Document z2eKdLB6XnqZaka615N5mR37

FILE NAME: Flooring (FLR) DATE: 1996 May DOC#: FLR034 DOCUMENT DESCRIPTION: Journal Article - Quantification of Fiber Releases for Various Floor Tile Removal Methods [More Pages] Quantification o f Fiber Releases for Various Floor Tile Removal Methods Robert N . Crossman, J r.,A M . Glenn Williams, Jr.,B Jerry Lauderdale,c Kathy Schosek,B and Ronald F. Dodson3 1 1o r/ f ^ U1parti'?nal Healftl Sciences' The University of Texas Health Center at Tyler Cn. TThhee Ullnnive9rshitry oyff TT exa's Hl kearl'tlhJ CVen5t7e0r9a:t tTDyl,eepr,0r1,m19en3t7oUf .CSe. "HBigiohlwgayy a2n7d1 EnTvyilreornmTXen7t5al70Li8e-nees, Division ot Occupational Health, Texas Department of Health, 1100 W. 49th St., Austin, TX 78756 The risk of human exposure from asbestos-containing material is directly related to the condition o f the material, custodial/mainte- nance activities, and the methods used to reduce the potential expo sure to workers, bystander employees, and occupants of the area containing the asbestos. Many consider floor tile to be nonfiiable, which is in accordance with the National Emission Standards for Hazardous Air Pollutants regulations, although there is some docu mentation o f fiber releases from deterioration o f such asbestos-con taining materials during polishing, removal, or routine walking, due to the friction generated by such activities. This study evaluates sev eral commonly used procedures for removal of floor tile and quanti fies the fibers released during those procedures using data obtained by analyses from phase contrast microscopy and analytical transmission electron microscopy. These data document that fibers are released when floor tile is broken and/or abraded during removal procedures. Fiber levels vary with the aggressiveness of the procedures. A con siderable percentage of the asbestos fibers identified by the analytical transmission electron microscopy methods specified in the Asbestos Hazard Emergency Response Act are below the size that can be detected by phase contrast microscopy and which are also the most easily respired due to their physical characteristics. C rossman, Jr., R.N.; WlllJAMS,JR., M .G.; Ia UDERDAIE,J.; ScHOSEK, K.; DODSON, R.F.: QUANTIFICATIONOF Fe ReiASES for Various Floor The Removal Methods, A po, O ccur Environ Hyg. 11(91:1113-1124; 1996. ' ' T he risk o f human exposures from asbestos-containing building materials is considered to be direedy related to the condition o f the material, degree o f friability o f the mate rial, the asbestos content (percent), and the fiber size distribu tion w ithin the product. An effective management strategy for reducing the potential o f exposure must therefore include a physical inspection made by an accredited inspector to evaluate factors such as air movement, accessibility, vibration, and po tential for disturbance based on the type o f material (surfacing, thermal, miscellaneous).'1,2) ' Floor tile, w hich is classified as miscellaneous material, poses a particular challenge for proper management since any asbes tos is often finely dispersed w ithin the matrix, and thus difficult to assess as to percentage by standard techniques using polar ized light microscopy (PLM). M any floor tiles do contain asbestos, usually chrysotile, at levels up to 25 percent, but which may be reported as 1 percent ot less by PLM analysis.(3_5>Therefore, asbestos fibers, because of their potentially thin diameters, require analytical transmission electron micros copy (ATEM) as the method o f choice for accurate quantita tion in air samples and some bulk materials.'6) This is partic ularly important in chrysotile-containing products where many fibrils below the limit of detection by light microscopy may become airborne and thus inhalable.'7) While it may be considered that the asbestos fibers in products such as floor tiles are bound and not easily released unless broken or crushed, Sebastien et al., found that even under normal conditions of weathering, asbestos fibers were released into the environ m e n t.'8) Although levels of asbestos in public buildings may usually be low, elevated levels of airborne asbestos can be expected when asbestos-containing material (ACM), including floor tile, is in poor condition or is disturbed by occupants and mainte nance activities.'9) The Environmental Protection Agency (EPA) has reported asbestos fiber release from floor tile spray buffing