Document jmVKKO3bXORg0dZqvrgaG828N

FILE NAME Brakes BRK DATE 1982 Nov 22 DOC BRK117 DOCUMENT DESCRIPTION NIOSH Report - Industrial Hygiene Summary of Asbestos Exposure Assessment For Brake Mechanics INDUSTRIAL HYGIENE SUMMARY REPORT OF ASBESTOS EXPOSURE ASSESSMENT FOR BRAKE MECHANICS REPORT WRITTEN BY Dennis R. Roberts Ralph D. Zumwalde DATE OF REPORT November 22 1982 ~ REPORT 32.630 2.60 Industrial Hygiene Section Industrywide Studies Branch Division of Surveillance Hazard Evaluations and Field Studies . National Institute for Occupational Safety and Health Cincinnati Ohio PRODUSED BY U.S. DEPARTMENT OF COMMERCE NATIONAL TECHNICAL INFORMATION SERVICE SPRINGFIELD WA 22161 - ABSTRACT In order to define the extent of gas and particulate emissions from automotive brakes and clutches a combination separation and storage collection system was devised Unique emissions collectors for both disc and drum brakes and for a clutch were conceived designed and built as the main embodiment of this instrumentation The hardware was installed installed on a vehicle which was then driven through various test cycles to detar- mine the extent and type of brake emissions generated at low and high operating temperatures Traffic Test as well as Typical driving conditions such as the more abusive driving conditions such as Detroit fade its were included both Typical disc and original equipment and aftermarket friction materials for drum brakes were used in the tests Brake relines were made to simulate typical consumer practices The brake emissions generated were removed from the various collectors and mass balances were performed The particulates were processed and analyzed by a com bination of optical and electron microscopy to ascertain the asbestos content and the asbestos particle size distribution in the year debris Comparisons drum brakes of emissions and original from new and used friction materials dise and equipment and aftermarket materials were made the Finally an estimate was made of of the vehicles in the country of the asbestos is converted the Lotal emission of ac tos by all on the average more than 99.7 purcent contribution to the atmosphere is 5060 pounds or 3.2 percent of the total asbestos emissions 111 ent eset welt Hygiene Summary Report of Asbestos Industrial Hygiene Mechanics Assessment Assessment for Brake Exposure National Inst for Occupational U.S. Cincinnati OH Safety and Health PB87-105433 22 Nov 82 U.S. Department of Commerce National Technied formation Service COMESCOMESCOMES COMES ey rd 2 DOCUMENTATION 50277 1. REPORT O. o i DOCUMENTATION DOCUMENTATION ! REPORT PAGE Industrial Industrial Assessment Summary Report of Asbestos Exposure Hygiene Report No. IWS for Brake Mechanics 7. R Aut. hen Roberts and R. D. Zumwalde q Division SurvoefillaSncuerSuvrveiellaincelSurlveilaance nSucrveeillanceHazard Division of Health NIOSH U.S. Department Cincinnati Ohio Evaluations and Field and Human Services 1 PB87ENTE Asian Re PB87 105438 105438 1 feenn 82/11/22 82/11/22 82/11/22 ry i AS | 4 & Pestermnang Orgenszstsn foot. 32-4A 18 Prerent/T 200 (Were Unt me, Studies ol Gee or Gres e me 2 a Ta, Lpomrerng Orgenusenn Reems ont Aderone 1s Tren of Reger & Purwd Caceres Same as box 7 - _| 1h Suswememery Hates automotive collected and analyzed for both Time ta Personal Personal Personal and Personal and general area air samples were fiber concentrations to which brake Weighted Average TWA and peak asbwehsitloes on13t3h2e 2j1o4b Of the six facilities examined mechanics would likely be exposed service shops three were municipal garages and one was & were determined from two were automotive brake Asbestos fiber content and size recommended limits private fleet service g13arTaWAg'es determined for mechanics the NIOSH micron in bulk samples Of the micrometers of 0.1 fibers centimeter However even these cleaning USHA methods produced fiber length with the exception of vacuum cleaning all all The OSILA ceiling fibers standards levels near the NIOSH recommended ceiling which when is 0.5 air cleaning was used The tvice and clutch NIOSH was exceeded Fibers possible an area be designated Vacuum cleaners with posted signs concerning asbestos danger be used for repairs and servicing air filter systems should with high efficiency particulate and clutch areas A equipped brake backing plates assemblies cleaning the brake drums should be initiated protection program personal protection respiratory 17. Dems ssntyue oe Queereeers x & Publication Publication NIOSH Study IWS Region Survey Publication NIOSH Author Automobile Automobile repair Asbestos Asbestos 6. COSATI fotasQrere 1h Awenettey Seen. Gen 08-28.18 LS Security Close (The Reserd RS.esertty Close (Thee Puget Jen mavens on Soruns fi. Re. of Peeve og ms. rae orreemas, poems ITT wns38 Supremes of Commnene Se DISCLAIMER does not constitute endorsement by names or products Mention of company for Occupational Safety and Health the National Institute 11 ~ a ABSTRACT _ The National Institute for Occupational Safety and Health has conducted to characterize airborne asbestos exposures and industrial hygiene surveys brake work practices for mechanics Personal and general area air samples were collected and analyzed for Time Weighted Average TWA and peak asbes- Bulk samples were collected and analyzed for as- tos fiber concentrations ay and All size All samples were analyzed by optical CPT bestos fiber content microscopy TEM The TWA and peak exposure levels and transmission electron varied with the assembly cleaning methods and time required to perform TWA's for mechanics exceeded NIOSH recommended * cleaning Eight of thirteen standards of 0.1 fibers 5 um in length fibers but all were within current Occupational Safety and Health Administration regulations 2 fi- bers Fiber levels for all cleaning methods except vacuuming were e neare the NIOSH recommended ceiling of 0.5 fibers Two of the peak san- air cleaning was used had fiber levels that ples collected when compressed exceeded the OSHA ceiling of 10 fibers General area TWA's were similar for all facilities 0.05 to 0.25 fibers TEM analysis indicated lower OPT in most samples and revealed that 80 of the fiber concentrations than total fiber population total size was 1.7 um length was 5 um long The geometric mean anadnd0.1d5iaummetdeirameter TEM analysis chrysotile fiber showed that 30 20 forsterite and 50 unknown The data of the fibers were chrysotile show excessive brake assembly asbestos fiber exposures during brake servicing cleaning therefore vacuum cleaning systems and especially NIOSH ap- are recommended to reduce asbestos exposure proved respiratory protection levels within NIOSH limits 111 F ef ED Ae Rae OT CONTENTS Abstract jocenee eee eeeee eet EEE EEE iii ECC serene ceccecscscccsenccel Linings Introduction Brake Materials Products and Historical Development of Usage csccecececsecenneceeeseesd Friction Products Requirements for Brake and Manufacturing Processe Types of Brake Linings Practices History Brake Lining and Repair and Maintenance Surveyed ... 10 Selection of Facilities .10 of Brake Servicing Operations Description Sample Collection and Analysis Methods 11 Airborne Sampl ceee cccescss ecceveseel Bulk Samples Work Practices Characterization Compressed Air Characterization .13 Blow Compressed Solvent Mist .13 Dry Brushing tt .13 het Brushing Brushing ... Squirt off . ce cccccecvceceseeseld Vacuum Cleaning cccsrcessseresececeefi Discussion Survey Results and 15 Asbestos Exposure Levels 17 TEM Fiber Characteri ..... Bulk Brake Dust scence eseeersces cee Trace Metal Potential Health Analysis Analysis 23 Effects from Asbestos Exposure . 