake servicing Because of the health hazards associated with asbestos exposure these actions are warranted even when the worker believes that the brake shoes do not contain asbestos Several types of control systems or methods can effectively reduce exposure to asbestos during brake servicing When selecting a particular type of control system or method the employer should consider the number and types of brakes jobs to be performed daily and weekly If the system or method selected is awkward or cumbersome to use it is less likely to be used in an effective manner Several control be effective in followed systems reducing methods and exposures if work practices observed in this study the following precautionary steps are can Enclosure systems should fit completely around the brake drum and backing plate and should provide a tight seal around the axle The system should have good interior lighting to illuminate the work area The inside of the enclosure should be large enough for the worker to 63 manipulate any tools that may be needed when brake drums are difficult to remove because of wear rust etc. The vacuum should be turned on before positioning the enclosure over the wheel and it should remain left on while removing the enclosure e For wet recycle methods the wheel hub and back of the brake assembly should be wetted before the drum is removed The fluid should be allowed to flow between the backing plate and the inside of the drum to thoroughly wash the backing plate and drum After the drum is removed all components should be washed and cleaned with the brush e The aerosol spray method is relatively small and easy to use however the spray nozzle must not be held close to the brake surface to avoid the airborne dispersal of asbestos e When using vacuum systems each brake component should be vacuumed as it is removed Once all the components have been removed the backing plate should be vacuumed For drums that are difficult to remove and require hammering to loosen a pan filled with water should be placed beneath the wheel to catch the falling brake dust A regular maintenance program should be instituted for the device used to control brake dust 7.2.2 Training and Education Information about job hazards should be disseminated through a training program that describes how to do a task properly how each work practice reduces potential exposure and how the worker benefits from such a practice Workers who can recognize hazards and know how to control them are better equipped to protect themselves from unnecessary exposure Training and work practices must be frequently reinforced Regardless of which control system the correct and most effective way from using the following practices accidental exposure to brake dust is selected the worker must be trained in to use it Workers should be discouraged since they often increase the risk of e Directing an air nozzle at an enclosure seal oe sre e Placing the nozzle of a spray mist too close to the work surface Placing the vacuum nozzle too far from the contaminated surface to effectively collect all loose dust Spilling brake dust or contaminated solutions on the floor 64 7.2.3 Sanitation Workers should not eat drink or smoke in work potentially toxic substances can be ingested by areas Asbestos these actions and other The use employer should provide washing facilities and encourage workers to them before eating smoking or leaving the work site Workers should not wipe their hands with the same rag used to wipe or clean brake parts since this may release brake dust from the rag Any spills of brake dust or contaminated solutions containing brake dust should be cleaned up immediately by vacuuming or wet mopping The work area should not be cleaned with dry sweeping or air hoses Collected wastes should be placed in sealed containers with labels that indicate the contents Cleanup and disposal should be conducted in a manner that prevents worker contact with wastes and complies with all applicable Federal State and local regulations 7.2.4 Protective Clothing and Respiratory Protection The employer should provide and require the use of work uniforms or overalls Lockers or other closed areas should