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FILE NAME: Flooring (FLR) DATE: 2003 DOC#: FLR020 DOCUMENT DESCRIPTION: Journal Article - Asbestos Release During Removal of Resilient Floor Covering Materials by Recommended Work Practices of the Resilient Floor Covering Institute r , Applied Occupational and Environmental Hygiene Volume 18(6): 466-478,2003 Copyright 2003 Applied Industrial Hygiene 1047-322X703 $12.00+ .00 DOI: 10.1080/10473220390209530 I AsbestosRelease During Removal of Resilient Floor Covering Materials by Recommended Work Practices of the Resilient Floor Covering Institute Marion Glenn Williams, Jr. and Robert N. Crossman, Jr. The University o f Texas Health Center at Tyler, Tyler, Texas The release of asbestos during m aintenance and removal of resilient floor covering is of concern to health profession als and many regulators. This study assesses the asbestos levels observed during removal of resilient floor covering products using the "Recommended Work Practices" (1995) o f the Resilient Floor Covering Institute or other methods re quiring containment (Controls). The 1995 "work practices" require wet removal or dry heat removal but do not require the use of respirators. Wet removals o f sheet vinyl/separated backing, 12" x 12" vinyl asbestos tile/m astic, and 9" x 9" asphalt tiles/m astic were conducted and the air was sam pled during each procedure. Settled dust samples were col lected at the sites of RFCI square tile removal and pieces of each type of tile were broken in a mini-enclosure to eval uate asbestos em issions. Analyses o f the air samples col lected during the removals showed that the RFCI meth ods did not produce asbestos counts significantly different from the Control methods requiring containment. Only a sm all number (0.7%) of fibers and structures, counted and measured by Analytical Transmission Electron Microscopy, would have been counted using the rules for Phase Con trast Microscopy in the 7400 method specified by Occupa tional Safety and Health Adm inistration regulations. This indicates workers in sim ilar situations without respirators are likely to have unknown exposure levels. A high per centage o f these fibers and structures are 5 micrometers or less in length, sm aller than 0.5 micrometer in diame ter, and are easily inhaled. The RFCI air sample and set tled dust data may cause regulators to consider requiring respiratory protection, cleanup procedures, and methods to control asbestos migration. Other areas that might be ad dressed are clearance levels and their measurement, removal area size, bulk sample analysis by transmission electron mi croscopy if polarized light microscopy reports less than 1 percent asbestos, better worker exposure evaluation, and supervisor/worker training in accordance with the Model Accreditation Plan. K eyw ords Asbestos, Floor Covering, Abatement, RFCI Methods, Electron Microscopy, Phase Contrast Microscopy The possibility of the inhalation of asbestos fibers, during and subsequent to the removal of floor covering materials, is one of the major concerns of environmental consultants, pro fessional engineers, certified industrial hygienists, researchers, occupational medicine physicians, workers, and, most impor tantly, regulators. All states have an agency charged with pro tecting the health of their citizens by adopting federal standards as a minimum. Their standards may be more stringent, except for rules directly protecting workers unless the state is an OSHA contract state. The OSHA Asbestos Exposure in Construction Regulation 29 CFR 1926.1101^ is based on the types of mate rials and the nature of the work rather than the operation being conducted. The asbestos permissible exposure limit (PEL) was reduced to 0.1 f/cc for an 8-hour time weighted average (TWA) and the short-term excursion limit, re-designated excursion limit (EL), is 1 f/cc for a 30 minute TWA, The concept of specific work practices to be used with cer tain types of materials was introduced. One of these specific provisions was resilient floor covering, which is addressed as Class n work. Any resilient floor covering material installed in 1980 or earlier is defined as presumed asbestos contain ing material (PACM) and is identified as asbestos containing material (ACM) subject to sampling and analysis by techni cally feasible means to establish that the material in question does not contain greater than 1 percent asbestos. The analy sis is to be by the polarized light microscopy (PLM) protocol of the National Voluntary Laboratory Accreditation Program (NVLAP), which is administered by the National Institutes of Science and