25 Summary sees esse ee 26 Conclusion see 28 Recommendations seccceccececceccesrsersssensesesnees se TT Appendix References of Individuals Facilities Appendix Description Procedures for Asbestos Brake Recommended Asbestos Appendix and Clutch Servicing . TABLES Results es .16 ..... 1. Fiber Air Sample & Optical Microscopy Analysis 2. Comparison Between TEM .20 ess ....... 3. Fiber Size see ede 4 Trace Metal Analyses ! INTRODUCTION One of the objectives of the National Institute for Occupational Safety and Health NIOSH is to evaluate environmental exposures of working populations through industrial hygiene field surveys Accordingly NIOSH conducted comprehensive industrial hygiene surveys to characterize dust exposures resulting from vehicle brake servicing operations make a thorough assess- ment of work practices utilized and document the types of personal protective equipment used Of particular interest was the potential for ex- to asbestos fibers which could be generated by these types of opera- posure tions Limited studies of workers involved in brake servicing have suggested that their related exposures may be associated with asbestos diseases.,, NIOSH estimates that a work force of 151,000 brake mechanics and garage workers in the U.S. is potentially exposed to asbestos Potential exposures are a result of 125 million pounds of asbestos used annually in the U.S. for the production of brake friction materials Besides asbestos other materials e.g. binders friction modifiers fillers are used in the manu- facture of brake linings that can likewise have a potential for exposure As noted in one study 30 materials and compounds that make up the binders fiber reinforcers property modifiers etc. were identified during brake lining manufacturing 5 198 198 a ei { i i * BRAKE MATERIALS PRODUCTS AND USACE Historical Development of Friction Products Products of early automobile friction materials were relatively The requirements minimal Passenger cars were light and Brakes were of an external contracting designed type and for low speed operations utilized a variety of mate- rials this included leather and impregnated cotton products which were used along with wool commonly materials were first marketed and felt In 1903 woven in the United States by asbestos friction the Keasbey and Pennsylvania Mattison Company of Ambler Because of their superior heat resistance and durability they rapidly increased in use and soon dominated brakes continued to be the dominant product the market The woven asbestos used in automobiles cored asbestos until about 1930. They typically contained yarn impregnated with drying oils such as 70 or more linseed and bituminous material Molded brake linings were developed in the early 1920's and gained increas- ing use with the introduction of internal tually all automobiles were equipped with shoe brakes in 1927. By 1940 vir- molded brake linings although be used in trucks heavy equipment and for spewoven products continue to The molded linings in use were cut to length usu- cialized applications and mounted on brake shoes using rivets Until ally by the manufacturer the mid 1920's brakes were only mounted on rear wheels however with the development of internal shoes four wheel mountings soon became standard As automobiles were designed for use at proved in both quality and performance duced as fillers binders and friction higher speeds brake linings in- Various new materials were intro- modifiers In 194 bonded brake ee 6 ee oe developed and soon accounted for approximately 40 of the orig- linings were In addition they rapidly dominated the reinal equipment brake market of the considerable savings in labor during instal- market because placement disc brakes were introduced on American autoso- lation In 1965 the first biles and rapidly increased in use In 1975 virtually all original equipment front wheel brakes of this type However because of less stringent cars had and the difficulty of braking requirements brakes to the disc configuration the rear adapting mechanical wheel brakes on 95 parking of currently sold cars are still of the drum variety for Brake Linings Requirements coefficient of friction CF A constant or slightly decreasing perature up to values of from about 1000 F 0.30 to 0.45 is required for an efficient brake are normally sought Lower values with tem- lining CF produce brakes requiring too sensitive to excess pedal pressure and and those with higher values are pressure develop excess wear Ideally the desired be maintained throughout the life of the lining frictional qualities should chemical and physical physical changes occur in the material During braking braking These changes may produce an increase material at the surfaces fade in friction Satisfactory linings will fade build or a decrease but will return to their initial state slightly upon repeated applications upon cooling A is obviously desirable for economical and practical Lov wear of the linings be associated with the However high wear resistance can considerations reduction in the CF. of the lining to glaze with a concomitant tendency of the brake lining mate- This can be overcome by allowing a slow alteration 4 CRED _ aes earmes ae can scams SR _ eee ames me me ee ee -1 rial to occur Pyrolysis of the organic binders and thermal decomposition of the chrysotile fibers under braking provide the necessary continuing renewal ofthe lining surface The lining should be abrasive to the drum surface In addition to causing rapid drum wear abrasive linings score the drums which in turn leads to a rapid wearing of the lining Drums made of cast iron and steel are common with steel being more susceptible to scoring Since brake drums have a hardness of from 3.5 to 4.0 on the MOH mineral hardness range of 1 to 15 in which tale is rated 1 and diamond 15 scale virtually all lining materials used have lower hardness values Other necessary or desirable properties of brake linings include physical strength dimensional stability quiet operation and safe and offensive degradation products Of the various properties desired in the lin- ings greatest attention is paid to build and recovery characteristics hear problems are not as serious and can more readily be overcome with the materials available Compounding Ingredients of Brake Lining 7,8,9,10 To achieve the desired friction properties a wide variety of ingredients are commonly used in the manufacturer of automobile brake linings These include Asbestos Asbestos is used for fiber reinforcement of the friction product Chryse- Chryse- tile is used almost exclusively and comprises from 40 to 50 percent of the . ee oo ee oe ee es brake lining _ _ _ Fiber grades 4 through 7 are used and occasionally several sizes are mixed or even calcined to improve performance characteristics Amosite crocidolite or other amphibole asbestos varieties are not used because they are too harsh and tend to score the brake drums Organic binders Organic binders are primarily phenolic type resins selected for high binding strength Unmodified phenolic resins when subjected to heat usually become hard and brittle To prevent this linseed cashew nut or China wood oils or cresols