operations in 12 o f 17 schools in New Jersey.'10) The Occupational Safety and Health Administration (OSHA)'11) requires polishing of asbestos-containing floor tile to be con ducted using least abrasive pads and polishers operating at 300 rpm or less.'11) Limited numbers of other studies have been carried out to ascertain what fiber release occurs when asbestos-containing floor tiles are removed by procedures not utilizing negative pressure containment and wet methods as required under the Asbestos Hazard Emergency Response Act (AHERA)'12) for asbestos abatement in public schools. Unfortunately, these data are usually collected for personal exposure compliance pur poses and not as part of a protocol in a scientific project. The published data often fail to describe condition, age, type of material, asbestos type and content, sampling information (vol ume and collection rate), filter pore size, and analysis protocols. The EPA has published a guidance advisory'3) specifying that floor tile should be analyzed by ATEA1, if it is reported to contain 1 percent or less asbestos by PLM. The OSHA regu lation 1926.110113 places all floor tile installed in 1980 or earlier in the presumed ACM category, unless rebutted by a bulk sample analysis by a technically feasible method. How ever, a final rule to phase out distribution of vinyl asbestos tile (VAT) in the United States was declared invalid by the U.S. Court of Appeals in New Orleans; therefore, the manufacture, distribution, and importation of VAT are not restricted.'13) APPLOCCUP.ENVm.ON.HYG. 11(9) SEPTEMBER 1996 1047-322X/96/1109-1113$15.00/12 1996 AIH PII S1047-322X(96)00l72-0 1 1 1 3 1 1 1 4 R.N. Crossrnan et al APPL.OCCUP. ENVIRON.HYG. 11(9) SEPTEMBER. 1996 The issue of potential exposure from the removal o f floor tiles in public buildings can be addressed by either total con tainment procedures or through one o f several other proce dures, such as the suggested work practices published by the Resilient Floor Covering Institute (R FC I)/14) W hen federal or state regulations permit, selection o f the removal technique is left up to building owners or their consultants. The decision may be made on the perception that total containment pro cedures are the most costly, without considering the potential health risk and liability risk. Total containment controls emis sions and residue, while noncontainment may result in expo sure to workers during the project and to occupants through reentrainment by subsequent activities. The authors established a joint research investigation with the Texas Department o f Health, which was designed to assess fiber release during floor tile removal in public buildings by a series o f available procedures, monitored by phase contrast (light) microscopy (PCM) and ATEM. These data were quan tified to compare the merits of each method, as well as the level fibers detected by PCM versus ATEM in actual work place environments. The Texas Asbestos Health Protection Rules, September 1994, 295.36/15) provide an exemption from licensing and registration for persons removing resilient floor covering ma terials in public buildings, if those persons received training in an 8-hour course covering the elements in the document titled, Recommended Work Practices for the Removal of Resilient Floor Coverings, published by the RPCI in 1990/14) Methods Study Design The following general criteria were established for all field investigations during this study: 1. Locations for investigative procedures were evaluated by a licensed asbestos inspector to rule out the potential for asbestos contamination caused by friable and/or damaged ACM in the work areas. No sites were used which had any friable ACM or damaged ACM present in the area. 2. Each site was cleaned by high efficiency particulate air (HEPA) vacuum and/or wet wiping prior to the collec tion of baseline samples and the beginning of any work that was part of the test procedures. The baseline air samples were collected and analyzed by PCM (NIOSH 7400, Rev. 3,A rules) and A TEM /2'16' 3. Bulk samples of floor tile and mastic were analyzed bv PLM.07) 4. Bulk samples of floor tile were analyzed by ATEM via the Chatfield M ethod/181 5. Each work site had critical barriers installed and was under a differential pressure o f -0 .0 2 inches water column. Two o f the sites had polyethylene wall covering while the third site had full inverted containment consisting