Technology (NIST). This OSHA regulation1' 1spec ifies that resilient floor materials are to be removed intact where 466 ASBESTOS RELEASE DURING REMOVAL OF RESILIENT FLOOR COVERING MATERIALS 467 possible, regulated areas are to be established and it also al lows the use of a negative exposure assessment based on per sonal sample data from projects "closely resembling the current project." Sheet vinyl floor covering does not contain asbestos in the walk surface but the backing frequently is asbestos felt (paper) and contains in our experience 40 percent to 75 percent asbestos. The asbestos content of square tiles is usually in the range of 8-50 percent. The asbestos is mixed throughout the tile and thus is subject to wear and abrasion during normal use/3-7' Stripping and buffing operations have been documented as producing air borne fibers/4,8 OSHA regulations11' specify the use of a low-speed buffer (<300 RPM) and the least abrasive pad. It is difficult to determine asbestos content by PLM112-17' in square asphalt and viny1asbestos floor tiles. In a policy guidance document118' the EPA has stated that in the event flooring ma terials are reported at 1 percent or less by PLM112-14' analysis, the asbestos content should be determined by transmission elec tron microscopy bulk analyses methods/12-14' The NVLAP accreditation program requires accredited laboratories to insert a disclaimer in the laboratory report stating that "PLM is not a valid method for determining asbestos content in floor cov eting materials and if the analysis is reported at 1 percent or less, analytical transmission electron microscopy (ATEM) bulk methods should be used." The EPA has published an ATEM anal ysis method02-14) for floor tiles and other small fiber-containing materials. The asbestos used in flooring materials is Grade 7-- Shorts and Floats. The dimensions of this material are very small and may not be resolvable by the PLM microscope. Also, fibers may be obscured by the matrix. It is easy to understand why analy sis of floor tiles is very difficult by PLM when you investigate the manufacturing methods and the specifications13-8-16' 17' for floor covering materials. The common procedure for the man ufacture of resilient floor covering is to use Banbury mixers15' that are heated. Raw materials are mixed by a tumbling action. The specifications generally call for approximately 25 percent asbestos. This may be more or less in some cases. Shorts and Floats are the cheapest asbestos materials. A marketing person at an asbestos company advised that Grade 7 is no longer sold and in fact is buried by the m ill/19' The asbestos, which is added to the flooring materials, is serving as a binder rather than im proving resistance to wear or providing friction. A t the time of the mixing, different materials may be added and the color and patterns are established. fiber used by U.S. OSHA (29 CFR 1926.1101 [b])/1' The end result is the PEL of 0.1 f/cc 8 hr TWA is seldom exceeded in resilient flooring removals. In contrast, clearance samples un der the Asbestos Hazard Emergency Response Act (AHERA) rules122' are collected on smaller-pored filters (0.45 /xm or 0.4 /xm) and are analyzed by the AHERA ATEM protocol count ing structures >0.5 /xm long to 5 /m long and >5 /xm long with a >5:1 aspect ratio. Many studies123-28' confirm asbestos exposure causes dis ease. The premise129' that only long fibers (>10 /xm) are going to cause asbestos disease becomes very difficult to rationalize in fight of the many research studies that find that a preponderance of fibers at autopsy left in lung tissue, pleural plaques, and lymph nodes of persons who have occupational exposure to asbestos are shorter than 5 /xm in length/23-29-33' OSHA was advised by the Health Effects Institute134' in 1993 that personal expo sure analysis by the NIOSH 7400 protocol120' was not a valid way to evaluate a person's exposure and a recommendation that at least some samples should be analyzed by AHERA ATEM protocols122' was made. The Asbestos Hazard Emergency Response Act Regulations. 