are added Rubber which also finds use as a binder imparts desirable friction qualities and improves the flexibility of the lining material Friction modifiers Friction modifiers are added to achieve a desirable CF over all operating conditions These modifiers also produce a more homogeneous lining surface Included among these materials are lead zine brass cashew nut oil graphite and oxides of iron and copper Fillers Fillers such as rubber scrap barites clays silica coke coal and other minerals are used These also have utility in achieving desired friction properties in some cases through action as abrasives to recondition braking surfaces One major major purpose of the reconditioning agents is to retard the formatioonf forsterite which may accumulate on the surface of the brake lining Forsterite is < mineral not originally present in the brake terial but is created by dehydroxylation and recrystallization of chrysotile asbestos at high temperatures The hardness of forsterite 6.5-7.0 < ow eee re r eremeetmnes ae ee eee + es ee eee o-w-e on the MOH Scale is such that it tends to score and gouge brake drums and prematurely Therefore recrystalli- discs hardness 3.5 degrading them prematurely forsterite is is an unwanted effect zation of chrysotile to Curing agents Curing agents cal reactions and accelerators are used occur to produce the desired to assure that brake quality appropriate chemi- Types of Brake In the making processes are Linings and of different utilized to Manufacturing Processes types of brake linings achieve a wide range of various manufacturing potential applications These include Wired Back These are made by a into a ribbon about calendering process a wire backing The in which purty stock is formed wire reinforcing serves to maintain Furthermore as linings of this type strength during the curing process reinforcing reinforcing provides long term structural are invariably riveted the wire shearing of the strength and prevents were extensively Linings of this type lining at the rivets during produced prior to borld War braking II They are in little use today Extruded Linings These are manufactured by extruding extruding priately sized rectangular orifice lining curing agents are added to the soft plastic stock through an approTo minimize structural weakness in this a hard inflexible finished proproduce ducts Sheet Linings These are laminated structures formed by winding a 0.001-0.002 inch film of stock about a hot roller Since the fabrication process is a relatively expensive one linings of this type are not commonly produced for general use Dry Mixed Types This process involves the dry mixing of various ingredients capable of pass- ing a 200 mesh screen and then molding the lining under pressures of from 1000 to 3000 pounds per square inch The resulting lining is among the most heat stable of friction materials in use today and obtains wide use in the manufacture of brake blocks for heavy duty service Millboard Type The manufacture of this type of brake lining material is by a process simi- lar tothat utilized in the paper industry Wet stock is formed and passed over rollers with various drying and baking operations producing sheets of uniform lining material The equipment for producing such materials is but the volume of production leads to an economically produced expensive molded lining LINING AND MAINTENAS -E PRACTICES HISTORY BRAKE BRAKE concentrations of brake lining materials has led large extent changing character To a To materials has led practices differing asbestos lining to changing changing practices when braking was done exposures exposures over the years From From 1920 until 1930 materials the predoginant use exter- exter- nal nal brake bands from woven from the cutting and fitting of the exposure to bestos would come bestos were lining Most likely the airborne fiber concentrations considerably material of considerably developed in later years when less less those was comon developed using gpolded l.nings, internal brake shoes were From 1927 when all internal brake were introduced until 1945 when bonded brake linings rivets The lining material for use using were attached to shoes Linzngs size various various would be precut to appropriate market in the replacement from rolls of indeterminate length precut precut segments would oF obtained shoes shoes the factory for rapid mounting In usually be predrilled at would for rivets rivets bevelling bevelling however drilling be done circumstances, them The of rolled rolled linings required cutting cutting the the mechanic installing rivets and bev- bev- material to shape drilling holes appropriately elling the asbestos Under latter latter circumstances exposure to workers appropriately when shoes with predrilled predrilled bevelled linings could be considerable bevelled the the installed processes processes punching punching were linings rivets the greater greater exposures exposures shoes than to greater exposures would give rise rise and riveting on the new shoes use of bonded linings linings that accompanying grinding grinding grinding during installation lining, operations during installation operations need for drilling facing or OF However decreased significantly the 1950's when automobile shoes were for a short period of time in first installed with a fixed anchor some tapering was necessary on uniform to achieve a proper fit Previously the end of thickness bonded linings that of the hydraulic cylinder could be mechanically the shoe opposite to adjusted Shortly thereafter tapered bonded linings were available from 1900 the factory Subsequent to considerably fewer bevelling or grinding 05 ate-. automobile mechanic replacing brake lin- = e performed by an du,-- of internal shoe brakes common practice was to remove During replacement the brake wear dust from the housing by air blowing or brushing After 1970 in brake- of the hazards of asbestos and its presence increasing awareness lining dust led to wet work practices in some brushing wet wiping dry brushing or vacuuming facilities However even today such brake servicing are not universal improved work practices automobile shops were relatively small and In the 1930's and 1940's most all automobile maintenance and repair activities zost mechanics performed increasing however there has been an In recent years tendency towards with shops existing for brakes and front end work exclu- specialization during brake work on an individual sively Here while asbestos exposures workers are exposed for be less than those of previous years some job may considerably longer periods of time x -~ __ SELECTION OF FACILITIES SURVEYED _ of the industrial hygiene study was to investigate and charThe purpose resulting from vehicle brake maintenacterize contemporary dust exposures operations ance and repair taking into account the work practices utilized Therefore it was necessary to were used servicing techniques locate facilities where a variety of brake as well as where there were differences in Two of the six sites selected for the the number of vehicles serviced automobile brake service facilities which performed up investigation were week at an average of 65 minutes per vehicle The reto 45 brake jobs per maining four facilities serviced both autos and trucks and performed from week The service time varied depending on the 5 to 45 brake jobs per were conducted at of vehicle Detailed