Document zz28XGEQddzOXBO7QmE3z80Ma

FILE NAME: Flooring (FLR) DATE: 1993 Oct DOC#: FLR011 DOCUMENT DESCRIPTION: EPA Report - Project Summary - Airborne Asbestos Concentrations During Buffing of Resilient Floor Tile i&EPA United States Environmental Protection Agency__________ _________________ Research and Development Risk Reduction Engineering Laboratory Cincinnati, OH 45268 EPA/600/SR-93/159 ________ October 1993 Project Summary Airborne Asbestos Concentrations During Buffing of Resilient Floor Tile A study was conducted to determine the level of airborne asbestos concentra tions during routine spray-buffing of as bestos-containing floor tiles at 17 schools in northern, central, and southern New Jersey. Although the schools selected do not represent a statistical random sample, they do represent a cross section of floor conditions and floor-care m aintenance practices. Increased airborne asbestos lev els during spray-buffing were measured at 12 of the 17 schools. The increase was statistically significant at 7 of the 17 schools. Overall, the mean relative increase in airborne asbestos concentrations dur ing spray-buffing with the high-speed ma chines (1000 to 1500 rpm) was statistically significantly higher than that during buff ing with low-speed machines (175 to 330 rpm). Machine speed appeared to have a significant effect on the structure mor phology of the airborne asbestos struc tures generated during spray-buffing. Re sults of the study indicate that spray-buff ing can generate asbestos-containing par ticles from the surface of asbestos-con taining resilient floor tile. The estimated 8hr time-weighted average (TWA) of total fiber concentrations (0.093 f/cm2maximum) in the breathing zone of the machine op erators (as determined by phase contrast microscopy [PCM]) did not exceed the Occupational Safety and Health Adminis tration (OSHA) action level of 0.1 fibers per cubic centim eter (f/cm3 ), 8-hr TWA. This Project Summary was developed by EPA's Risk Reduction Engineering Laboratory, Cincinnati, OH, to announce key findings o f the research project that is fully documented in a separate report of the same title (see Project Report order ing information at back). Introduction Although no longer manufactured in the United States, asbestos-containing resilient floor tiles are installed in residential dwellings, institutions, commercial and public office build ings, and industrial facilities. The organic ma trix in floor tiles may be either asphalt or polyvinyl chloride, and their dimensions are either 9 in. by 9 in. or 12 in. by 12 in. The asbestos in nearly all floor tiles is chrysotile, which Is dispersed throughout the thickness of the tile. Although these floor tiles are con sidered nonfriable, the frictional forces ex erted on these materials during routine floorcare maintenance operations can generate asbestos-containing particles. The principal types of maintenance per formed routinely on resilient floor tiles include spray-buffing and dry burnishing, and wet scrubbing and stripping followed by refinish ing. The U.S. Environmental Protection Agency (EPA), school districts, and the Resil ient Floor Covering Institute have monitored airborne asbestos levels during wet stripping of asbestos-containing floor tiles. These stud ies have shown elevated levels of asbestos structures in the air during the stripping op eration (based on transmission electron mi croscopy [TEM]), but the 8-hr TWA concen trations (based on PCM) were below the OSHA permissible exposure limit and action level of 0.2 and 0.1 f/cm3of air, respectively. If the action level is exceeded, periodic per sonal air monitoring, employee training, and medical surveillance are required (29 CFR 1910.1001). The results of the two analytical techniques differ mostly because PCM does Kjtfy Printed on Recycled Paper not detect the smaller fibers (<5 pm in length and <0.25 pm in width) as measured by TEM. Also, the OSHA methodology requires a length to width ratio (aspect ratio) of 3:1 or greater whereas the TEM methodology has an aspect ratio of 5:1 or greater. In response to concerns raised by school districts and building managers regarding the release of asbestos structures during stripping opera tions, the EPA issued interim guidance on