of a single layer o f 4 ml jpolyethylene on the walls and ceiling. (The type o f containment will be noted under specific proce dures.) All work sites had a minimum of four air changes per hour within the critical barriers. During each specific procedure, the work area within the negative pressure enclosure was sealed using double flap doors taped closed so there was no ai circulation by suction or discharge from negative air i lachines. The air flow was checked using smoke tubes and there was no detectable flow observed. The exci prion for this is the full AHERA(2procedure investiga ion, which was conducted with no restriction o f flow hrough the work area. All locations had decontaminatio i facilities/11,19'201 6. Three air samples vere collected in the work area in volved during each procedure. These were analyzed by PCM and ATEM. ' "he relative location in each area was the same. 7. Outside samples we e taken at negative air unit discharges and areas outside co itainment and were analyzed by both PCM and ATEM ising the procedures cited in item 2 above. 8. Following the com iletion of the procedures being eval uated, each area wa: cleaned by HEPA vacuum/wet wip ing and samples fbi clearance analysis were collected by aggressive methods. 21 These samples were also analyzed by PCM and ATEf 1. 9. After clearance was achieved, all remaining polyethylene was removed and di posed of as ACM and the areas were made available for i occupancy following final cleaning. 10. All area air samples vere collected on 0.45 xm pore size, mixed cellulose est( r (MCE) filters with backup pads in 25-mm diameter co lducting cassettes with 50-rrnn exten sion cowls. Staplex high volume pumps were used to collect tire samples. The flow rates were 1 I ./min to less than 10 L/min. Flo v rates were checked at the start and end o f each samplii g period using an Asbestos Analytics rotameter, which w is calibrated using a. bubble burette as a primary standard. 11. All workers wer< EPA M odel Accreditation Plan (MAP)<21) accredit 1 and were experienced in asbestos abatement. The san e workers were used at both sites of the urban school dis rict and were employees of the school district. The workt -s conducting the procedures at the third site were fui rished by another licensed asbestos contractor. 12. The Texas Depart! lent of Health is not an OSHA(n) enforcement agency and personal samples were not a part of this study. Pers inal samples were collected by the employer of the wc rkers. Abatem ent Methods Removal o f floor tile at the first site, designated as Room 10 (Figure 1), was conducted under AHERA1(2)345rules. This site, located inside a middle school building of a large urban school district, contained appro|rimately 1000 square feet o f floor tile, which was "flooded" ea :h morning for 3 days preceding the removal. Gross removal was conducted using amended water and hand spud bars* to n lease the tiles from the floor. The 9 X 9 floor tiles had been ii stalled 20 to 25 years before onto a concrete floor and were securely attached. Consequently, re moval of the tiles requ red a great amount of force, which resulted in breakage o f I re tiles into many small pieces. *A spud bar is a steel shaft appro: itcly 2 inches in diameter, with a capered, sharp end to w ork under the floor die. Han< pow er may be used or the bar may be inserted in a pneumatic pow er unit, which cau S the bar to operate in a hammerlike mode. APPL.OCCUP. ENVIRDN.HYG. 11(9) SEPTEMBER. 1996 Fiber Releases in Floor Tile Removal 1 1 1 5 FIGURE 1. Urban middle school, room 10, AHERA removal. FIGURE 3. Commercial building, room 8, dry ice removal. There were three patterns of tile in R oom 10. The pre dominant pattern was light blue-gray in color and occupied approximately 95 percent of the floor area in the room. Anal ysis by PLM o f this tile showed an asbestos content of 4 to 6 percent; ATEM analysis found the amount of asbestos to be considerably higher, 16 to 23 percent. No asbestos was de tected by ATEM analysis of the other two tile patterns. (See Table 1 for analytical results.) The second site consisted o f two rooms o f an administrative building, which had previously been used as an elementary school, of the same urban school district. R oom A (Figure 2) was approximately 1200 square feet and R oom B was approx imately 900 square feet. During this procedure, workers wore full personal protective equipment, which