40 CFR 763 Subpart E /22' require public schools to inspect for friable and non-friable ACM. Areas having settled dust from delamination are required to be cleaned to abate potential ex posure from occupant activities that may re-entrain settled dust, allowing it to be inhaled/35-36' The area where resilient floor covering is removed by RFCI methods137'38) is required by set tlement agreement139' with OSHA to be isolated from other areas. It is also common to find reports and research papers that state analyses were by TEM but they do not specify the proto col used/40' There is an ATEM procedure for air samples using the protocol designated NIOSH 7402/41' This TEM protocol counts asbestos and non-asbestos fibers that would be counted with a light microscope. The difference in the protocols is use of X-ray Energy Dispersion Spectroscopy (XEDS) and Selected Area Electron Diffraction (SAED) to identify those fibers meet ing the asbestos count criteria. The "percent asbestos" in the sample is then used to reduce the PCM count. The obvious problem with this method is that it underreports the amount of asbestos in the samples because it ignores all fibers <5 /xm and all those fibers longer than 5 /xm but less than 0.25 /xm in diameter. The fact that the dimensions of the asbestos fibers used in the manufacturing of flooring are so small accounts for the very low personal exposures based on analyses of flooring worker air samples by phase contrast microscopy (PCM) in accordance with the NIOSH 7400 protocol/20' Many ultrafine fibers are not counted19'21' due to the resolution (0.2-0.25 xm) of the phase contrast microscope and due to the count protocol, which pro vides that only fibers longer than 5 /xm with a 3:1 or greater length-to-width ratio will be counted. This is the definition of a STUDY DESIGN The procedures to be investigated are those for the removal of sheet vinyl, vinyl or asphalt floor tiles, and cutback mastic using amended water or an adhesive removal product allowed in "Recommended Work Practices for the Removal of Resilient Floor Coverings."137'38' fir this study Abatix 007 was the removal product used. An additional area at each site was designated for control removal" utilizing the aggressive methods normally used in removals by abatement contractors. In each case the 468 M. G WILLIAMS, JR. a n d R. N. CROSSMAN, JR goal was to produce a clean flat surface ready to accept new flooring. Some residual mastic always remained in the pores of the concrete sub-floor. The following^general criteriaTM were established for all field investigations during the study: 1. Locations for the investigative procedures were evaluated by a licensed asbestos inspector. No sites were used that had any friable ACM or damaged ACM present in the area. 2. The six removal workers were EPA Model Accredita tion Plan (MAP)(42'43) accredited and were experienced in asbestos abatement. The same workers were used at all sites. 3. Each site was cleaned by high efficiency particulate air (HEPA) vacuum and/or wet wiping. Five baseline sam ples were collected prior to. initiating any preparation work. Sample volumes were between 560 to 1560 liters to avoid overloading. The baseline air samples were collected and analyzed by PCM, NIOSH 7400, Is sue 2, A counting rules,(20) and ATEM Yamate Level n ,(44) and in each location revealed a lack of asbestos contamination. 4. Three bulk samples of sheet vinyl or floor tile/mastic per site were analyzed by PLM(2'12'14) and the Chatfield ATEM Method.TM 5. Each work site had critical barriers installed and was un der a differential pressure of -0.02 inches water column. All sites had fuE inverted containment consisting of a single layer of 4 mm polyethylene on the walls and ceil ing. During each specific RFCI procedure, the work area within the negative pressure enclosure was sealed using polyethylene partitions sealed to the floor and ceiling and polyethylene double flap openings taped closed so there was no air circulation inside. The air flow was checked using smoke tubes, and there was no detectable flow ob served. Each of the control investigations was conducted with four air changes per hour in the work area. AU lo cations had decontamination facilities. 6. Five area air samples were collected in the work area involved during each procedure. Four samplers were lo cated about four feet from the comers of the room and a fifth was placed in the center of the room. Sample vol umes in each of the work areas varied due to the vi sual loading of the filters and/or the time required for the procedures to be conducted. AU air samples were coEected on 0.45 /xm mixed ceEulose ester (MCE) fil ters in 25 mm conducting cassettes with 50 mm ex tension cowls at a flow rate of 1 to less than 10 Eters per minute. AE flow rates for air samples were mea sured at the start and at the completion of the sampling period using an Asbestos Analytic Rotameter that was calibrated prior to this project using a Gilibrator elec tronic calibrator as the primary standard. AE air sam ples were analyzed^by NIOSH 7400 Method, Issue 2. Counting Rules A,(20) and by ATEM, Yamate Level II Method.(44) . 