appropriate procedures for the stripping of asbestos-containing floor coverings. Little data are available for evaluating the extent of asbestos structures released during other floor-care maintenance procedures, such as spray-buffing. Spray-buffing is the restor ative maintenance of a previously polished floor by use of a suitable floor-polishing ma chine immediately after the surface has been mist-sprayed with an appropriate product whereby the wet application is buffed to dry ness. The levels of airborne asbestos struc tures released during spray-buffing could be higher than those during wet stripping, espe cially if the floor has been poorly maintained (i.e., minimal wax layer), is worn, or is other wise damaged. The Risk Reduction Engineering Labora tory (RREL) of the U.S. EPA and the Environ mental Health Service (EHS) of the New Jersey Department of Health (NJDOH) con ducted a study to evaluate airborne asbestos concentrations during routine spray-buffing of asbestos-containing floor tile. The primary ob jectives of this study were (1) to determine the airborne asbestos concentrations during routine spray-buffing of asbestos-containing resilient floor tile in a cross section of schools in northern, central, and southern New Jer sey, and (2) to compare the fiber concentra tions measured by PCM during routine spray buffing of asbestos-containing floor tile with the OSHA action level of 0.1 f/cm3 of air, 8-hr TWA (29CFR1910.1001). Study Sites This study was conducted at 17 schools, distributed among eight school districts, in northern, central, and southern New Jersey. Although these schools do not represent a statistical random sample, they do represent a cross section of floor conditions and floorcare maintenance operations. Access to the schools was coordinated directly by the Environmental Health Service of the New Jersey Department of Health (EHSNJDOH). The EHS-NJDOH collected bulk samples of all floor tiles; and documented floor-care practices, floor conditions, and char acteristics of the floor-buffing equipment and materials in each school, as well as other variables that might have an effect on the release of asbestos structures. In all of the schools, the existing custodial staff performed the floor-care maintenance operations. The floors were prepared (i.e., dry and/or wet-mopped) and spray-buffed in accordance with established practices and procedures at the respective schools. Sampling Strategy The first study objective was to determine whether airborne asbestos concentrations in creased during the spray-buffing of floor tile. This was addressed by collecting air samples before and during floor-buffing operations. A maximum of two distinct areas were tested in each school studied. Immediately before buff ing operations began, three baseline, fixedstation, area air samples were collected in each test area under normal building condi tions (i.e., no intentional air disturbance be yond that attributable to normal occupancy activity in the area). Three personal breath ing-zone samples were collected during buff ing operations for comparison with the baseline samples. These samples also were taken under normal occupancy conditions (i.e., no air disturbance beyond that attributable to the buffing itself). These samples were collected in the breathing zone of the buffing machine operators so they would be representative of airborne asbestos levels during spray-buffing operations. The three baseline and three per sonal breathing zone samples were analyzed by TEM. The second study objective was to com pare total fiber concentrations during buffing operations with the OSHA action level of 0.1 f/cm3, 8-hr TWA. This was achieved by col lecting one sample in the breathing zone of the machine operator during the spray-buff ing in each area. These samples were col lected in accordance with OSHA sampling protocols and analyzed by PCM. To confirm the percentage and type of asbestos in the floor tile, bulk samples of each type of floor tile present in each school were collected. Sampling Methods Fixed-Station Area A ir Samples The baseline, fixed-station, area air samples were collected on open-face, 25-mm-diameter, 0.45-pm-pore-size, mixed cellulose es ter (MCE) filters with a 5-pm-pore-size MCE diffusing filter