included Type C supplied air respirators. Personal samples were taken by the contractor in accordance with 40 CFR 763, Subpart G, W orker Protection/20^ In R oom A, floor tiles were removed initially using a hand-powered spud bar. Later, due to the difficulty in releasing the tile from the concrete floor, the pneumatic powered spud bar was used. In Room B, floor tile was initially removed dry, using hand-held scrapers in accordance with the RFCI(14) work practices. This method for removal was extremely slow, and sufficient force to remove all pieces of the tile from the floor was not possible. Because the floor tiles were so firmly attached to the concrete floor, the procedures were changed and pneu matic powered spud bars were utilized foi two sampling pe riods. Use of both the hand-held scraper and the pneumatic powered spud bar resulted in many very small sized pieces of detached floor tile. (Analytical results are in Table 2.) The third location was in an unoccupied commercial build ing in East Texas, which contained approximately 1500 square feet. After this area was precleaned, critical barriers were erected, a single inverted polyethylene containment was erected for the walls and the ceding, and differential pressure was established for the area. Work areas were separated and isolated from the air flow from the rest o f the contained area by taped, double-flap doors. The approximate square footage of each work area was 175 to 220 square feet. At this site, methods for the removal o f floor tile included heating, dry ice, FIGURE 2. Urban administrative building, room A, dry pneumatic spud bar removal. FIGURE 4. Commercial building, room 9 RFC1 dry-hand-held scraper. w * u u u u V I <U. TABLE 1. Floor Tile Removal by AHERA R e g io n s Urban Middle School, Room ,0 Bulk Sample Analysis o f Three Patterns o f 9 X 9 Floor T il ID ~ ' De"scription Tan tile Black mastic Light blue-gray tile Black mastic Dark/light green tile PLM None detected None detected 4-6% Chrysotile 1-2% Chrysotile APPL.OCCUP. ENVIRON HYG 11(9) SEPTEMBER 1996 ATEM None detected 16-23% Chrysotile <1% Chrysotile and hand-held scraper R FC I(14) work practices. Removal of mastic was accomplished by amended water/long-handled floor scraper and Abatix 007 mastic remover (Table 3). Following is a description for work in each of the areas where the investigation was conducted at the third location: Room 7: Floor tile was removed by heating the surface with hand-held propane torches to make pliable. Many of the tiles did not readily release from the floor and were broken during J e i r removal flora the floor with hand-held scrapers. (See Table 3A for analytical results.) Mastic was removed after a settling period by R FC I(14) work practices, usmg amended water to wet the mastic and a long-handled floor scraper to peel the ridges down so that the floor would be suitable for installation o f a new tile floor. A HEPA wet vacuum was used to pick up the residue and the floor was mopped to clean it. (See Table 3B for analytical results.) , Room. 8: The floor tile ir ^ lsm om (Figure 3) was removed y dry ice cooling to rele se the dry tiles and/or mastic. A 2-inch thick layer of dry i e was placed in an approximately 2 X 5 foot movable frame with a polyethylene bottom. The dry ice was left at each 1 ication for approximately 3 to 4 minutes. Measurements o f :arbon dioxide (CO ^ levels were made using a Drager pumj and direct indicating C O , tubes about 2 feet above the flooi and above the ftarne. The highest level of C 0 2 measured at th s location was approximately 2500 ppm. The level o f C 0 2 fo nd in the worker breathing zone was approximately 1000 Pi n. The C 0 2 level decreased rap idly as one moved a greater distance above the floor and from the frame. (See Table 3C f r analytical results.) Room 9: The floor tile m Room 9 (Figure 4) was removed usmg the hand-held scraper in accordance with the R FC I(14) recommended work practi es. (See Table 3D for analytical results.) | ' A P P L .O C C U P .E N V IR O N .H Y G . 