airborne dust sampling surveys type each facility DESCRIPTION OF BRAKE SERVICING OPERATIONS found at each facility were basically as follows The servicing procedures stall or bay for a brake system examThe vehicle is driven into a repair nation Pending repairs the wheels are elevated removed and then inspect- ed Loose dust is cleaned from the drums and vet or dry brushing using compressed methods Parts are then replaced or repaired brake assemblies by vacuuming air or a combination of these as needed and the brake system is reassembled and adjusted and adjustment is the final scription of the individual Test driving the vehicle for proper fitting of the servicing operation A brief phase is outlined in Appendix . facilities de- 10 SAMPLE COLLECTION AND ANALYSIS METHODS 1 Airborne Samples periodically collected at each facility on dif- Personal and general air samples were year period Brake servicing operations and ferent occasions during a immediate vicinity of brake work within each facility were areas not in the data Personal air samples monitored to provide overall asbestos exposure of the brake mechanics using plastic vere collected in the breathing zone Type A4 37 millimeter mm diameter 0.5 cassettes containing Millipore membrane filters The samples were operated at micrometer um pore size minute Lpm The filters flow rate of 2.0 Liters per a calibrated sampling during the work shift to prevent particulate over- were changed weighted average TWA fiber concentrations loading on the filter brake service and peak conwere determined for the time spent performing brake dust from drums determined for time spent cleaning centrations were were collected using and assemblies Samples for personal peak exposures media as above identical at about 11.0 1pm using Cast pumps calibrated train was used for peak sam- At facilities C D and E a 2.0 Lpn sampling for asbestos fibers were con- All analyses of the membrane filters Occu- ples outlined by the in accordance with the procedures ducted by the auther and the NIOSH Manual of Analyti- Administration pational Safety and Health 230 cal Methods CAM These than 5 ...min length and procedures require the with at least a 3 to 1 counting of fibers length to width greater aspect ratio of 400-450X contrast optical microscopy at a utilizing phase expressed as fibers per cubic Concentrations are magnification centimeter of air fibers 11 / facility surveyed as well as those samples Random samples from each high were fiber concentrations as determined analyzed on a transmission electron by the optical counting methou microscope TEM utilizing selected identification SAED and energy dispersive ray analysis area electron diffraction with fibers 2 3 EDXRA Samples were observed at 17,000X magnification SAED was attempted on all obratio sized by length and diameter aspect In addition EDXRA was performed on in- served fibers for their elemental composition SAED patterns dividual fibers to determine were compared with reference minerals elemental spectrum ratios and EDXRA Institution obtained from the U.S. Smithsonian chrysotile and forsterite and analysis were performed using the method described Sample preparation Review and Evaluation of Analytical Methods for in the Technical Report 13 13 Environmental Studies of Fibrous Particulate Exposure General arca samples for trace were collected at most ganese volume samplers at a flow rate a sampling train and flow rate metals lead zinc copper iron and man facilities using Staplex Type TF high- minute and also with of 10 cubic feet per like that used for asbestos fiber collection Samples were analyzed for metals by atomic with the NIOSH methods CAM in accordance absorption spectrophotometry Number 222 5156 5341 and 14,15 Bull Samples . Samples of brake wear dust were collected vehicles that were being serviced during and analyzed by TEM for characterization from the brake drums of several the surveys These samples were identification of fibrous partic of fiber size distributions ulates and for determination wee woes ecssemert 12 WORK PRACTICE CHARACTERIZATION During the surveys considerable emphasis was placed on detailing work procedures during brake servicing in order to document the types of cleaning practices e.g. vacuum compressed air brushing used in replacing brakes As previously described in the section Description of Brake Servicing Operations the brake servicing work practices utilized were similar for all facilities surveyed the major difference observed was the methodology utilized for clean of brake wear dust from the backing assemblies There were six different types of clean methods observed during the study Those six methods are described as follows 1. Compressed Air Blow A compressed air stream was used to blow away brake year dust from the brake assemblies and drums 2. Compressed Steddard Solvent Mist Blow The same as # ex- cept a spray gun containing stoddard solvent was used to produce a solvent mist for blow 3. Dry Brushing Brake wear dust was brushed away with a small utility brush usually 1 inch in diameter 4. Wet Brushing Basically the same as dry brushing except the brush was kept saturated with a liquid such as gasoline water or ~ stoddard solvent ee ee 13 A liquid bottle containing water was used to 5. Squirt wash away brake dust This was followed by drying off assemblies with a cloth vacuum cleaner equipped with a HEPA Vacuum Cleaning A shop type filter included used in combination with compressed air This system was brake encapsulation cylinder that completely enclosed a the backing plate assembly The mechanic operated a com- pressed air dust which nozzle fixed inside the enclosure to blow off drawn was immediately into the vacuum system the brake A sepa rate vacuum hose was used to vacuum the dust from the brake drums Particulate Air Filter -99.7 -99.7 efficiency HEPA High Efficiency for 0.3 ...mdiameter aerosols 1 to 3. the brake dust has the In Methods 1 to 5. and especially potential in Method air of the facility Conversely to enter the ambient 6 the dust is contained by the HEPA filter which may be removed from the vacuum cleaning system for disposal 14 SURVEY RESULTS ANC DISCUSSIONS Asbestos sure Levels Asbestos The and fiber The microscopy background background samples for the TWA, peak personal, count analysis TWA personal in count analysis for the summarized background background concentrations col ected during study the Tapdle Table to 0.28 fibers cc while ranged from to 15.00 from fiber peak peak levels cc The and peak tended to fluctuate. exposures mechanics exposures fluctuate perhaps best explained utilised, variations in practices by variations inconsistencies inconsistencies in performing throughout the brake work existed brake , and because and therefore repair off is intermittently clean represents represents small percent percent during the shift For of of the performed the amount time number of brake jobs brakes and the spent servicing there performed performed likewise among the mechanics differences differences shift differed per brush yacuua), methods e.g. compressed air procedural procedural adda- in cleaning breathing breathing from brake housing e.g. distance tion brake brake drums on the addi- who dropped mechanics were some at each =~ causing there Environmental conditions dispersal of brake dust and open brake airborne ventilation controls facility such shop shop size