Document pmqXkmGG1pBenyK05Y7wqMdJj

iWitl'BIkMIHMill-li ISSfeliSi 6CS (SlfPDN-P HASKELL LABORATORY mmmm sma J. R. GIBSON CR& D HASKELL LABORATORY RESPIRATOR WORKPLACE PROTECTION FACTORS FOR ASBESTOS (Haskell Laboratory Report No. 462-84; MR-5557-001) SUMMARY AND BACKGROUND v.'orkpiace protection factors for elastomeric and single use naif-face respirators were measured during asbestos removal operations. The operations consisted of asbestos removal from a ceiling (fire proofing) and removal of pipe insulation. The use of water/surfactant solutions to spray fire proofing and insulation resulted in conditions of high humidity for indoors operations. Out-of-doors operations were also under high humidity conditions since light rain occurred on two of four days of sampling. Temperatures^ for both operations were in the 6 5-35 F range. The respirators were used in the context of a respirator program that followed the guidance in 29 CFR 1910.134 and ANSI 288.2 (1980) including proper respirator selection and fit testing . A total of seventeen volunteers participated in the study. One or two workplace protection factors were determined for each respirator for which the fit test had been passed. The respirators tested were: One successfully fitted elastomeric facepiece respirator chosen for comfort from six respirators (MSA Comfo II and Survivair 2000 brands - small, medium and large sizes). These respirators were tested using dust, fume and mist and high efficiency filters. Each of three disposable respirators successfully fitted (3M 9910, 3M 8 710 -and American Optical R 10 50). A successfully fitted North 7700 elastomeric facepiece respirator, chosen from the small, medium or large size facepieces . DUP 0949990.215 DU 040267 ; il 8.8131- Siimilfflii in addition two workplace protection factor measurements were made fo*t a self-contained breathing apparatus operated in the pressure-demand mode. Results show that all respirators tested, reliably provide workplace protection factors of ten or greater, except the AO RIO 50, which reliably provides a protection factor of five or greater, based on estimates of lower 5th percentile. These results are consistent with information supplied to the OSHA asbestos record by Los Alamos National Laboratory which reported on the.penetration of asbestos through respirator filter media. Results for the self-contained breathing apparatus suggest that it may not provide appreciuDly better protection than the two better disposable respirators and the elastomeric facepiece respirators, though it presents a considerable stress and hazard of falling because of it's weight and awkwardness. Myhre et al.^2^ and Raven^2^ have shown that pressure-demand respirators do not maintain positive pressure inside the facepiece when workloads are increased from rest conditions. This may explain, in part, why the pressure-demand and self-contained breathing apparatus did not provide superior protection. PROCEDURE Prior to testing, each person was trained in the selection and fit testing of respirators using the National Paint and Coatings Association Training Program . Each was then fit tested using the saccharin fit test' . Fit test results are given in Table V. Respirators selected for use ar.d vendors are listed in Table I. -- Two individuals were also trained in use of a pressure-demand self-contained breathing apparatus. Fit testing was not done, as it is not required for pressure-demand equipment per the ANSI Z88.2 (1980) standard. During sample collection, each participant was observed continually to ensure that the sample train remained intact and did not interfere with the respirator seal on the face, and to note occurrences which might have affected respirator performance, such 3s movement of the respirator on the face. The participants were very busy with their work activities and soon ignored the presence of the researchers. AIR SAMPLING AND ANALYSIS ____ To determine the workplace protection factors, concurrent samples were taken from inside the respirator (in-mask) at nose level and outside the respirator at the lapel (lapel). Closed-face Glasrock (#1505) cassette filter holders fitted with half inch extenders and probes developed by NIOSH ' were used for both the in-mask and lapel samples. The sample probes are specially designed to minimize the loss of