11(9) SEPTEMBER 1996 Fiber Releases in Floor Tile Removal 1 1 1 7 TABLE 2. Floor Tile Removal by Dry Hand Spud Bar, Dry Pneumatic Spud Bar, and Dry Hand-beld Scraper (RFCI|,IM*Administrative Building in an Urban School District Bulk Sample Analysis o f Three Patterns o f 9 X 9 Floor Tiles ID Description PLM ATEM A Red Tile 10-15% Chrysolite 24--29% Chrysolite Black Mastic 5-7% Chrysolite -- B Gray Tile 10-15% Chrysolite 24--36% Chrysolite Black Mastic 3-5% Chrysolite -- C Brown Tile 7-10% Chrysolite 23-34% Chrysolite Black Mastic 2-4% Chrysolite --. Baseline Air Sample (collected only in Room B due to activity in Room A) VOL PCM ID Description <L) (f/cc) 1-A Rin. B, NW quarter 1479 0.042 ATEM total (st/cc) 0.003 ATEM >0.5 (st/cc) 0.003 ATEM 2=5 (st/cc) <0.003 Room A---Dry Hand Spud Bar ID Description 2-D SW third 2-E S middle 2-F N middle VOL <L) 292 322 284 PCM (f/cc) 0.021 0.040 0.062 ATEM total (st/cc) 0.74 1.2 1.3 ATEM >0.5 (st/cc) 0.63 0.98 1.1 ATEM >5 (st/cc) 0.11 0.20 0.16 Room A --Dry Pneumatic Spud Bar (Day 1) VOL ID Description (L) 2-1 SW third 248 2-J S middle 228 2-K N middle 204 PCM (f/ cc) 0.079 0.12 0.12 ATEM total (st/cc) 6.4 6.0 8.3 ATEM >0.5 (st/cc) 5.7 5.4 7.6 ATEM 2:5 (st/cc) 0.70 0.57 0.73 Bulk Sample Analysis o f Three Patterns o f 9 X 9 Floor Tiles ID Description A Red Tile Black Mastic B Gray Tile Black Mastic C Brown Tile Black Mastic PLM 10-15% Chrysolite 5-7% Chrysolite 10-15% Chrysolite 3-5% Chrysolite 7-10% Chrysolite 2-4% Chrysolite ATEM 24-29% Chrysolite -- 24--36% Chrysolite -- 23-34% Chrysolite -- Baseline Air Sample (collected only in Room B due to activity in Room A) VOL PCM ID Description <L) (f/cc) 1-A Bail. B, NW quarter 1479 0.042 ATEM total (st/cc) 0.003 ATEM >0.5 (st/cc) 0.003 ATEM 2:5 (st/cc) <0.003 (continued) APPL.OCCUP.ENVIRON.HYG. 11(9) SEPTEMBER 1996 ----- " " " Flb`;r Releases in Floor T-i-l-e--R--e--m--o--v-a-l-----1--1--1--9-- K n -' ' l J S f " Hond'Wd * " < - (RFd},"'1D,y ond Removal by Abatix 007 or Amended Water Bulk Sample Analysis o f Two Patterns o f 9 X 9 Floor TilesA ID ~ Description 1A Tan tile Black mastic 2A Tan/Brown mottled tile Black mastic Baseline Air Samples PLM 4-6% Chrysolite ND 7--10% Chrysolite 2--4% Chrysolite ATEM 13--18% Chrysolite 20--27% Chrysolite ID C101 C102 Ul03 Description Room 9 Room 7 Room 2 VOL <L) 918 828 828 PCM (f/cc) 0.029 0.037 0.026 Floor Tile Removal Applying Heat with Hand-held Propane Torch ATEM total (st/cc) 0.030 0.039 0.022 ATEM >0.5 (st/cc) 0.020 0.028 0.017 ID C211 C212 C213 Description Room 7 Room 7 Room 7 VOL (E) 739 850 892 PCM (f/cc) 0.022 0.006 0.011 ATEM total (st/cc) 0.60 0.52 0.25 ATEM >0.5 (st/cc) 0.38 0.34 0.12 Mastic Removal with Amended Water and Extended-handle Floor Scraper (RFCI Work Practices4) ID Description C301 C302 C303 Room 7 Room 7 Room 7 Floor Tile Rem oval U sing D ry IceD VOL <E) 522 540 552 PCM (f/ cc) 0.035 0.027 0.027 ATEM total (st/cc) 0.34 0.26 0.18 ATEM >0.5 (st/cc) 0.13 0.15 0.083 ATEM >5 (st/cc) 0 010 0 Oil 0.005 ATEM (st/cc) 0 VO 0 18 0.13 ATEM >5 (st/cc) 0 2} 0 11 0.099 ID C208 C209 C21.0 Description Room 8 Room 8 Room 8 VOL <L) 666 703 760 Dry Hand-held Scraper (RFCI Work Practices4) PCM (f/ cc) 0.024 0.019 0.024 ATEM total (st/cc) 0.36 0.31 0.19 ATEM >0.5 (st/cc) 0.25 0.23 0.15 ATEM >5 (st/cc) 0.11 0.071 0.036 ID C104 C105 Cl 06 Description Room 9 Room 9 Room 9 VOL (L) 522 509 PCM (f/cc) 0.17 0.15 ATEM total (st/cc) --Pump Stopped-- 1.3 0.96 ATEM >0.5 (st/cc) 0.63 0.51 ATEM >5 (st/cc) 0.67 0.45 (c o n tin u e d ) APPX..OCCUP. ENVIRON. HYG 11(9) SEPTEMBER 1996 Table 3. Continued Mastic Removal Using Abatix 007 Mastic Remover ED C203 C204 C205 Description Room 9 Room 9 Room 9 VOL (L) 1840 1890 1950 Clearance Samples for Commercial Building in East Texas PCM (f/cc) 0.054 0.052 0.048 ATEM total (st/cc) 0.30 0.52 0.32 ATEM > 0 .5 (st/cc) 0.20 0.42 0.22 ATEM S=5 (st/cc) 0.10 0.10 0.10 ATEM VOL PCM total ID Description___________ (L) ( f / cc) (st/cc) C401 C402 C403 C404 C405 Room 7 Room 8 Room 11 Room 1 Room 3 1187 <0.004 1187 <0.004 1345 <0.004 11.00 <0.004 1288 <0.004 <0.005 <0.005 0.004 0,016 <0.004 ATliese types were mixed throughout the building area. 5aTMPles,*,erf taken after the area was cleaned and the containment was erected. The floor was being There was M e breakage. The laboratory report noted altered structures probably caused by the heat 8 ATEM >0.5 (st/cc) <0.005 <0.005 0.004 0.010 <0.004 ATEM 2:5 (st/cc) <0.005 <0.005 <0.004 0.006 <0.004 i/alked on as these samples were taken, wwaius tuusuhaTllvy limited mto z? rtoT4 pUiteecSesmwThehn !bOrCelatrkange- SooccmuerrfelTd. r d e breaka8c occurred from insufficient release, o:*perhaps from brittleness due to the cold. This Following removal o f the floor rile and a settling period, the mastic was removed using Abatix 007 mastic remover. The area was then hand-rubbed with the least abrasive buffer pad to loosen it and the residue picked up using a squeegee. Final cleaning was done by mopping. (See Table 3E for analytical results.) Analytical Procedures b u lk sa m ple a n a ly sis. Bulk sample analyses were conducted using both PLM and ATEM. The PLM procedure was per formed as described in 40 C FR 763, Subpart F, Appendix A.