and back- windows and exposure exposure doors would also affect individual ground concentrations fibers of airborne asbestos Regardless cleaning mechanics mechanics exposures exposures method utilized facilities facilities cleaning not not ret facilities 0.1 fibers and consistently than differ differ from fiber samples collected collected in tre mechanics general general work area concentrations TWA exposures exposures The similarities mechanic concentrations concentrations background fiber individuals individuals in the all that fiber concentraticns and background es we . ace 13 exposed to the same fiber con- work environment are potentially immediat the further sup- potentially potentially exposed a environment environment centrations centrations observation further further of the that normal work shift This much of ported ported ported mechanics mechanics mechanics monitored from the several of the the work shift of the shift at site but spent those those that TEM TEM Characterization electron gsicroscopy ( TEM} selected selected transmission Samples Samples randomly microscopy microscopy TEM and 10 electron fibers sized length length diameter for with with fields analyzed fiber concentrations eeach sample sample addition were determined determined in length These fibers fibers > um con- for for fibers eethod concentrations concentrations were the optical microscopy pared to those found found ef reportedreported reported in the concentrations Table 2. 2. In but three samples um in slightly higher were determined by optical microscopy the result of those fac- determined was probably tors bY TEM This difference for TEM, sample preparation less during These include particulate ig net TEM asbestos while this selectivity fibers sre counted by TEM actually eountes with and the small number fibers fibers on each micrescepy, the number of of differences counts small At low fiber fibers counted on on the fibers method a significant significant calculated calculated result each microscopy of Statistical comparison optical of the fiber concentration because TEM not attempted because counting methods the disparity disparity picroscoPy determining determining of the two methods Besides for fibers capabilities were the concentrations concentrations fibers observed were concentrations concentrations calculated >Sve length total greatest greatest counted AS be expected the shorter proportion of observed length 80 91 . Qo"). um length observed was shorter cau os fibers pecpoe 1? Table 2 _ Comparison Air Sample Air Sample Results 2 Fibers Sample Results Fibers Analyses O\p~tical0.Opti5cal 8 0757 1.43 fi Elecctse Micraszo0y Tranmarssion Micros 7 Fibers Microspy Microscopy TO Transmission Transmion Transmission Electron Micros Micros Micros " length Microspy Microscopy um | Total {~">5 > um length fibers { Fibers \ \ in Sibers | { 0.25 | $3 0.50 | | 0.56 | 0.25 | | 50 11.33 6.9 | \ 5.97 | 1.01 | 3 \ \ \ 2.35 | 17 j 1.18 | 0.10 | 29 0.76 \ { 0.13 | 0.07 | 14 | 0.43 \ 83 6.86 | | 0.33 0.39 | \ 5.39 | 0.02 i] \ 0.02 0 0.82 | | 0.0 \ 9 0.11 | \ 0.01 | 0.0 | 16 0.0 | \ 0.01 \ 0.19 | 14 2.72 \ | 0.02 { 0.16 | 0.48 | fe] 0.38 | ) { | 0.0 0.08 | | 1. 0.01 \ 0.0 \ \ 100 0.26 | | 0.09 | 23 0.09 \ 0.26 \ \ Q | 0.00 0.16 \ | 0.06 | 0.0 | 100 0.01 | 0.12 \ *) | 0.01 \ 0.01 \ 0.03 \ ) | \ 0.0 0.0 \ \ 0.03 \ 0.0 \ ) . \ 0.0 \ | 0.0 \ 68 .86 | \ 0.12 Blank \ 0.42 \ $0 0.20 \ 0.17 | \ 0.10 \ 33 0.43 | .18 | \ 0.16 \ 33 0.15 \ 0.06 | \ 0.05 | 68 0.73 | | 00..1122 \ 0.50 \| . \ \ counted fibers only asbestos | counted Sy TEM represent eNote: Ficers k i) | | | | | | \ \ \ \ { a 18 Fibers observed by imately 50 of the TEM were identified utilizing fibers analyzed by SAED could SAED and EDXRA Approxnot be identified due to ambiguous diffraction patterns as chrysotile and approximately About 30 of the fibers were identified 20 as forsterite The presence of fibrous due to the dehydroxylation dehydroxylation and recrystallization forsterite was probably result of high temperatures > 650 C encountered during of chrysotile asa 1,2 Some of the fibers which revealed ambiguous diffraction patterns braking structures similar to both chrysotile and forappeared to have crystalline intermediate sterite probably a transition while others were too small for diffraction analysis EPARA was performed on the fibers to confirm the SAED analysis that was made for the chrysotile and forsterite fibers Some of those fibers which gave ambiguous SAED patterns indicated magnesium silicon and iron in various elemental ratios typical of asbestiform miner- als when a fiber size distribution was performed for all As shown in Table 3 airborne um and a sample fibers observed by TEM a geometric mean length of 1.00 mean diameter of 0.14 um were determined Likewise for geometric asbestos chrysotile a geometric mean length these fibers identified as and diameter of 1.70 um and 0.15m 0.15m respectively were determined dust were analyzed by TEM in the same manner Bulk samples of brake wear Identification was attempted on all fibers using as the airborne samples SAED and EDXRA Approximately 70 of the fibers analyzed by SAED could not EDXRA or the absence of diffraction patterns be identified due to ambiguous observed with elemental analysis being success- was performed on all fibers 19 -o0a9 a2q id 60 T O ? cert PIS yiduay *oa9 ureH | out 997% 070 Brake Diametr 08-920 Fiber Oo [9f1T 32qtd aVucy Ot-9720 -709 t.co. 0.15 9 eiaqts ust a7s 601 ) 30 0.14 Bulk eAO CT ) cuz an 0.06 0.18 | esl 4 Chysotile PIS Aq ( < Al Dust pauyersip FiWVL NG oO.) UE 410 1-U oro g00 astveig detrmined determined LIA 49454_ aguty 238 yepaog gto-90O 6z0-90 01-90 o*t-90 29q1) pavueds1tV saqunygo29q54 . 1st e C74 601 we 3 t 2730649) WIkL baptdurs(Ae2qauqpyg sa[dergquaeqnd J2eyvnsgg(X82qu91o4 a2eqenagg (ws0qT8 S1AnVS 2us0Qgty 217 suoqary Ttv) NINE HITE TTY) 20e4) 20 positively When utilizing SAED and or EDNRA several ful on about 70 of the fibers identified as chrysotile 105 while of the fibers observ i were -20 or unknown 70 Many of the were either forsterite the remaining thought to be intermediate recrystallized forms between chrys- unknowns were In addition a fiber size distribution was performed otile and forsterite vs. 0.24-10 um and shorter lengths 0.24-5.9 um which indicated someshat 0.06-1.0 um than those observed in smaller diameters 0.06 0.29um vs. the airborne samples in Table 3 Trace Metal Analyses following detectable airborne samples collected at metal analyses were performed on Trace and E with the results reported in Table 4. Samples Facilities B C D and man- metals lead iron zinc copper were analyzed for the 0.0 ug and limits of detection of 5.0 ug 1.0 up with analytical ganese As noted in Table 4 the metals were often 1.0 ug per sample respectively B had a and only facility ND or found in trace amounts Pb that exceeded OSHA or metal concentration bgm for all facilities The range of concentrations m m In ND - 352 Cu m Fe ND - 2,300 NIOSH exposure were Pb NP > ND - 5.7 standards 03.3 and Mr. ND 3.5 g... . 21 _ ve 0 ono s00 90 0 - - - aq a aw jaieS*= <0O 700 700 S zo Table co - Table ") "aN Metal Metal Analyse u/ pao atdwes 234 I (4a) of Trace Metal N.D. 351 /ou0'S Fe ou0$ N.D. - - N.D. S$ N.D. N.D. o l9 0o'l 349 1,80 < 0 0.3 0.1 - 0.6 1,50 0.5 paucwm0 jado) aucduy 1,50 0.2 ) 19.5 | 294 0.3 J - 0.2 DeIZ | - 8.7 1,20 HSOIN 0.3 1,700 2,300 oue t or ! 