particulates. The cassettes contained 0.8 urn, 25mm cellulose ester filters. DU 040268 DUP 0949990.: The^sample trains were calibrated before and after taking each sample using a mass flow meter. The mass flow meter was calibrated against a bubble flow meter at the beginning and end of the study. A flow rate of 2 Lpm was used for the in-mask samples. Lapel samples were taken at 0.5-1.0 Lpm to avoid overloading. Samples were collected for a one- to two-hour period. Each sample represented a single wearing of the respirator. Fiber counts were done per NIOSH method p&CAM 239(phase contract microscopy), except that the triacetin/acetone mounting method was used as described in NIOSH method 7400Counting was done according to the P&CAM 239 rules (the "A" counting rules in method 7400). Five hundred fields were counted for in-mask samples to increase analytical sensitivity. All analyses were done by one counter who participates successfully in the American Industrial Hygiene Association's proficiency Analytical Testing quality assurance program. Concentrations were calculated from the actual number of fibers counted (even if fewer than 50 fibers were counted) per the formulas in the NIOSH method. NIOSH method P&CAM 23-9 reports a coefficient of variation of 0.12 which applies to lapel samples in this study. We estimate that the coefficient of variation for the in-mask samples is 0.4 at the median in-facepiecc concentration and fiber count (Table III) . Transmission electron microscopic analyses were also done on selected samples to obtain data on small fiber penetration and size distribution. All field and analytical data are retained in the MR-5557 file . SAMPLING AND ANALYSIS METHOD VERIFICATION In-mask sampling required use of closed-face filter cassettes. We used Glasrock #1505 25mm filter cassettes which have a unique tapered design for the outlet and a half inch extender which improves the deposition patterns^ . To minimize sample loss, the N1.0SH probe was used to withdraw in-mask samples. To eliminate possible bias, the same closed-face/probed cassette was used for both in-mask and lapel samples. To document whether concentrations determined from closed-face/probe cassette sampling differed-from open-face sampling, twelve area samples were taken using both methods. Results are compared in Table II with Student's t and Variance Ratio tests^ . The two sampling methods were found to give similar results with no significant bias or difference in precision. DUP 0949990.217 D\J 040269 RESULTg^AND DISCUSSION Transmission electron microscopic analyses were done on four lapel samples by Electron^Microscopy Service Laboratories, Inc., Camden, New Jersey. The resultant distributions of fiber diameters and lengths are shown in Figures 1 and 2. Fiber diameters and lengths covered a wide range. The overall median concentrations of fibers for in-mask and lapel samples are given In Table III. The median number of fibers counted for in-mask (500 fields counted) and lapel (<100 field counted) samples are also given in Table III. ~ Cumulative distributions, geometric means, geometric standard deviations, best estimates of 5th percentiles and lists of workplace protection factors are given in Figures 3 through 8 for each respirator. The distributions of workplace protection factors were found to be approximately lognormal for all respirators studied. Therefore, logs were used for the plots, geometric means are reported as the proper measure of central tendancy and geometric standard deviations are reported as the proper measure of variability. Best estimates of 5th percentiles represent the workplace protection factors that most (95%) respirator users are expected to obtain from each respirator. Distribution plots and geometric standard deviations include variability from the sampling and analytical method.as well as from the workplace protection factors. The unavoidable inclusion of the sampling and analytical variability in the plots results in best estimates of 5th percentiles which are conservative (lower than actual). This should be considered in evaluating results. Workplace protection factors were determined for a selfcontained breathing apparatus for two individuals. Results are reported in Table IV. Table V gives geometric means, geometric standard deviations, best estimates of the 5th percentile, and