(17) The ATEM analysis was done in accordance with the procedure of Chatfield.(18) For the PLM procedure, random portions of the floor riles were dissected into small fragments while being examined for obvious asbestos fibers. These fragments were dissolved in a small amount o f 1.550 nD dispersion oil by gentle heating, visible fiber bundles were removed and placed in fresh 1.550 nD oil and a large quantity of fresh oil was added to the remaining dispersed sample. The sample was analyzed using magnifications ranging from X7 to X400 Asbestos was iden tified based on morphology (frequently as chopped fragments), color and pleochroism, refractive indices, birefringence, ex tinction characteristics, and sign of elongation. Quantitation was by estimation from models of know-n composition and results were reported as area percent. For the ATEM analysis, 100- to 500-mg samples were shaved from the floor tiles, which were then weighed. These samples were ashed in a muffle furnace at 480 5C. for at least 12 hours and weighed again. The ash was then dispersed in 2 ml o f 6N HC1. W hen effervescence ceased, the residue was collected on a preweighed 0.2-fim polycarbonate filter, where it was rinsed with distilled water, oven dried, and weighed. The residue was resuspended in a known volume of water and 3 ftl of the su plension were transferred to formvar coated grids. After dryii g;,, the proportion of asbestos in the residue was visually estiiii rated at X 16,000 and the upper and lower weight percents 10%) were calculated and reported for asbestos, organic mait n-ial and calcite and dolomite. p h a s e - c o n t r a s t m ic r d sc o py . Phase-contrast microscopy following NIOSH 7400 Revision 3, May 15, 1989 was used to analyze representative po tions of the 0.45-/xm mixed cellulose ester filters for later com) arison with ATEM. Quadrants of the filters were collapsed with acetone vapor, mounted in 1.460 no oil. and coverslippcjjd. The quadrants were analyzed at X400 and fibers greater than 5-p.m long, with aspect ratios equal to or greater than 3, were counted using the NIOSH 7400 A rules. Results w :re reported as fibers per cc. ANALYTICAL TRANSMISSION ELECTRON MICROSCOPY. Elec tron microscopy counts were obtained on the above filters, using the AHERA couiting protocol described in 40 CFR 763, Subpart E, Appendix A or EPA Level II analysis/1s>In brief, upon arrival in the lab, portions of the filters were collapsed on glass slides with acetone vapor and plasma etched until 10 percent of thJ surface was removed. They were carbon coated in a vacuum evaporator and small squares were placed on calibrated 2CH mesh grids. The MCE plastic was removed in an acetone condensation washer. The samples were examined in an A.TEM at a screen magnification of X 16,000 for asbestos fib :rs. Five 200 mesh grid squares were analyzed on each o f twt grids. The AHERA2) protocol was used for the clearance sai spies. To be counted, a structure had to have a 5 to 1 aspect r itio or greater and be at least 0.5 /xm long or greater. Selected area electron difiaction (SAED) and energy dispersive X-ray malysis (EDXRA) were used to con firm all asbestos structure ;. EDXRA alone was used to confirm nonasbestos. The stmetu es were categorized as fibers, bundles, APPL.OCCUP.ENVIRON.HYG. 11(9) SEPTEMBER 1996 Fiber Releases in Floor Tile Removal 1121 TABLE 4. Data Summary Removal Procedures AHERA Dry hand spud bar Dry pneumatic spud bar (Room A) Dry pneumatic spud bar (all cases) RFCI dry hand setaper (all cases) Dry ice Propane torch Abatix 007 mastic remover Wet mastic scraper *ATEM data, incomplete. Mean .030 .041 .11 .092 .096 .022 .013 .051 .030 PCM f/cc Standard Deviation .010 .021 .024 .025 .0073 .0029 .0082 .0031 .0046 Geometric Mean .029 .037 .10 .089 .096 .022 .011 .051 .029 Mean 0.15 1.1 6.9 I* 1.2 0.28 0.46 0.38 0.26 ATEM total st/cc Standard Deviation Geometric Mean 0.078 0.14 0.30 1.0 1.2 6.8 I* . I* 0.23 1.1 0.086 ' 0.27 0.18 0.43 0.12 0.37 0.08 0.25 clusters, or matrices according to AHERA- Results were re corded as asbestos structures greater than or equal to 0.5 j,m to less than 5 pun, or greater than or equal to 5 pun in length per cc and as total asbestos structures per cc. A second ATEM method, known as EPA Level II, was published by Yamate et al.W This method was used to analyze all samples, except the clearance samples. The samples were collected and the filters prepared as in the AHERA(2) protocol. Asbestos structures were counted at X 16,000 and were classi fied as above. SAED and EDXRA were used to identify the structures. The data were made to conform to the AHERA counting rules-2) and were reported using the AHERA guide lines.