and a cellulose support pad contained in a three-piece cassette. The filter cassettes were positioned on tripods approxi mately 5 ft above the floor, with the filter face at a 45 angle toward the floor. The filter assembly was attached to an electric-pow ered (110 VAC) 1/6-horsepower vacuum pump operating at a flow rate of approxi mately 9 L/min. Air volumes ranged from 564 to 916 L. The sampling pumps were cali brated with a precision rotameter both before and after sampling. Personal Breathing Zone A ir Samples Three personal breathing zone air samples were collected on the same filters described in the previous section and were analyzed by TEM. A fourth personal breathing zone sample was collected on a 25-mm-diameter, 0.8-pmpore-size MCE filter, and a cellulose support pad contained in a three-piece cassette with a 50-mm conductive extension cowl. This fourth personal breathing zone sample was collected in accordance with OSHA protocols and analyzed by PCM. The four filter cassettes were positioned in the breathing zone of the buffing machine operator. Each filter was attached to approxi mately 50 ft of Tygon tubing that was at tached to an electric-powered (110 VAC) 176horsepower vacuum pump operating at a flow rate of approximately 9 L/min. Air vol umes ranged from 617 to 970 L. To achieve the target air volume of 600 L in the time required to spray-buff the test area, traditional battery-powered, personal sampling pumps could not be used because of their limited airflow rates (approximately 2 L/min with the 0.45-pm-pore-size MCE filter). Bulk Floor Tile Samples Bulk samples were collected of each type of floor tile present in each school. Each sample consisted of a 2-in. by 2-in. section of floor tile. A 2-in. by 2-in. template was used to delineate the area on the floor tile. A hammer and wood chisel were used to remove the tile, which was then placed in a labeled Ziploc plastic bag. The exact location of the sample was recorded on a plan drawing of the build ing. A n alytical M ethods A ir Samples The 0.45-pm-pore-size MCE filters were prepared and analyzed in accordance with the nonmandatory TEM method specified in the Asbestos Hazard Emergency Response Act (AHERA) Final Rule (October 30, 1987; 40 CFR Part 763). Each of the 0.8-pm-poresize MCE membrane filters was analyzed by PCM. These 0.8 pm sample filters were pre pared and analyzed according to the NIOSH 7400 protocol (Revision 3, June 5, 1989, 2 National Institute of Occupational Safety and Health Manual of Analytical Methods). Bulk Floor Tile Samples The type and percentage of asbestos in the floor tile were determined by polarized light microscopy analysis in accordance with the EPA test method "Interim Method for Determination of Asbestos in Bulk Insulation Samples" (EPA 600/M4-82-020). A confirma tory analysis was performed on floor tile from 8 of the 17 schools. The samples were ana lyzed by TEM in accordance with Chatfield's Method (SOP-1988-02, Revision No. 1: Analy sis of Resilient Floor Tile). Portions of a freshly fractured edge of the bulk samples were ana lyzed by scanning electron microscopy to examine the condition of the floor tile surface. Statistical Methods Descriptive statistics were calculated for each school and each area within a school. These descriptive statistics Included the sample size; arithmetic mean, minimum, and maximum airborne asbestos concentrations; and the arithmetic standard deviation. A two-factor analysis of variance (ANOVA) was used to compare airborne asbestos con centrations before and during floor buffing. Each school was considered separately. The experimental factors in the ANOVA analysis were the sample period (baseline, during) and area within a school (A or B). If only one area was studied at a school, the analysis was reduced to a one-factor ANOVA, which Is equivalent to a Student's t-test. Quality Assurance Specific quality assurance procedures out lined in the AHERA rule were used to ensure the precision of the collection and analysis of air samples; these included filter lot blanks, open and closed field blanks, and repeated sample analyses (replicate and duplicate analyses). Results and Discussion Study-Site Characteristics Resilient Floor Tile The resilient flooring in the 28 study sites (representing 17 schools) included mostly 9in. by 9-in. tiles and some 12-in. by 12-in. tiles. Although the asbestos content of the tiles ranged from 1% to 38%, the content of most of the tiles exceeded 10%. The spraybuffed areas ranged from 727 to 3386 ft2; the average area was approximately 2150 ft2. Any floor areas with damaged (e.g., broken) or missing tiles were isolated to prevent their contact with the buffing machine. Floor Care Maintenance Practices Sixteen of the 17 schools used a black pad for stripping the floors, whereas EPA's interim procedure guidelines for the stripping of resil ient floor coverings recommend the use of the "least abrasive pad possible". The schools wet-stripped and refinished the floors one to three times a year (during the summer, win ter, or spring breaks). The floors were dry- and/or wet-mopped before they were spray-buffed. All of the schools dry-mopped the floors, and nine of the schools both dry and wet-mopped the floors. The floors are typically spray-buffed once a year; however, some schools spraybuffed the floors one to three times each week. Buffing Equipment and Materials Twelve of the schools used buffing ma chines operating at 1000 to 1500 rpm and five used buffing machines operating at 175 to 330 rpm. The appropriate buffing pad (i.e., a white pad with high-speed machines and a red pad with low-speed machines) was used at all of the schools except two: school No. 1 used a red pad with a high-speed machine, and school No. 13 used a green pad (de signed for heavy scrubbing and light stripping applications) with a low-speed machine. Airborne Asbestos Concentrations Before and During Spray-Buffing Three samples were collected before and three during routine spray-buffing of asbes tos-containing floor tile in each area within a school. Table 1 presents the descriptive sta tistics (i.e., mean, minimum, maximum, and standard deviation) separately for each school/ area combination and each sampling period (i.e., baseline and during spray-buffing). Fig ure 1 shows the average airborne asbestos concentrations at each area before and dur ing spray-buffing. Increased airborne asbestos levels during spray-buffing were noted at 12 of the 17 schools. The increase was statistically signifi cant at seven of these schools (Nos. 1,5, 6, 7, 12, 14, and 17). When compared with baseline measurements taken before buffing, airborne asbestos concentrations were quali tatively the same or lower during buffing at the remaining five schools (Nos. 2, 4, 9, 10, and 16). Overall, the mean relative increase in air borne asbestos concentrations during spray buffing with the high-speed machines (1000 to 1500 rpm) was significantly higher (p=0.0326) than the relative increase during spray-buffing with the low-speed machines (175 to 330 rpm). On average, airborne as bestos concentrations were approximately 5 times higher during spray-buffing than before spray-buffing with the higher speed machines; whereas, spray-buffing with the lower-speed machines showed a 2-fold increase. Airborne Asbestos Concentrations Based on Frequency o f Spray Buffing Spray-buffing is routinely performed (one or more times weekly) at 7 schools, whereas spray-buffing is performed less frequently (once per month to once per year) at the remaining 10 schools. The mean airborne asbestos concentrations measured before buffing at the schools in which spray-buffing is routinely performed (0.035 s/cm3) was sig nificantly greater (p=0.0004) than the mean baseline concentration measured at schools in which spray-buffing is performed less fre quently (0.007 s/cnf). Personal Breathing Zone Concentrations of Total Fibers Table 2 presents total fiber concentrations measured in the machine operator's breath ing zone during spray-buffing, as determined by PCM. The actual time spent buffing the floors ranged from 64 to 97 min. School maintenance workers do not typi cally spray-buff floors for a full 8-hr work shift. According to school custodians at the five sites (Nos. 6A, 10A, 11A, 13B, and 16B) that showed measured levels above 0.1 f/cm3, the average time spent buffing floors on a typical day ranges from 1.5 to 2.5 hr. Assuming that a maintenance worker spends no more than 2.5 hr/day buffing the floor and has no additional exposure to