ratios of participants passing the fit test for each respirator studied. A Bonferroni ^ test for differences (p=0.05) was done and results are given in Table V. Workplace protection factors for the 3M 9910 were found to.be significantly higher than those for the AO R1050. No other significant differences were found. The importance of doing a fit'test is apparent from the fit test results in Table V. The relatively low results for the AO R1050 are likely due to poorer filter efficiency for asbestos, reported by Dr. Ortiz of Los Alamos National Laboratory^'. -4 - DUP 0949990.218 DU 040270 The ^unexpected comparability of the results from the 3M disposable respirators, and elastomeric facepiece respirators with both dustS mist and fume filters >_nh high efficiency filters may be explained by several factors. First, because the filter efficiency is high (~99.9%), the limiting factor in performance of the respirators is likely face fit, not filter efficiency (except for the AO R1050 as noted above). Since the same fit test was used to select good fitting respirators for the study, comparable face-fit results would be expected. In addition, the researchers noted a tendency for elastomeric respirators to slip around when some wearers' faces became wet with the water/surfactantT spray. This did not occur with the disposable respirators because their fibrous material of construction clung to the skin. It is particularly noteworthy that the workplace protection factors for the self-contained breathing apparatus were not superior to the better disposable and elastomeric respirators. Myhre 2 and Raven^3 have shown that at workloads exceeding approximately 35% of maximal aerobic capacity pressure inside the facepiece of pressure-demand type respirators does not remain positive with respect to the surrounding atmosphere. This would provide an opportunity for airborne asbestos to be drawn into the facepiece. The volunteers who wore the self-contained breathing apparatus complained of Stress and discomfort due to its weight and bulk. , Movement and balance were difficult and one volunteer almost fell from a step ladder as a result. Based on their observations, the researchers believe that routine use of self-contained breathing apparatuses for asbestos removal would likely result in injuries, in view of the large amount of climbing involved. Certainly, acceptance will be much poorer than for the other respirators studied, due to discomfort which would discourage respirator use. Transmission e lectron microscopic analysis results were also used to determine workplace protection factors for thin fibers (Table VI). Resul ts for small diameter (<0.2um) fibers do not appear to differ f rom those for large diameter (>0.2um) fibers, for 5 um or longer lengths. Thus, results for fibers visible with the phase con trast method (>0.2um diameter) appear to be representative of those for smaller diameter fibers for the 3M 8710 and 9910 , and for elastomeric respirators with dust, fume and mist and high efficiency filters. CONCLUSIONS 1. All respirators tested provided protection against asbestos. The American Optical R1050 disposable respirator reliably provided workplace protection factors of 5 or greater. The 3M 9910, 3M 8710, and elastomeric half-face respirators with both dust, fume and mist and high efficiency filters reliably provided workplace protection factors of 10 or greater. _5 DU 040271 DUP 0949990.219 2* Use of higher efficiency filters did not appear to improve the*workplace protector factors of the elastomeric respirators. 3. workplace protection factor measurements for a pressure demand self-contained breathing apparatus were not significantly higher than those for the better disposable and elastomeric respirators. Comments from the test volunteers and observations indicate that acceptance of the selfcontained breathing apparatus would be poorer than that of the other respirators tested. In addition, it presents a significant risk of tripping or falling, where removal work requires climbing ladders and working from scaffolding. 