be provided to store work clothing separately from street clothing All work clothing should be collected at the end of the work shift for laundering Respirators should be worn during specific work tasks e.g. changing filters on vacuum units or whenever the potential exists for airborne exposure to asbestos Selecting the appropriate respirator depends on the specific contaminants and their concentration in the worker's breathing zone Only a NIOSH approved respirator should be selected for use in accordance with the most recent edition of the NIOSH Respirator Decision Logic When respirators are used a complete respirator protection program should be instituted as set forth in 29 CFR 1910.134 * Code of Federal Regulations 65 8 REFERENCES Dubrow Robert and David Wegman Setting Cancer Research and Control Synthesis of Disease Surveillance Studies Journal of Priorities for Occupational the Results of Occupational the National Cancer Institute 1123-1142 1983 NIOSH Survey Analysis and Supplemental Tables National Occupational Hazard Survey Vol III DHEW PHS CDC DHEW NIOSH Publication No. 78-114 Cincinnati OH 1977 Roberts Dennis R. and R. D. Zumwalde Asbestos Exposure Assessment for Brake Mechanics DHHS PHS CDC NIOSH Industrywide Study Report 32.4 Cincinnati OH November 1982 Keasbey and Mattison products catalog Ambler PA 1926 Carroll W.G. The Manufacture of Brake Linings 414-417 August 1962 British Plastics Anderson A.E. R. L. Gealer R. C. McCune and J. W. Sprys Asbestos Emissions from Brake Dynamometry Tests Society of Automotive Engineers Pub No. 730549. Presented at Automotive Engineering Meeting Detroit MI May 14-18 1973 White Andrew J. Brake Dynamics An Introduction to Brakes at the Inspection Station Level Chapter 11 pp 463-472 Motor Veh Resh of N.H. Lee NH 1968 Rohl Arthur N. Arthur M. Longer M. S. Exposure During Brake Lining Maintenance Research 110-128 1976 Wolff and I. Weisman Asbestos and Repair Environmental Friction Materials on Automobile Brakes Fleet Owner August 1963 10 PEI Associates Inc. Office of Pesticides 1985 Asbestos and Toxic Dust Control Substances in Brake Contract Maintenance EPA No. 68-02-3976 11 Williams Ronald L. and Jean L. Muhlbaier Asbestos Brake Emissions Environmental Science Department General Motors Research Laboratories Warren MI Environmental Research 70-82 1982 66 12 13. Inoko Masanori and Kyoko Arisso Determination of Chrysotile Fibers in Residual Dust on Road Vehicle Brake Drums Institute of Environmental Science and Technology Yokohama National University Yokohama Japan Environmental Pollution Series B 249-255 1982 Rohl Arthur N. Letter dated April 11 1979 from Dr. Rohl to Robert Magdelain President Nilfisk of America describing the results of tests run on the Nilfisk system 1979 14 Rohl Arthur N. Letter dated October 12 1984 from Dr. Rohl to Jim Clayton President Clayton Associates tests run on the Clayton system 1984 Inc. describing the results of 15 Newhouse M. and H. Thompson Mesothelioma of Pleura and Peritoneum Following Exposure to Asbestos in the London Area 261-269 1965 Brit J. Ind Med 16 McDonald A.D. et al Epidemiology of Primary Malignant Mesothelial Tumors in Canada Cancer 914-19 1970 17 Greenberg M. Brit J. Ind and T.A. Lloyd Davies Med 91-104 1974 Mesothelioma Register 1967-1968 18 Lorimer W.V. A.N. Rohl A. Miller W.J. Nicholson and I.J. Selikoff Asbestos Exposure in Brake Repair Workers in the United States Mt. Sinai J. of Med 207-218 June 1976 19 20 Bader M.E. R.A. Bader A.S. Teirstein A. Miller Pulmonary Function and Radiographic Changes in 598 Duration of Exposure to Asbestos Mt. Sinai J. of and I.J. Selikoff Workers with Varying Med 492-500 1970 Davis J.M.S. and Heated Chrysotile the Body Cavities 339-353 1973 S.W. Coniam Experimental Studies on the Effects of Asbestos of Mice and Automobile brake Lining Dust Injected Experimental and Molecular Pathology into 21 22 Koshi K. H. on Serpentine Hayashi and Minerals in H. Sakabe Biological and Mineralogical Studies Heat Treated State Ind Health 66-85 1969 Pott F. F. Huth and Dusts in Experimental 313-315 1974 K.H. Friedricks Tumorigenic Effects of Fibrous Animals Environmental Health Perspectives 23 24 Pott F. F. Huth and