^2) All samples for electron microscopy were prepared by the direct method, as outlined above. A one-way analysis of variance (ANOVA), associated with a Tukey Studentizcd Range Test, was performed on the ATEM log10 transformed data. The post hoc experiment-wise error rate, representing the probability of at least one falsely declared significant difference, was controlled at 5 percent for the 21 pair-wise comparisons of the seven treatment means. Analytical Results-- Synopsis Representative floor tiles from each site were analyzed by PLM and ATEM. The only asbestos present was chrysotile, and the concentrations ranged from "none detected" to as high as 10 to 15 percent by PLM and 24 to 36 percent by ATEM, both percentages coming from the same tile. The average percent difference between the two analytical procedures was 194 percent, with ATEM always giving the higher results. Only chrysotile was found in the mastics, and it ranged in concentration from "none detected" to 5 to 7 percent by PLM. O f the various removal procedures tested, the propane torch method produced the lowest concentration of airborne fibers per cc, which averaged 0.013 by PCM (see Table 4 and Figure 5). The R FCI[14) hand-held scraper (Room 9) produced the highest average concentration, with 0.16 fibers per cc (See "Analytical Results by Site" and Figure 4). FIGURE 5. ATEM micrograph showing a chrysotile bundle (arrow) visible by PCM. Source was the urban administrative building, room B, dry pneumatic spud bar procedure. Bar = 1 pm. FIGURE 6. ATEM micrograph of chrysotile fiber, seen only by elec tron microscopy. Source was the East Texas commercial building Abatix 007 mastic procedure. Bar = 1 /xm. R.N- Crossman et al. FIBERS PER CC BY PCM APPL.OCCUP. ENVIRON.HYG. 11(9) SEPTEMBER 1996 FIGURE 7. Fibers per cc by PCM. T7.0 1.4 1.2 1 0.8 - 0.6 0.4 0.2 STRUCTURES PER CC BYTEM TEMSTR/CC FIGURE 8. Structures per cc by TEM. APPL.OCCUP.ENVIRON.HYG. 11(9) SEPTEMBER 1996 Kbcr Releases in Floor Tile Removal 1123 PERCENT RESPIRABLE STRUCTURES BY TEM ATEM results indicated the AHERA(2) procedure genetated the least number of asbestos structures per cc, with an average o f 0.15 (see Table 4 and Figure 6). This concentration was significantly lower than that for all other floor tile removal procedures except for the dry ice. The greatest concentrations, averaging 6.9 structures per cc, were produced by the drypneumatic spud bar. These concentrations were significantly higher than those for all other removal procedures. The aver age percent difference between the PCM and ATEM counts for the various floor tile removal procedures was 2840 percent, and the ATEM counts were always the higher. (See Table 4.) The ATEM results also provided insight into the type and size of asbestos structures that were produced by the various removal procedures tested (Figures 7 and 8). The most com mon structures were fibers and matrices, many o f which were respirable. Two amphibole fibers were identified during the electron microscopy analyses of the air samples; however, this was not considered to be a significant finding. The average percentage o f respirable asbestos structures generated by each method is illustrated in Figure 9. The dry-hand-held scraper and the dry-pneumatic spud bar produced the highest percent ages, 96.5 and 90.2, respectively, but all of the removal pro cedures produced at least 48.9 percent or greater respirable structures. The above percentages represent conservatively low esti mates o f the respirable fiactions because the AHERA(2) count ing rules require lengths to be recorded in two categories: those structures greater than or equal to 0.5 /urn to less than 5 /cm and those greater than or equal to 5 /Am. Diameters are not recorded. Therefore, all clusters and matrices greater than