asbestos for the remainder of the day, the estimated 8-hr TW A concentrations for all of these sites would be less than the OSHA action level of 0.1 f/cm 3, 8-hr TWA. The maximum estimated 8-hr TWA exposure concentra tion (0.093 f/cm3, 8-hr TWA) was mea sured at Site 11A. M orphology and Size Distributions o f Asbestos Structures The TEM analysis of the 163 samples collected before and during spray-buffing yielded a total of 4598 asbestos struc tures, of which more than 99% were chrysotile and less than 1% were amphibole. The asbestos in nearly all floor tiles is chrysotile. Overall, the asbestos structures were primarily matrices (approximately 80%) and to a lesser extent, fibers, clus ters, and bundles. The structure morphology for asbestos structures observed before (I.e., baseline) 3 Table 1. Summary of Airborne Asbestos Concentrations Measured By TEM Before and During Buffing o f Floor Tile Site Mean Baseline Minimum Maximum Asbestos Concentration, s/crrA (N=3) Standard Deviation Mean 1A 0.004 1B 0.001 2A 0.006 3A 0.001 3B 0 4A* 0 5A 0.009 6A 0.030 6B 0.029 7A 0.003 7B 0.008 8A 0.011 8Bf 0.041 9A 0.010 10A 0.086 10B 0.038 11A 0.033 11B 0.029 12A 0.012 12B 0.065 13A 0.015 13B 0.194 14A 0.006 15A 0.094 16A 0.001 16B 0.003 17A 0.001 17B 0.050 0 0 0 0 0 0 0.005 0 0.015 0 0.005 0.005 0 0 0 0.030 0.020 0.005 0.009 0.029 0 0.051 0.005 0.058 0 0 0 0.024 0.009 0.005 0.010 0.005 0 0 0.014 0.076 0.054 0.010 0.014 0.020 0.103 0.020 0.254 0.045 0.054 0.069 0.014 0.113 0.040 0.390 0.010 0.126 0.005 0.005 0.005 0.065 0.005 0.003 0.006 0.003 0 0 0.005 0.040 0.021 0.006 0.005 0.008 0.055 0.010 0.145 0.008 0.018 0.034 0.003 0.043 0.022 0.175 0.003 0.034 0.003 0.003 0.003 0.023 0.014 0.013 0.003 0.011 0.003 0 0.107 0.163 0.205 0.145 0.414 0.025 - 0.003 0.067 0.032 0.056 0.077 0.067 0.096 0.082 0.290 0.052 0.151 0.001 0 0.056 0.114 ' Summary statistics are based on two samples (N=2). f The samples collected during spray-buffing were too heavily loaded with particulate to count. Minimum 0.010 0.005 0 0 0 0 0.088 0.065 0.137 0.097 0.379 0.015 _ 0 0.033 0.029 0.015 0.067 0.043 0.062 0.015 0.225 0.020 0.102 0 0 0.052 0.035 Maximum 0.019 0.019 0.005 0.025 0.009 0 0.123 0.302 0.291 0.179 0.464 0.030 0.009 0.094 0.035 0.097 0.090 0.113 0.151 0.206 0.329 0.087 0.216 0.004 0 0.059 0.189 Standard Deviatior 0.005 0.007 0.003 0.013 0.005 0 0.018 0.123 0.078 0.043 0.044 0.009 0.005 0.031 0.003 0.058 0.012 0.039 0.048 0.040 0.057 0.034 0.059 0.002 0 0.004 0.077 low-speed buffing was comparable with that observed during low-speed buffing. That is, sim ilar percentages of fibers, bundles, clusters, and matrices were ob served both before and during low-speed buffing. The structure morphologies for as bestos structures observed during high speed buffing, however, were distinctly dif ferent; these morphologies showed that the percentage of asbestos fibers observed during high-speed buffing was approxi mately 2.5 tim es greater than the percent age of fibers observed before buffing. In contrast, the percentage of asbestos ma trices were greater before high-speed buff ing than during buffing. One possible ex planation for a decrease In the number of asbestos matrices during buffing is that the high-speed buffing pulverizes any as bestos-containing particles lying on the sur face of the floor and/or any particles con tained In the wax layer on the floor tile. This could also explain the increase in the percentage of asbestos fibers during high speed buffing. Another possible explana tion fo r the increase In the percentage of asbestos fibers during high-speed buffing could be the abrasion of surficial fibers from the floor tile. Overall, less than 1% of the asbestos fibers measured before and during were greater than 5 pm in length. Although comparable structure size distributions were observed before and during low-speed buffing, a larger percentage of the structures observed during high-speed buff ing were less than 1 pm compared to structures observed before high-speed buffing. The In creased number of structures less than 1 pm in length could result from (1) the pulverization of asbestos structures on the floor surface and/or asbestos structures contained In the wax layer, and/or (2) the abrasion of surficial fibers from the floor