K.H. Friedricks Tumorigenic Effects of Fibrous Experiments Concerning the Carcinogenic Effects of Fibrous Dusts Interpretation of Results Considering the Carcinogenesis in Humans Annales d'Anatomie Pathologique Paris 237-246 1976 Davis J.M.G. Pleural Cavity The Fibrogenic Effects of Mineral Dusts Injected into of Mice British Journal Exp Pathology 190-201 the 1972 67 25. Stanton M.F. M. Layard A. Tegeris E. Miller M. May and E. Kent The Carcinogenicity of Fibrous Glass Pleural Response in the Rat in Relation to Fiber Dimension J. Natl Cancer Institute 587-603 March 1977 26 NIOSH Criteria for a Recommended Standard Occupational Exposure to Trichloroethane Methyl Chloroform DHEW NIOSH Publication No. 76-184 Cincinnati OH 1976 27. NIOSH Registry of Toxic Effects of Chemical Publ No. 83-107 Cincinnati OH 1983 Substances DHHS NIOSH 28 NIOSH Occupational Health Guidelines for NIOSH DOL Publ No. 81-123 Cincinnati Chemical Hazards OH 1981 DHHS 29 USDOL OSHA Occupational Exposure and Actinolite Final Rules 29 CFR Register 22612 June 20 1986 to Asbestos Tremolite Anthophyllite 1910.1001 and 29 CFR 1926.58 Federal 30 USDOL OSHA Amendment to Occupational Exposure to Asbestos Anthophyllite and Actinolite Final Rules 29 CFR 1910.1001 Register 35610 September 14 1988 Tremolite Federal 31 NIOSH Revised Recommended Asbestos Standard Education and Welfare DHEW NIOSH Publ No. December 1976 U.S. Department of Health 77-169 Cincinnati OH 32 33 NIOSH Statement of the National Institute for Occupational Safety and Health the Public Hearing on Occupational Exposure to Asbestos June 21 1984. Testimony on Proposed Rule Making at OSHA Hearings 1984 NIOSH Method 7400. NIOSH Manual of DHHS PHS CDC DHHS NIOSH Publ August 15 1987 Analytical No. 84-100 Methods Third Edition Vol 2 Cincinnati OH 34 Leidel N. A. K. A. Busch and J. R. Lynch Occupational Exposure Sampling Strategy Manual DHEW NIOSH Publication No. 77-173 1977 35 36 NIOSH Method 7402. NIOSH Manual of Analytical Methods DHHS PHS CDC DHHS NIOSH Publ No. 84-100 Vol 2 August 15 1987 Third Edition Cincinnati OH Burdett Garry J. Technique for the and Anthony Analysis of P. Rood Asbestos Membrane Transfer Fibers or Other Inorganic Particles by Transmission Electron Microscopy Environmental Science and Technology American Chemical Society 643-649 1983 37. Shtrom .: January 28 Personal Communication 1988 PEI Chester Road Cincinnati OH 68 38. NIOSH Quality Assurance and Laboratory Operations Manual DPSE Cincinnati Ohio August 1988 Revision 5 39 Nilfisk of America Inc. Product Information Malvern PA 19355 40 Cheng V. K. I. and F. J. O'Kelly Asbestos Repair and Servicing Industry in Hong Kong 104-106 1986 Exposure in the Motor J. Soc Occup Med Vehicle 41 Rodelsperger K. H. Woitowitz Asbestos 63-72 1986 Jahn B. Bruckel J. Manke R. Paur and H. Dust Exposure During Brake Repair Am J. J. Ind Med 42 Kauppinen T. and Korhonen Exposure to Asbestos of Automotive Vehicles by Different Methods Am 499-504 1987 During Brake Maintenance Ind Hyg Assoc J. 43 Roberts Dennis R. Alignment Service 32.56 Cincinnati Industrial DHHS PHS OH 1980 Hygiene Report Asbestos CDC NIOSH Industrywide Reading Brake Study Report and 44 Roberts Dennis R. Industrial Shop DHHS PHS CDC NIOSH Cincinnati Ohio 1980 Hygiene Report Asbestos Industrywide Study Report Allied 32.58 Brake 45 Moore L.L. Asbestos Exposure Associated with Automotive Brake Repair in Pennsylvania Am Ind Hyg Assoc J. A12 January 1988 46 USDOL OSHA Occupational Exposure to Asbestos Tremolite Anthophyllite and Actinolite Final Rules 29 CFR 1910.1001 and 29 CFR 1926.58 Federal Register 22753-54 June 20 1986 47 USEPA Guidance for Preventing Asbestos Disease Among Auto Mechanics USEPA Publ No. 86-002 Washington DC June 1986 48 Pott F. Asbestos Some Aspects on the Dosimetry of the Carcinogenic Potency of and Other Fibrous Dusts Reinhalt Luft 486-490 1978 69 Appendix Fiber Counts on Filter Blanks Control PCM Number of Filters Number of Fibers Detected Number of Filters TEM Number of Fibers Detected Vacuum enclosure A 12 0 10 2 Vacuum enclosure B 13 0 6 0 Vacuum only 7 0 Wet recycle 12 0 Aerosol spray 7 0 7 1 6 0 5 0 Total 51 0 34 3 US US GOVERNMENT PRINTING OFFICE 1989-749-349 70