7. Outside air samples were taken at negative air unit dis charges and areas outside the containment and were an alyzed by both PCM and ATEM using the procedures cited in item 3 above. Asbestos contamination was not detected. 8. Following the completion of the procedures at each work site, each area was cleaned by HEPA vacuum and wet wiping. Air samples for clearance analysis were collected by aggressive methods and were analyzed by ATEM in accordance with 40 CFR 763 Subpart E, Appendix AC22) at an NVLAP-accredited laboratory. 9. After clearance was achieved, aU remaining polyethyl ene was removed and disposed of as ACM and the areas were made available for re-occupancy foEowing final cleaning. 10. The Texas Department of Health is not an OSHA enforce ment agency and personal samples were not a part of the study. Personal samples were coEected by the workers' employer and no levels greater than the PEL or EL were detected. The removal of sheet vinyl (Figure 1) in a hospital home medical equipment store was conducted in Areas 1 and 2 in accordance with the RFC! work practices/37) The workers slit the vinyl into 8" strips and attempted to roU it while cutting, with short-handled scrapers, at the wet nip line where it separated from the mastic and asbestos felt backing. This backing was then removed from the floor using more amended water and shorthandled scrapers. The vinyl strips and pieces were placed in disposal bags. Scrapings were coEected with wet wipes and a wet HEPA vacuum. The vinyl broke up readEy because it was brittle and weE adhered to the floor. The use of short-handled scrapers required the workers to be on their knees or bent over while they worked and thus close to the asbestos emission sources. The workers did not walk on the concrete sub-floor until it was dried, HEPA vacuumed again, and wet wiped (see step 8 above). Area 3 was the control area where more aggressive measures with long-handled scrapers and amended water were used to remove the vinyl, felt, and mastic at the same time. The area was cleaned as above. Areas 1,2, and 3 were approximately 130 ft2 each. The 12" x 12" vinyl tiles (Figure 2) were located in a commer cial building. They were removed in Areas 1 and 2 according to RFCI methods7) using amended water and short-handled scrapers. The workers again had to work on their knees as they tried to remove the trie in as near an intact state as possible. Area 3 was the control area where the tiles and mastic were removed together by long-handled scrapers and amended water. The tile fragments and scrapings in each area were picked up and the ar eas were cleaned with wet HEPA vacuums. They were allowed to dry, HEPA vacuumed again, and wet wiped until clean. Area 1 ASBESTOS RELEASE DURING REMOVAL OF RESILIENT FLOOR COVERING MATERIALS 469 FIGURE 1 Sheet vinyl removal--RFCI method. (Hospital home medical equipment store, Area 1). was approximately 240 ft2, Area 2 was 200 ft2, and Area 3 was 700 ft2. The 9" x 9" asphalt tiles (Figure 3) were in a high school cafeteria. The tiles in Areas 1 and 2 were removed wet with amended water and short-handled scrapers using RFCI methods/375The mastic in Area 1 was removed wet with Abatix 007 solvent and the resultant slurry was picked up with wipe rags. The cleaning was completed using a HEPA vacuum and additional wiping with rags and clear water. The mastic in Area 2 was removed with amended water. Area 3 was the control area where long-handled scrapers and the more aggressive measures described for Area 3 of the commercial building were used. Areas 1 and 2 were each approximately 150 ft2 and Area 3 was 200 ft2. Settled dust samples05 were collected from 1 ft2 areas ap proximately 16 h after the removal of 12" x 12" tiles and mastic in RFCI Area 1 of the commercial building and just prior to final cleaning. Filtered de-ionized water was used to suspend the dust on two horizontal surfaces and a micro-vacuum(455 was used to collect dust on a dry vertical surface. The liquid sam ples were drawn into flasks using personal pumps. The micro vacuum collection^455 was on a 0.45 zm pore size MCE fil ter in a conducting lab cassette with a Tygon tubing exten sion cut at 45 connected to the inlet opening in the end cap. The same procedures were conducted in RFCI Area 2 in the high school cafeteria following removal of 9" x 9" tile and mastic. An additional investigation was conducted inside a 4 ft x 3 ft x 4 ft mini-enclosure to determine the extent of asbestos emission due to tile breakage. Square tiles from each of the sites used in the study were placed on a slightly raised rack and broken with a single blow from an automobile body repair hammer. The tile pieces were allowed to remain without distur bance during the breaking. There was no movement of the tiles to cause abrasion, and there was no mastic adherent to these tiles. Closed loop air samples (510-601L) were taken inside the enclosure during the entire process. After completion, the air in the mini-enclosure was exchanged and the entire enclosure was HEPA vacuumed and wet wiped before the next samples were broken. ASBESTOS RELEASE DURING REMOVAL OF RESILIENT FLOOR COVERING MATERIALS 471 ANALYTICAL PROCEDURES Bulk Sample Analysis Bulk sample* were analyzed by both PLM and ATEM. The PLM procedure is described in 40 CFR 763, Subpart F, Appendix A.