0.2 - 7- OSHA_Exponure OSHA_Exponure Standard avi atucya4 g NIOSH Recomende Recomende 5,00 I c'c9 Iron 6 9t 5.0 - Coper ~ - os oul eyteuy e1eqH r 44 aN Manganese Manganes ug 44 aung awng poe p2 9240d Spro oP 0 020 0 yon YOIE 2jIZ gado}Sut{29 -=--- e i] a a oe arypedpatains 22 ve an vev seve POTENTIAL HEALTH EFFECTS FROM ASBESTOS EXPOSURE for the inhalation of chrysotile as- The human toxicological significance bestos fibers is well documented and instances of mesothelioma in auto 16,17,15 repair workers have been identified In a detailed examination of City workers in New York 90 union vehicular maintenance with 10 or more years of shop work 29 decreased vital capability the percentage in- markedly after 20 years from the outset of auto creased with age and most examined showed signs consistent with asbestosis work Many of the workers noted in chest rays and indication of restrictive with observed changes function The prevalence of these changes was significantly higher > pulmonary result expected after occupational exposure to after 20 years exposure a 10 asbestos Unlike chrysotile the health effects of exposure to forsterite or transi- tion series fibers tures are not well chrysotile forsterite with altered crystalline struc- Coniam documented In studies by Davis and and and forster- Koshi in which fibers of chrysotile chrysotile into the pleural and peritoneal cavities of mice the ite were injected of toxic effects Fiber implantation aniresults suggested varying degrees conducted mal studies 22,23 by Pott et and Davis et al suggest of a fiber regardless of fiber type are rethat the morphology and size sponsible for its carcinogenicity Likewise in diameter and 6 um in that fibers 1.5 um Stanton et al suggests length pose the greatest risk These studies tend to suggest that the phy- in producing pleural sarcomas and to a lesser degree chemical and sur- sical morphology size dimensions the determining factors for inducing face characteristics of a fiber are 23 precise fiber dimensional characteristics required a biological effect The have been difficult to determine observed pathologic responses for these fibers of the difficulties encountered in producing experimentally because of specific size dimensions w 1 26 et SUMMAR: The The airborne asbestos sample results for all facilities were within sample the the current asbestos for sasples collected at Facality two of four sample results However However samples samples collected Facility during compressed air for B Table Table during assemblies assemblies exceeded The compressed air brake the the ceiling standard method also indi- (up to 15 cleaning overall peak exposures cated cated highest methods examined compared the KI0SH recomended results are compared to when when overall TWA sample for recommended recommended 5 of 13 of the TWA exposures standard for asbestos The NIOSH mechanics indicated recommendation concentrations exceeding the with a recommends of 0.1 fibers 5 cc fibers an E TWA exposure Peak ceiling sampling period fibers for any 15 minute thes of 0.5 exposure the NIOSH standard since directly the results could not be not collected over minute periods were utilized CV_ their co- coo collected yielded low fiber counts that efficient efficient the samples considered considered reliable (i-- was above is greater of variation are best best concentration Consequently Consequently fiber concentration for comparing cleaning different different variations the methods work practices exposure pethods/work practices. 25 CONCLUSION _ ?? indicate varying concentrations studies results of this and The The concentrations to brake indicate indicate varying asbestos exposure of asbestos The exposure concentrations concentrations affected affected the work mechanics are apparently and existing existing this conditions controls at practices utilized environmental conditions facility facility results of this pechanics each study study show that 8 of 13 of service service TWa brake above NIOSH recommendation above fiber exposures when However all exposures exposures were below the standard Furthermore analyzed analyzed the were observed were when as TEM TEM only % of fibers (207) or asbestos the as forsterite being categorized remaining fibers unknowns the levels of the asbestos result the TEM analysis As a result Bay be less concentrations these determined by optical microscopy (>5 -2 length as the than this does not preclude reported see Table 2 However all fiber sase ranses when asbestos fiber concentrations of higher airborne analysis this this study and ranges As determined by the TEM are considered number to 100 of of short a significant studies other reported Table and research research usually present see 25 (<5 ein length are exists asbestos asbestos fibers health risk that & potential 25 5um indicated the unknown unknown health may exist for fibrous fibrous portion Also, & potential animal studies studies which which results fibrous 50 of brake dust results = various size 22,23,24,30 2,23,24,30 concluded that were implanted animals animals physical physical morphology (sise dimensions to and surface characteristics of a fiber the determining ducing biological effect lesser lesser degree chemical determining for chemical in- in- ducing & biological effect- chanics who performed chanics, whe perforned brake this study were only drake maintenance me- ae- full brake may have serviced serviced and 26 who undertock aS few as per days a week, oF mechanics up to cars up week or mechanics mechanics undertook undertook few per Regardless one one brake job number number brake jobs performed performed ) the fibder exposures (per per shift mechan- mechan- tO mechanics exposures similar for ics surveyed surveyed exposures performed full time brake brake higher than the exposures significantly were were for those did such Conversely the shert ters less less servicing minutes minutes peak expo- encountered this study during the dust sures encountered aif was clean off of braking assem blies often higher when compressed blies fiber cleaning for vacuum cleaning had peak methods surveyed except concentrations concentrations ceiling exposure recommended that that near 0.5 fibers near above the the compressed air cleaning eethed However even exceeded the and in two cases was level of OSHA only approached type which limit of exposure mechanics are at ing the cleaning strongly indicate that brake 10 fibers cc These findings @ higher of brake asbestos asbestos fiber: brake risk of airborne exposure the vacuum cleaning methassemblies except when ods are properly utilized were within within collected for trace metals had concentrations The samples area sample sample standards all all one case One collected collected at NIOSH exposure which which B indicated lead lead concentration 63.3 ug exceeded the standard NIOSH recommended recommended was below below m standard of ug standard of ug standard of 100 n 27 Senet performing ics performing titled Recommended (see Appendix Appendix C KIOSH has and elutch maintenance clutch maintenance maintenance NIOSH has Recomended -acedures utalized for Asbestos Brake and and 6: prepared guidelines prepared guidelines Clutch Servicing oo. | 29 -2 eo APPEXDIN A _ APPENDIX Nicholson, -J-, and Miller, A-, and the W.J. Lorimer Lorimer Rohl a.N.,Miller Miller A. Nicholson Selikoff Selikoff RI.o J. h Asbl estos Exposure Exposure Brake borkers United States May