4. Transmission electron microscopic analyses suggest that for fibers longer than 5 um, the overall workplace penetration of small diameter (<0.2um) fibers is not higher than that of larger diameter fibers for the 3M 8710 and 3M 9910 disposable respirators nor for elastomeric respirators with dust, fume and mist or high efficiency filters. ACKNOWLEDGEMENTS __ The valuable collaboration and participation of Thomas J. Nelson in this study, and the perserverance and thoroughness of James E. Henry in doing microscopic analysis are gratefully acknowledged. Special acknowledgement is also due Robert L. Frye, C. Norman McLean, the study volunteers, and numerous other at the Kingston, Ontario site and the Potomic River site for their excellent cooperation and assistance. The assistance of JamesM. Kayser, James C. Piner, James Henry and Susan S. Mileti in doing the workplace studies is greatefully acknowledged, as is the peer review of Edwin C. Hyatt, Earle P. Shoub, and Charles E. Billings. E. REFERENCES 1. Ortiz, L. W. et al.: ' "Interim Report: Penetration of Respirator Filters by an Asbestos Aerosol." May 2, 1984 (Los Alamos National Laboratory). 2. Myhre, L. G., 8* D. Holden, F. W. Baumgardner and D. Tucker: Physiological Limits of Firefighters. unclassified Report #ESL-TR-79-06, AFESC, Tyndall AFB, Florida (June 1979). 3. Raven, p. B. et al.: "physiological Response to 'PressureDemand' Respirator-Wear", Am. Ind. Hyg. Assoc. J. 4 3( 10 ) : 77 3-781 (1982). 4. "Guide to Respirator Fit Testing" (1981), National Paint and Coating Association, Washington, D.C. -6- DUP 0949990.220 DU 040272 5. Liu, B. Y. U. et al.: "In-Mask Aerosol Sampling for Powered Air*Purifying Respirators", Am. Ind. Hyg. Assoc. J. 45(4) : 278-283 (1984) . 6. CJ. S. Department of Health, Education and Welfare: NIOSH Manual of Analytical Methods, Second Edition, Volume I (April 1977 ) 7. National Institute for Occupational Safety and Health, Method 7400, February 15, 1984. 8. Adams, M. J. et al., "Cassette Extenders: Effects on Chrysotile Fiber Deposition and Concentration Measurements", Presented at the American industrial Conference, May 24, 1983. 9. Snedecor, G. W. and W. G. Cochran: Statistical Methods, 7th Ed., Iowa State University Press, Ames, Iowa (1980). Report by: s ^____--____________ _ STEPHEN W. DIXON SECTION SUPERVISOR INDUSTRIAL HYGIENE Approved by: A. MICHAEL KAPLAN MANAGER - FIELD SERVICES SWD/tac/3.52 Date Issued: October 18, 1984 Attachments: Table I-VI, Figure 1-8 Number of pages in this report: 21 DUP 0949990.221 7 DU 040273 Respirator Name Survivair 2000 Comfo II 3M 8710 3M 9910 AO R1050 North 7700 Scott Air-Pak TABLE I Respirators Studied -- Type Elastomeric (silicone rubber) with dust, fume and mist and high efficiency filters Elastomeric (neoprene) with dust, fume and mist and high efficiency filters Disposable with nonadjustable staps Disposable with adjustable straps Disposable with nonadjustable straps Elastomeric (silicone rubber) with high efficiency filters Self-contained breathing apparatus, pressure-demand Vendor U.S.D. Corp. Mine Safety Appliance Co. 3M Company 3M Company American Optica Company North Company Scott Aviation DUP 0949990.222 HLR 462-84 8- DU 040274 TABLE II COMPARISON OF ASBESTOS SAMPLING METHODS (OPENV.-FAC"E " VE"RSU' S CLOSED-FACE WITH -P--R---O--B- E---) Parameter Mean Value 2.2 fibers/mL - open face filter cassette 2.3 fibers/mL - closed face cassette with probe Standard Deviation probe 0.264 fibers/mL - open face cassette 0.286 fibers/mL - closed face cassette with T Statistic* 1.28 Variance Ratio** 1.1-7 Data Open-face, cassette: 1.9, 1.9, 2.0 , 2.1 2.2, 2.3, 2.9 Closed-face cassette: 2.0 , 2.0 , 2.0 , 2.2 2.4, 2.5, 3.0 1, 2.1, 2.2, 2.2, 2.2, 3, 2.3, 2.3, 2.4, 2.4, * 1.28 is less than a comparison t statistic of 1.78 (p=0.05). Therefore, the means do not differ significantly. ** 1.17 is less than a comparison F statistic of 2.69 (p=0.05). Therefore, the variances (precision! of the methods do not differ significantly. DUP 0949990.223 HLR 462-84 9- DU 040275 TABLE III >* MEDIAN ASBESTOS CONCENTRATIONS AND COUNTS FOR WORKPLACE PROTECTION FACTOR STUDY Concentrations Inside Respirator Outside Respirator Counts Inside Filter Outside Filter 0.006 fibers/mL (8 HR. TWA ^ 0.003)* 2.6 fibers/mL (8 HR. TWA 1.3)* 9 fibers 130 fibers No more than four of eight work hours were spent doing asbestos removal. Therefore, a factor of 0.5 (4 HRS/8HRS) was applied to concentrations to estimate 8 HR TWA concentrations. DUP 0949990.224 HLR 462-84 10 - DU 040276 TABLE IV WORKPLACE PROTECTION FACTORS FOR SELF-CONTAINED BREATHING APPARATUS (PRESSURE DEMAND) Workplace Protection Factors:: 400 880 Geometric Mean: 620 DUP 0949990.225 HLR 462-84 - 11 - DU 040277 * TABLE V COMPARISON OF WORKPLACE PROTECTION FACTORS FOR SEVEN RESPIRATORS Respirator Number of Measurements Workplace Protection Factor Geometric Mean (Geom. S.D.) Ratio Passing Fit Test Lower 5th Percentile 3M 8710 18 - 3M 9910 14 AO R1050 7 Elastomeric/Dust, Fume and Mist Filter 17 Elastomeric/High Efficiency Filter 14 North 7700 High Efficiency Filter 14 Self-Contained Breathing Apparatus 2 310 (5.3) 580 (4 .2) 52 (4.2) 240 (6.3) 94 (3.0) 250 (6.9) 6 20 15/17 14/17 4/6 Not Tested Surv.