(22 The ATEM analyses were performed accord ing to Chatfield/130PLM results are reported as area percent and ATEM results as weight percent. Phase Contrast Microscopy Phase contrast microscopy following NIOSH 7400, Issue 2(20) was used to analyze portions of the 0.45 /xm MCE filters for later comparison with ATEM results. One-fourth of each filter was analyzed at 400x and fibers longer than 5 /im with aspect ratios equal to or greater than three were counted us ing the NIOSH 7400 "A" rules/201 Results are reported as fibers per cc. Analytical Transmission Electron Microscopy ATEM counts were obtained on the above filters using the Yamate Level II protocol/440In brief, portions of the filters were collapsed on glass slides with acetone vapor and plasma etched until 10 percent of the surface was removed. They were car bon coated in a vacuum and small squares were placed on cal ibrated 100 mesh grids. The MCE plastic was removed in an acetone condensation washer. The samples were examined at a magnification of 16,000x or 20,000x for asbestos structures, most of which consisted of multiple asbestos fibers counted as a single structure (Figures 4a through 4d). One 100-mesh grid square was analyzed on each of three grids. To be counted, a structure had to be or have an asbestos fiber with a 5 to 1 or greater aspect ratio and be at least 0.5 gm long or greater. Se lected area electron diffraction (SAED) and X-ray energy dis persive spectroscopy (XEDS) were used to confirm all asbestos and non-asbestos structures. The first 33 structures from each grid were measured and categorized as fibers, bundles, clusters, or matrices according to AHERA/220 The remainder were cat egorized morphologically and recorded as asbestos structures greater than or equal to 0.5 /xm to less than 5 /xm, or greater than or equal to 5 /xm in length. The data were made to conform to the AHERA counting rules(22) and were reported using the AHERA guidelines/220 The AHERA protocol^220 was used for collection of all clearance samples. FIGURE 4a Chrysotile fiber. (12" x 12" vinyl asbestos tile removal by RECI method; TEM, bar equals 1 /xm). 472 M. G. WILLIAMS, JR AND R. N. CROSSMAN, JR Settled Dust Samples These samples were collected in one of two ways. In the first case, water pre-filtered through 0.2 //.m pores was used to thoroughly resuspend settled abatement dust on horizontal 1 ft2 areas. Aliquots were removed, filtered through 0.45 fj,m MCE filters, dried, and prepared for ATEM by the direct carbon extraction replica technique described above. The second case involved the removal of settled dust from 1 ft2, vertical surfaces TABLE I Sheet vinyl removal-- Hospital home medical equipment store bulk sample analysis Description Sheet vinyl, light green # of samples 3 PLM Vinyl layer: ND Backing: 60-65% Air sample analysis Location Area 1 RFCI Area 2 RFC! Area 3 control # of samples 5 5 5 Sample volume (liters) 1200 750 585 PCM f/cc 0.011-0.029 0.024-0.034 0.024-0.031 ATEM total s/cc 0.806-0.860 0.562-0.697 0.675-0.902 ATEM > 0.5 to <5 s/cc 0.437-0.584 0.284-0.426 0.204-0.393 ATEM ND 70-80% ATEM > 5 s/cc 0.254-0.369 0.264-0.291 0.482-0.573 ASBESTOS RELEASE DURING REMOVAL OF RESILIENT FLOOR COVERING MATERIALS 473 FIGURE 4c Chiysotile cluster. (Sheet vinyl removal by RFCI method; TEM, bar equals 1 pm). using the ASTM D5755.95 micro-vacuum method.