States and Human U.S. Dept. of Health Hazard Survey. Health Human Dept. National Occupational Survey Dept. Public Occupational Hazard Disease and Human Services Occupational Service Centers for Institute Institute Research Institute 1976 Cheaical estimate April Stanford October 1977 712.1000C of fricition on the development Much of historical information the development development of fricition 4. obtained from information William William Nicholson products products School School Medicine interviews by , Friction JF-, Mount Sinai Paramus Edward Drisane Materials Standards Institute Paramus Molded Materials Co. Ridgway catalog 1920. Aabler, Pa. Keasbey and Mattison products 1903). Automobile Brakes Fleet Owner (August Friction Materials on of Brake Linings British Plastics 414-417 W.G. The Manufacture 414-417 August 1902 Ford Motor Co. Detroit MI. A.E and R. Gealer unpublished unpublished notes at che An Introduction Brakes Brakes Inspection Inspection Station Brake DynamicsVeh Resh N.H. N.H. Brakes the 403-472 Level Motor CChhaaptpetretrl, 403-472 1908 Exposure During Brake Lining 11. U.S. A-N- @fi al Asbestos U.S. Title part 1910.1001 1910.1001 Department Department of Labor Occupational Safety Health Health Administration li. Safety Safety Occupational OTccaupy atilono al r Safety and Health Standards Edition Edition Publications Analytical Analytical Methods No. Publications 77-157 77-157 12. Volume CAM Ko. 239 Publications Zumwalde , P&CaM of and Evaluation Evaluation Environmental Studies Particulate Fibrous Particulate 13. Analytical Methods for Environmental Publication Studies Exposures DHEW NIOSH Publication 77-204 77-204 DHE (NIOSH) Taylor Publication Publication Analytical Analytical 2nd Edition Edition : 77-157 57eA- CAM 222 77-157 14. Volume ho. 222, Publication Tavlor D.G 1977 Analytical 2nd Edition Edition 5150 341 Publication Publication No. 77-157 C 16. VVoolluuexmee 111, Sito, MI, 306 Publication Aol sort 0 + SET B40 o 16. 17. Newhouse Following M.L. and and Exposure Exposure Thompson H. Mesothelioma Mesothelioma to Asbestos in the the London of Pleura and Peritoneum Area Brit J. Ind Med 261-269 1905 McDonald Tumors in A.D. et Canada . al Epidemiology of Primary Cancer 914-19 1970 Malignant Malignant Mesothelial M. and Lloyd Davies T.A. Mesothelioma Register 18. G1r9e67e-n1b9e6r5g Brit J. Ind Med 91-104 91-104 1974 19. Bader M.E. Bader R.A. Teirstein A.S. Miller A. and Function and Radiographic Changes in 508 Selikoff 1.J. Pulmonary Pulmonary to Asbestos Mount Sinai Workers with Varying Duration Duration of Exposure J. of Med 492-500 492-500 1970 20. J.M.S. and Conias S.W. Experimental Davis and Automobile of Heated Chrysotile Chrysotile Asbestos into the Body Cavities of Mice Experimental Volume 19 pp 39-353 339-353 1973 Studies on the Effects Brake Lining Dust Injected and Molecular Pathology 21. Koshi K. Hayashi H. and Sakabe H. Minerals Minerals in Heat Studies on Serpentine Volume 7 pp 60-8 1900 Biological and Treated State Mineralogical Ind Health 22. 22. K.H. Tumorigenic Effect of Fibrous Pott F. Muth F. and Friedricks Health Perspectives Dust in Experimental Animals Environmental Volume 9 pp 313-315 313-315 1974 23. F. Huth F. and Friedricks K.H. Tumorigenic Effect of Fibrous Carcinogenic Effec of Fibrous Dusts Pott Concerning Concerning the Carcinogenic Experiments the Ca. .nogenesis in Humans Interpretation of of RePsautlhtosloCgoinqsuiederPariisnPagris 1970 Volume 21 pp 237-240 Annales d'Anatomic d'Anatomic 24. Effects Effects of Mineral Dusts Injected .M.C The The Fibrogenic Journal Exp Pathology Davis the Pleural Cavity Cavity of Mice British Volume 53 pp 190-201 190-201 1972 inte Stanton M.F. Layard M. Tegeris A. Kent E. The Carcinogenicity of of Fibrous the Rat in Relation to Fiber Dimension 58 587-603 March 1977 Miller E. May M. and Class Pleural Response in J. Natl Cancer Institute Title 29 part 1910 U.S. Code of Federal Regulations Section 1910.1001 July 1970 Zumvalde R.D. and Busch K.A. NIOSH N.A. Bayer S.C. Filter Method for Evaluating @. Leidel NIOSH Membrane Technical Report DHEW NIOSH NIOSH Publication No. 79-127 Airborne Asbestos Fibers February 1970 ~ Aeemn omens + 28. S.C. Zumwalde R.D. and Brown T.A. Equipment and Procedures Bayer Filters and Counting Asbestos Fibers by Phase for Mounting Millipore of Health and Contrast Microscopy Available from U.S. Department Human Services National Institute for Occupational Safety and Health 29. Gillam J.D. Dement J.M. Lemen R.A. Wagoner J.K. Archer V.E. and Blejer H.P. Mortality Patterns Among Hard Rock Mineral Annuals of the New Gold Miners Exposed to an Asbestiform York Academy of Sciences 330-344 1976 Blackwell R. and Miller E. Experimental Pulmonary Stanton M.F. Ind Hyg Assoc J. 230-241 Carcinogenesis with Asbestos Am 1969 31. of Health and Human Services Public Health Service U.S. Department of Health Asbestos An Information Resource National Institutes DHHS Publication Number NIH 79-101 May 1975 - APPENDIX B Description of Facilities Surveyed Facility A an automobile brake service shop consisted Major services at Facility A shock absorber servicing and brake maintenance of front alignment was made up of five hour days and one hour day The normal work week a Facility B Facility B was Other services the largest provided by of the automobile brake service shops surveyed this facility were front alignment and shock The five time mechanics worked from absorber replacement or repair four service stalls O hours per day 6 days per week Brake maintenance consisted of 35 to 45 jobs per week operations Facility C At Facility C vere performed the 60 auto an average of eight brake jobs per day a municipal garage and trucks Brake maintenance was performed by any on cars were & hours per day 5 mechanics The hours of operation days per week 3-1 eee oe ame Facility D there was an average of one complete At Facility D a sunicipal garage brake service job per day taking about 5 hours per job with most of the vehicles consisting of cars or light trucks There were five employees re- sponsible for brake servicing and the facility operated 8 hours per day : 5 days per week Facility E three Facility E a municipal service garage employed mechanics that specialized in brake and clutch service and three emplerees operated shop specializing in brake shoe and drum recondi- a separate brake repair tioning The brake mechanics serviced all vehicles which included baste trucks collection dump and light autos and some 2- and wheeled vehicles The shop operated s hours per day 5 days per week ai Facility F fleet service garage performed complete automotive Facility F a private and light truck maintenance The shop normally operated the shafts 5 days ky. per week and there were usually four time mechanics per shift About one brake job week per shift was performed - APPENDIX C RECOMMENDED PROCEDURES FOR ASBESTOS BRAKE AND CLUTCH SERVICING The National Institute for Occupational Safety and Health NIOSH has conducted research on dust exposures which are generated during brake and clutch servicing Based on data demonstrating the potential for significant asbestos exposures during brake and clutch servicing NIOSH has investi- gated various work practices which are utilized in reducing asbestos exposures These investigations have indicated vacuum cleaning systems to be the most effective method for minimizing asbestos dust exposures during