tile. Conclusions Spray-buffing can cause asbestos structures to be generated from the surface of asbestoscontaining resilient floor tile. Increased airborne asbestos concentrations during spray-buffing were measured at 12 of the 17 schools studied. The increase was statistically significant at seven of these schools. Overall, the mean relative increase in air borne asbestos concentrations during spray buffing with the high-speed machines (1000 to 1500 rpm) was significantly higher than the relative increase during spray-buffing with the low-speed machines (175 to 330 rpm). On average, airborne asbestos concentrations were approximately 5 times higher during than before spray-buffing with the high speed machines; whereas, spray-buffing with the low-speed ma chines showed a 2-fold increase. Machine speed appears to have a significant effect on the structure morphology of the air borne asbestos structures generated during spray-buffing. The percentage of asbestos fi bers observed during high-speed buffing was approximately 2.5 times greater than that be fore buffing; whereas, the percentage of asbes tos fibers observed during low-speed buffing was approximately 1.3 times greater. The per centage of asbestos matrices measured during high-speed buffing were approximately 12 times lower than before buffing; whereas, the percent 4 Study Site Figure 1. A verage airborne asbestos concentrations (measuredby TEM) before and during buffing ofasbestos-containing resilient floortile (continued). % So co Oto o CO <D tOo CD -Eop 7A Figure 1. (continued). 7B 8A 9A 10A 10B 11A Study Site 11B 12A 12B 5 Sampling period H Baseline I____ ; During buffing Airborne Asbestos Concentration, s/crri 13A 13B 14A 15A 16A 16B 17A 17B Figure 1. (concluded). Study Site 6 Table 2. Total Fiber Concentrations During Buffing o f Resilient Floor Tile (As Measured by PCM) Total Fiber Concentration, Site f/cm3 1A 1B 2A 3A 3B 4A 5A* 6A 6B* 7A 7B* 8A` 8B* 9A 10A 10B 11A 11B 12A 12B 13A 13B 14A 15A 16A 16B 17A 17B 0.033 0.034 0.078 0.077 0.076 0.024 - 0.130 - 0.048 - - - 0.030 0.133 0.061 0.295 0.065 0.067 0.070 0.085 0.220 0.042 0.076 0.080 0.104 0.027 0.055 * Samples were alt too heavily loaded with par ticulate to count. age of asbestos matrices measured during lowspeed buffing was essentially unchanged (i.e., <0.4% lower). The estimated 8-hr TWA of total fiber con centrations (0.093 f/cm3maximum) in the breath ing zone of the machine operators (as deter mined by PCM) did not exceed the OSHA action level of 0.1 f/cm3, &+ir TWA. R ecom m endations Further research is recommended to study the effect of buffing methods on the release of asbestos structures from the surface of asbestos-containing resilient floor tiles. A study should be designed to evaluate the extent of asbestos release during application of the two buffing methods (low-speed spray-buffing and high speed dry-buffing) on three levels of floor care (poor, intermediate, and good). The results of this study would define the need for and nature of guidance for the buffing of asbestos-contain ing resilient floor tiles. The full report was submitted in fulfillment of Contract No. 68-D2-0058 by Environmental Quality Management, Inc. under subcontract to Pacific Environmental Services, Inc. through the sponsorship of the U.S. Environmental Protec tion Agency. * U . S . GOVERNMENT PRINTING OFFICE: 19*3 - 730-071/80092 7 This Project Summary was prepared by the staff of Environmental Quality Management, Inc., Cincinnati, OH 45240 and Environmental Health Service, New Jersey Department of Health, Trenton, NJ 08625 Aaron R. M artin is the EPA Project Officer Alva Edwards is the Technical Project Officer (see below) The complete report, entitled "Airborne Asbestos Concentrations During Buffing of Resilient Floor Tile," (Order No. PB93-227 551/AS; Cost: $27.00, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 Telephone: 703-487-4650 The Technical Project Officer can be contacted at: Risk Reduction Engineering Laboratory U.S. Environmental Protection Agency Cincinnati, OH 45268 United States Environmental Protection Agency Center for Environmental Research Information Cincinnati, OH 45268 Official Business Penalty for Private Use $300 EPA/600/SR-93/159 BULK RATE POSTAGE & FEES PAID EPA PERMIT No. G-35