(35-36) The 0.45 MCE filters were prepared for ATEM analysis as above. The data were reported as structures per square foot. Statistical Analysis Data were tested for significant differences, after square root transformation, with the t test for independent samples. RESULTS Table I tabulates the data for the sheet vinyl investigation. The PLM bulk analysis reported the vinyl layer as none detected (ND) and the felt backing as 60-65 percent chrysotile. The bulk analysis by ATEM(13) reported the vinyl layer as none detected and the felt backing as 70-80 percent chrysotile. The labora tory results of fiber levels by PCM for removal of sheet vinyl TABLE II 12" x 12" vinyl asbestos tile removal-- Commercial building bulk sample analysis Description # of samples PLM TEM 12" x 12" tan tile Black mastic 3 Air sample analysis ND 5-8% 4-8% Location # of samples Sample volume (liters) PCM f/cc ATEM total s/cc ATEM >0.5 to <5 s/cc ATEM > 5 s/cc Area 1 5 RFCI Area 2 5 RFCI Area 3 5 control 1560 <0.003-0.005 0.035-0.085 0.023-0.294 0.012-0.036 840 <0.006-0.009 0.066-0.236 0.035-0.147 0.031-0.089 1480 0.005-0.012 0.081-0.127 0.051-0.083 0.025-0.044 474 M. G. WILLIAMS, JR AND R. N. CROSSMAN, JR FIGURE 4d Chrysotile matrix. (Sheet vinyl removal by RFCI method; TEM, bar equals 1 jum). using RFCI Work Practices(3/) ranged from 0.011 to 0.048 fibers per cc. Inside the control area the range was from 0.024 to 0.031 fibers per cc. None of these samples exceeded the Ex cursion Limifi15or Permissible Exposure Limit.(lj The range of asbestos structures per cc reported by (ATEM) Yamate Level II M e th o d ^ was 0.562 to 1.002 structures per cc for the RFCI Work Practices.(37) The range inside the control area was re ported at0.675to0.902 asbestos structures per cc. Only7 percent Description 9" x 9" beige tile Black mastic Location Area 1 RFCI Area 2 RFCI Area 3 control # of samples 5 5 4 TABLEm Asphalt tile removal--High school cafeteria bulk sample analysis # of samples 3 Air sample analysis PLM 1-3% 7-10% Sample volume (liters) 560 PCM f/cc 0.011-0.014 ATEM total s/cc 0.099-0.355 ATEM >0.5 to <5 s/cc 0.071-0.294 850 0.008-0.012 0.138-0.387 0.104-0.322 735 0.011-0.015 0.240-0.332 0.148-0.174 TEM 12-19% ATEM > 5 s/cc 0.028-0.061 0.034-0.065 0.092-0.179 ASBESTOS RELEASE DURING REMOVAL OF RESILIENT FLOOR COVERING MATERIALS 475 Location 1 # of samples Area 1 5 Abatix 007 Area 2 5 Amend, water TABLEIV RFCI mastic removal-- High school cafeteria Sample volume (liters) 567 PCM f/cc 0.048-0.075 ATEM total s/cc 1.319-1.749 ATEM >0.5 to <5 s/cc 0.859-0.120 750 0.011-0.018 0.094-0.184 0.083-0.161 ATEM > 5 s/cc 0.460-0.752 0.017-0.061 ... of the fibers and bundles found and measured by ATEM'445 in the RFCI Work Practices'375 areas were counted applying the NIOSH 7400 PCM(20) rules and resolution to the ATEM data and only 5 percent were counted in the control area. These data indicated the PCM method of analysis greatly underestimated the level of actual asbestos fibers. Table II tabulates laboratory results for the removal of 12" x 12" vinyl asbestos tile by RFCI and Control methods. The bulk PLM Analysis of the tile was reported none detected and the mastic was 5-8 percent chrysotile. ATEM Bulk Analysis re ported the tile as 4-8 percent chrysotile. The range of fibers reported by PCM for the RFCI removal in the two areas was less than 0.003 to 0.009 fibers per cc. The PEL and EL were not exceeded. The ATEM results for these areas were 0.035 to 0.236 asbestos structures per cc for the RFCI removal. The results for the control removal were 0.005 to 0.012 fibers per cc by PCM and 0.081 to 0.127 asbestos structures per cc by ATEM. Only 2.5 percent of the fibers and bundles found and measured by ATEM in the RFCI areas were counted applying the PCM rales to the ATEM data and only 2 percent of those in the control area were counted. Again, PCM greatly underestimated the asbestos fiber level due to the count protocol and resolution. Table III presents results of the investigation involving 9" x 9" asphalt tiles and mastic. The bulk analysis of tile by PLM re ported 1-3 percent and the mastic was 7-10 percent. The ATEM bulk analysis reported the tile at 12-19 percent chrysotile. The range of fibers reported by PCM for the two RFCI removal ar eas was 0.008 to 0.014 fibers per cc. The PEL and EL were not exceeded. The ATEM range was 0.099 to 0.387 structures per cc for RFCI removal. The PCM level reported for the control method was 0.011 to 0.015 fibers per cc and the ATEM result was 0.240 to 0.332 asbestos structures per cc. Two and one-half (2 1/2) percent of the asbestos fibers and bundles counted and measured by ATEM were counted by applying PCM rules to the ATEM data in the RFCI area and none were counted in the control area. Table IV presents mastic removal data obtained after the 9" x 9" tile removal. In mastic removal Area 1, using the mastic remover Abatix 007, results were 0.048 to 0.075 f/cc by PCM and 1.319 to 1.749 asbestos structures per cc by ATEM. One-half of one (0.5) percent of the fibers and bundles counted and measured by ATEM were counted by applying PCM rules to the ATEM data during m astic rem oval. A g a in , it w as seen that PCM greatly underestimated the actual asbestos fiber level due to the count protocol. The fiber levels reported by