-14/16 MSA-1/2 15/15 Not Tested 20 55 5 12 16 11 (Q j *Based on a Bonferroni tes_t at a 0.05 level of significance only the 3: 9910 and AO RIO 50 differed". DUP 0949990.226 HLR 462-84 12 - DU 040278 TABLE VI WORKPLACE PROTECTION FACTORS FROM TRANSMISSION ELECTRON MICROSCOPIC ANALYSES Respirator Workplace Protection Factor Fibers Exceeding 0.2 um All Diameter Fibers Diameter and 5 um Length* Exceeding 5 um Length* 3M 8710 3M 9910 Survivair 2000 with Dust, Mist and Fume Fi1 ter Survivair 2000 with High Efficiency Filter -- 330 47 28 21 120 41 29 19 *Those which would be counted by the standard phase contrast microscopy method. DUP 0949990.227 HLR 462-84 13 - DU 040279 -Haws r I ......- --- -.......... .................. --jEluLff-f-tl 1 '.-iiil .mii. - 7I NUMBER OF FIBERS to iM O o o o o o 7Q-Z3& dUH r> o o_ M c 3 0^F.^~O0>iSr,j^L~0i'.'-LF'i'-0i v-.VFvFsV-.VnV>V-FnVV,>.*`.VW`iX'-'>.V>N\V^sX\ c 53 > 2; m --i PI 7Q c 3 < 1`.`i VL,-. iV*. V, *, `.-.VsW-.v. V. V-..\\ s.%\ 'v V" `.'`'`VsVn"sNNV-.',sSWsV^.V.V-!v.V\ Vs\Vs\N^N\V^\NV^V^\\\\V--\\\y- ,'v- ', \\ \S1 .^VZvsSWSV'n vs *sV\\WV>W\ '\n]I WvVswssji ';v:| m G 3w3 HSI a M 33 oM 5 M 1-3 M 33 cn c 3` cO o o(O <cCooO o to to 00 DU 040280 LENGTH rniriiif - SI NUMBER OF FIBERS N Cm O O 0 O o 1 o c 3 'i '> V \ > N *1 s \ > . . * ".. ^ - ', * t C A\\\N\VSV*\\VA\V-*\\Nl 3 V* s .Vi. s.O.'.>'0>...''sr,-.\`W, \ \ns\\v*v*j SSSK'-'SS'V'S'n SS' '\\'S hW^Vk'* i--1 o. c 3 o __ o c 3 v8-Z9b HTH O' o on o CO co U oCUO ccCooO kMC>O DU 040281 Figure 3 - Workplace Protection Factors for 3M 8710 Respirator DUP 0949990.230 1.00 4.64 21.54 100.00 464.16 2154.44 10000.00 WPF Geometric Mean: 310 Geometric Standard Deviation: 5.3 Best Estimate of 5th Percentile: 20 Data: 7.4, 15, 61, 110, 110, 180, 200, 310, 400, 420, 430, 1000, 1000, 1100, 1500, 1600, 1800, 3200 HLR 462-84 ` - 16 - DU 040282 Figure 4 - Workplace Protection Factors for 3M 9910 Respirator / V u u p 0949990.231 10.00 31.62 100.00 316.23 WPF 1000.00 3162.28 10000.00' Geometric Mean: 580 Geometric Standard Deviation: 4.2 Best Estimate of 5th Percentile: 55 Data: 94, 110, 150, 150, 170, 280, 550, 630, 710, 1300, 2400, 3000, 3700, 5600 HLR 462-84 - 17 - Du 040283 Figure 5 - Workplace Protection Factors "IK for AO R1050 Respirator Cumulative Distribution: (Lognormal) -< H -- f-- ~ 0 3 > C D O J 3 T ) DUP 0949990.232 1.00 4.64 21.54 100.00 WPF Geometric Mean: 52 Geometric Standard Deviation: 4.2 Best Estimate of 5th Percentile: 5 Data: 9.7, 26, 28, 38, 52, 75, 970 HLR 462-84 - 18 - 464.16 2154.44 10000.00 DU 040284 Figure 6 - Workplace Protection Factors for Survivair 2000 and MSA Comfo Halfmask Respirators with Dust, Fume and Mist Filters Cumulative Distribution: (Lognormal) -< H -- r~ -- CO 00 O 30 "0> DUP 0949990.233 Geometric Mean: 240 Geometric Standard Deviation: 6.3 Best Estimate of 5th Percentile: 12 Data: 15, 24, 45, 46, 47, 74, 88, 140, 190, 370, 480, 1000, 1100, 1100, 1800, 4100, 4200 HLR 46 2-84 - 19 - ` DU 040285 rigure ( - workplace Protection Factors for Survivair 2000 and MSA Comfo Halfmask Respirators with High Efficiency Filters Cumulative Distribution: (Lognormal) DUP 0949990.234 Q -O C O C Q C C Q -- -J -- Geometric Mean: 94 Geometric Standard Deviation: 3.0 Best Estimate of 5th Percentile: 16 Data: 12, 28, 32, 42, 65, 85, 110, 120, 140, 160, 160, 220, 220, 780, 7900* HLR 462-84 * Removed from plot analysis, as an outlier. - 20 - DU 040286 Figure 8 - Workplace Protection Factors for North 7700 Halfmask Respirators * with High Efficiency Filters Cumulative Distribution: (Lognormal) DUP 0949990.235 WPF Geometric Mean: 250 Geometric Standard Deviation: 6.9 Best Estimate of 5th Percentile: 11 Data: 12, 20, 36, 60, 74, 110, 260, 350, 400, 1000, 1900, 2000,2400,3100 HLR 462-84 - 21 - DU 040287