servicing brake and clutch 1 Vacuum cleaner testing have demonstrated the these units operate reliably within design specifications Therefore NIOSH recommends vacuum cleaning as the primary method to be used for clean- ing of asbestos dust during brake and clutch servicing operations The following are additional procedures recommended by NIOSH to minimize asbestes dust exposures 1. Where possible an area shall be designated for brake and clutch re- pairs and servicing Entrances into this area shall be posted with the following asbestos exposure warning sign printed in letters of suffi- cient size and contrast to be readily visible and legible Asbestos Dust Hazard Avoid Breathing Dust Year Assigned Protective Equipment C _ eee Do Not Remain in Area Unless Your Work Requires It Breathing Asbestos Dust May Be Hazardous to Your Health 2. Dust shall first be cleaned from brake drums brake backing plates brake assemblies and clutch assemblies using an industrial type vacuum cleaner equipped with a high efficiency particulate air filter system than 99 efficiency for 0.3 um diameter aerosols After greater vacuum cleaning any remaining dust shall be removed using a water dam- or Under no circumstances shall compressed air pened rag dry brush be used for cleaning If vacuum cleaning equipment is or a not available the wet brush cleaning method may be used until a vacuum cleaning system is obtained Where et brushing is necessary for clean- ing a NIOSH certified respirator approved for asbestos shall be worn riveting and punching operations local ex3. During brake pad grinding shall be designed in- haust ventilation and dust collection systems the American National Stand- stalled and maintained in accordance with ard Fundamentals Governing the Design and Operation of Local Exhaust ANSI 29.2 - 1977 to meet the asbestos airborne exposure standSystems ard NIOSH certified respirator approved for as4. During clutch servicing a . the removal and cleaning of the clutch bestos shall be worn during assembly and during installation of the pressure plate and housing Whenever possible cleaning shall be performed new clutch assembly as described in 2 above with an HEPA vacuum system 2 ED ee _ _ o - : fe machines where brakes and clutches are 5. 5. All table and cleaning in areas clutches are repaired shall be done the HEPA vacuum brakes and repaired vacuum cleaner as described in (2) above Grinding Grinding riveting cleaner and remaining dust wiped shall a be cleaned such such cleaner approved for asbestos dampened dampened used cloth cloth NIOSH certified respirator during during cleaning '. 6. If not ance ance shall be established effect , respirator program with Occupational Safety and Health established in accordaccord- * Standard Title 29 U.S. Code of Federal Regulations CFR Part 1910.134 containing asbestos dust cloths or brushes HEPA vacuum cleaner filters *. and all liquid used for used for iping brake and clutch assemblies with U.S. Environmental shall ce disposed of in accordance eet brushing the the These regulations state EPA regulations Protection Agency or oth- othe waste shall be disposed of in sealed impermeable asbestos criteria criteria asbestos asbestos at a disposal site which meets er containers shall display following following warn- label Also, the baste containers sufficient sufficient and contrast contrast to label or ta6 printed in letters to be visible and legible Asbestos . Avoid Breathing Fibers Dust Cause SerSioeusrious Hara Hars Asbestcs Dust May Cause * Breathing disposal disposal detailed detailed in asbestcs The 40 Part Subparts Subparts A and B. Tleae oe) CFR, Part 61, Subparts C-3 @& ee EE ce RTE SO Stamm! s . ; me, : approved for asbestos shall be worn during 8. A 8. certified respirator removal which approved for asbestos removal vacuum vacuum persitted in work areas Consumption of food beverages shall not be 9. Consumption areas exists . area shall not permitted permitted where asbestos consumption consumption &- separate from work area 50 as to for be separate dust contamination gainst asbestos of asbestos fi- employee exposed to airborne concentrations 10. 10. If employee exceed the OSHA ceiling level the OSHA requirement fi- bers which requirement regard- regard- change rooms locker etc. a8 ing special clothing D shall be followed 29 CFR Part 1910.1001 a = . the &-hour tinesverght- standard as of July , 1070 states The OSHA asbestos fibers to which any TWA airborne concentrations of asbestos ed average than micrometers micromerers shall not exceed fibers fibers longer employee say be exposed m cc ceiling ceiling aire cubic centimeter of air fibers in length per not exceed exceed which no employee may exposed exposed berne concentration to 10 fibers 75 m'cc be fibers wm with a permis- permis- an hour of 0.5 fibers sible ceiling 1975 proposed exceeding of fibers fibers wa cc any period not exceeding minutes minutes currently asbestos recommends the TWA exposure exposure asbestos fibers 5 currently 0.5 fibers fibers ce for fer any 15 minute sampling va cewith & ceiling exposure ; any 15-aiaute sampling period ame ears we RECOMMENDATIONS fiber exposure exists during The data from this study that airborne The especially during fiber exposure exists brake servicing operations assembly assembly cleaning the exposures reported do not during While While exists since at represent 100 asbestos asbestos fiber health hazard still a potential the fibers fiber types may be least Also Also other are asbestos animal animal and size may be more pathogenic suggest fiber shape studies suggest than chemi activity and the important nature terms terms biological cal nature for possibility exists for asbestos fiber concentrations exposure such higher exposure and there fibers there is known safe asbestos fiber length Since workers reo study of union vehicular saintenance clinical evidence from from with evidence of ray abnormalities consistent that over 25 had perts health ha-ard exists conclusion is that a potential asbestosis the prudent Therefore apprefr= of brake maintenance operations during the performance especially during brake for reducing fiber exposures iate control measures facilities should be instituted at brake maintenance This assembly vacuum cleaning sould remove be accomplished by using an appropriate all any any system brake assemblies drums drums to reacve all dust from further further blow air must eliminated eliminated protect of brake dust by compressed respiratory protec- of the brake mechanics personal personal tion pregram should wearing wearing NIOSH NIOSH should be initiated This would include approved respirators fitting rou- rou- roue for asbestos program program proper fitting tine maintenance the replacing replacing fil- file for respirator cleaning ters peak exposure only be neces- neces- data indicates it would sary for mechanics mechanics to respirators assembly performing performing assembly minimize wear respirators cleaning cleaning order vehicular mechan- mechanexposures exposures Th order CO pinimise asbestos pleaning, 28 NOTE Strict adherence to the above procedures should minimize exposures brake and cluth servicing These recommendations are to employee during based on the results of research conducted by NIOSH Prepared By Hazard Evaluations and Field Studies Division of Surveillance National Institute for Occupational Safety and Health Cincinnati Ohio a ~ J