PCM analysis during removal of mastic in Area 2 by amended water were 0.011 to 0.018 f/cc and 0.094 to 0.184 asbestos structures per cc by ATEM. The levels by PCM were lower by a factor of four when using amended water compared to Abatix 007 mastic remover and lower by a factor of eleven with ATEM. Table V tabulates the results of settled dust samples reported as structures per square foot by ATEM analysis.'445 The level of asbestos on the horizontal surfaces ranged from 14 million to 25 million structures per square foot. The level on the ver tical surfaces was from <1100 to 4800 structures per square foot. These data indicated asbestos dust settled more readily on horizontal surfaces than on vertical surfaces. It is possible that the asbestos sampling on the vertical surfaces, using the micro vacuum method, was incomplete because other fibers may have been held on the surface by static charges or lockdown. The results of the ATEM analyses of air samples collected inside a mini-enclosure while tiles were broken by striking a single blow with an automobile body hammer were as follows: Both 12" x 12" and 9" x 9" tiles were tested. In each case the tiles were allowed to lie and were not further disturbed. The asbestos released, measured by ATEM, was at or less than the detection limit (<0.0058 str/cc). This probably was due in part to the binding of the matrix and the fact that no disturbance of the pieces occurred after breaking. TABLE V ATEM settled dust results--Horizontal surfaces, water collection Description Sample Str/ft2, (millions) Commercial building, TW--01 25 post-RFCI TW--02 20 High school cafeteria, NW-- 1A 23 post-RFCI NW-- IB 14 Vertical surfaces, micro-vacuum collection Commercial building, post-RFCI TV-- 01 -- <1100 --- High school cafeteria, NV-- 301 4800 post-RFCI -- -- 476 M. G- WILLIAMS, JR- AND R N. CROSSMAN, JR C O N C LU S IO N The following information was obtained from the study. PCM and ATEM air analyses (Tables I, II, and HI) revealed asbestos emissions produced by the RFCI and Control methods did not significantly differ from each other at any of the three locations in the study. A possible reason for this is that the materials were firmly adhered to the sub-floor, unlike those more recently installed. Another important finding for both methods was that the ATEM counts for total asbestos structures per cc averaged 22 times greater than the PCM fiber counts on the same filters (Tables I--IV). The ATEM asbestos concentrations obtained during RFCI mastic removal with a commercial mastic remover averaged 11 times those measured during the RFCI removal with amended water (Table IV). Considerable amounts of asbestos dust settled on exposed surfaces during the RFCI tile removal in both locations (Table V). Finally, the PLM bulk sample analyses underestimated the amounts of asbestos in the flooring materials (Tables I-m ). The RFCI method146' used in our original study015 produced higher counts than the RFCI methods075 in the current study because the 1990 RFCI procedures^465 did not require the use of amended water. Since the RFCI procedures075 cited in the agreed judgment095 still did not require respiratory protection for the workers or cleanup standards for the work areas or clear ance samples, anyone in the areas during either study without a respirator would have inhaled asbestos fibers or structures of respirable dimensions. The elevated asbestos levels measured during the RFCI and Control sheet vinyl/mastic removals were probably caused by the following: 1. The brittle vinyl broke easily everywhere and was well adhered in the heavy traffic areas because it had been installed for a number of years. 2. Additional effort was often required to remove the residual asbestos felt and mastic from the concrete sub-floor. The cause of elevated asbestos levels during the removal of square tile/mastic was probably due to one or all of the following: 1. Removal by RFCI or controlled methods resulted in bro ken pieces of tile abrading each other as they were pushed together by the removal tool. 2. The mastic was abraded as the tile was removed and was further abraded by scraping as other tiles were removed. 3. hi those cases where the tile was firmly attached, more aggressive use of the scraper was required to remove these tiles or the pieces of tile from the floor. The fact that the simple breaking of tiles in the mini-enclosure did not produce enough airborne fibers to be detected by ATEM supports the idea that a major portion of the asbestos emissions were caused by abrasion between tile/mastic fragments and/or by the scrapers. The higher levels of fibers seen during the re moval of mastic using organic mastic remover were probably due to the action of the solvent on the binders that were holding the asbestos. , Asbestos structures settled in the work areas (Table V) and, if not contained and cleaned up, would have been subject to re-entrainment by occupant activities. In order to address the protection of human health and the environment the follow ing suggestions are prudent based on the asbestos levels gener ated during all of these procedures by well-trained, experienced workers. 1. It is important to insure that all employers who remove "intact" flooring materials using RFCI work practices no tify the employers of employees who will be working in adjacent areas during the removal and that they isolate the work area by an impermeable barrier, which may include a wall, closed door, or window as required by law. (See paragraph 6, page 9 of Settlement Agreement in the U.S. Fifth Circuit Court of Appeals, June 1,1995, Azrock In dustries, Inc., et al. versus Occupational Safety and Health Administration, U.S. Department of Labor).095 2. Require proper cleanup by HEPA vacuum/wet wiping within the removal area and the contiguous areas, if not separated. 3. Establish clearance levels and sample collection methods for all removals by RFCI methods in public, commercial, and industrial buildings. The sample collection should re quire aggressive methods to be used. The clearance level should be specified as less than 0.005 structures per cc for each sample and all samples collected must be analyzed by the AHERA ATEM protocol025 and must be reported. It is recommended that larger volumes be collected and larger filter areas be quantified to insure greater accuracy. The recommended minimum sample volume is 1250 liters. The minimum number of samples for clearance should be one for each 500 square feet. Each sample should be collected on 0.45 /xm MCE filters in 25 mm diameter con ducting cassettes with a 50 mm extension cowl at a flow rate of 1 to <10 Lpm. AHERA025 regulation clearance standards already apply to public schools. 4. For removals prior to demolition, a clearance level of 0.01 structures per cc by AHERA ATEM protocol025 is recommended. 5. Regulations should be revised to require all flooring mate rials to be analyzed by the ATEM Bulk Sample method035 if samples analyzed by PLM are reported as 1 percent or less asbestos content. An assumption of asbestos content greater than 1percent is allowed by all federal regulations. An examination of the PCM and ATEM air sample data from the same filters readily reveals the problems associated with us ing PCM to estimate asbestos air concentrations in these removal situations. These problems are: (1) all fibers must be counted by PCM, non-asbestos and asbestos, resulting in non-specificity and (2) a very high percentage of the asbestos present is not seen or must be ignored because of the counting rules. The Health ASBESTOS RELEASE DURING REMOVAL OF RESILIENT FLOOR COVERING MATERIALS Effects In stitu te ^ realized these problems with PCM in 1993 when they advised OSHA that at least some samples should be analyzed by''the AHERA ATEM protocol.0 The authors definitely agreewith this position. There is an undetermined quantity of asbestos-containing flooring materials presently installed in buildings throughout the United States. There is no prevailing regulation(47) that pro hibits the manufacture and/or importation into the United States of asbestos-containing flooring materials. Most, if not all, do mestic manufacturers of flooring materials do not put asbestos in their products at this time. However, with one exception, there is no regulation that prohibits the installation of ACM flooring materials in any facility in the United States. Texas has recently passed a law prohibiting the replacement of asbestos-containing material after removal in public or com mercial buildings with any other ACM.(48) Some school districts have installed new flooring material and wrongly assumed that it would not contain asbestos when, in fact, it did. Another concern is the residential area. The same ACM ma terials are found in single-family dwellings and apartment build ings. There is no way to estimate the number of residences that have flooring materials containing asbestos at greater than 1per cent. These are locations where flooring materials are routinely removed without any type of control because as a single family dwelling there are no regulations with regard to accreditation of personnel involved or disposal of the asbestos-containing ma terial. 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