or equal to 5 /Am in length were considered nonrespixable, even though some may have been respirable. All fibers and bundles were considered respirable. Discussion The techniques used in this study are those presendy recom mended and/or applied in, floor tile removal. The data from the present studies confirm that asbestos fibers are released in appreciable numbers during application of each of the tech niques. The AHERA procedure resulted in the least genera tion of asbestos-containing dust. Seven of 28 samples taken during dry procedures exceeded 0.1 f/cc by PCM analysis. Two o f these samples were collected during dry removal by R F C I(14) hand-held scraper procedures and were reported as greater than 0.1 f/cc by PCM analysis. Three of four samples collected during dry removal by the RJPCF14> hand-held scraper method were reported greater than 1 str/cc by ATEM. Two of three samples collected during dry removal by hand spud bar were reported greater than 1 str/cc by ATEM. While the purpose o f this study was not focused on evalu ation of potential health effects associated with these activities, it is obvious that a considerable fraction of the asbestos dust is of a respirable size. This point was documented by ATEM analysis of air samples in which the majority of freed fibers were too small to be detectable by the light microscope. Furthermore, any remaining nonrespirable, settled asbestoscontaining particulates can be reduced to a respirable size by foot traffic or maintenance activities and can spread throughout the building. APPL.OCCUP. ENVIRON.HYG H(9) SEPTEMBER 1996 Conclusion Economic considerations have been used to justify decisions for floor tile removal by techniques other than foil contain ment. These decisions frequently do not take into account either the potential exposure to workers and occupants, or the nsk o f contaminating the area o f removal and other adjacent areas. T he expense o f training and compliance with O SH A (1,) and M AP(21) requirements is often a significant consideration. However, while consideration o f these costs is important, the data from the present study suggest that potentially respirable dust is created during floor tile removal and thus exposures occur for the workers and potentially others. Arguments made to the contrary and supported by PCM analysis are shown to be suspect by comparative A TEM analysis. Prudent judgem ent, based on available knowledge, should be used w hen addressing floor tile removal procedures. The following recommendations are made to aid industrial hygien ists and asbestos project designers: 1. Analyze all floor tile by A TEM bulk methods when re potted 1 percent or less by PLM. Assuming asbestos at greater than 1 percent is always an option. 2. Conduct floor tile removals using a negative pressure en closure, with polyethylene (1 layer) on walls and ceiling. 3. Use w et methods for floor tile removal. 4. Following cleanup and visual inspection, apply lock-down and allow to dry and settle. 5. Collect clearance samples by aggressive methods in accor dance w ith 40 C F R 763, Subpart E .(2> 6. Analyze clearance samples by A TEM in accordance w ith 40 C FR 763, Subpart E. References 1. U.S. Environmental Protection Agency: 40 CFR 61, Subpart M, Section 763.90 and 763.91. Fed. Reg. 55:48414-48433 (No vember 20, 1990). 2. U.S. Environmental Protection Agency: 40 CFR 763, Subpart E. Fed. Reg. 52:41848-41850 (October 30, 1987). 3. U.S. Environmental Protection Agency: Advisory Regarding Availability of an Improved Asbestos Bulk Sample Analysis Test Method; Supplementary Information on Bulk Sample Collection and Analysis. Fed. Reg. 59:38970-38971 (August 1, 1994). 4. National Voluntary Laboratory Accreditation Program: National Institutes of Science and *1echnology, Gaithersburg, Maryland (1991), 1 5. U.S. Environmental Protection Agency: Method for the Deter- mination ofAsbestos in lulk Building Materials. 600/R-93/116, July (1993). Hammar, S.P.; Dodson R.F.: Asbestos. In; Pulmonary Pathol- ogy, pp. 901-983. D.. I. Dail, S.P. Hammar, Eds. SpringerVerlag, New York (19( 4). 7. Dodson, R.F.; Williams M.G.; Com, C.J.; et al.: A Comparison of Asbestos Burden in Lung Parenchyma, Lymph Nodes, and 8. Plaques. Ann. N.Y. Ac; d. Sebastien, P.; Bignon, J ' Sci. ' 643:53-60 (1991) Martin, M.: Indoor Airborne Asbestos Pollution: From the C< ling and the Floor. Science 216T410- 1412 (1982). ' - Schultz, B.; et al.: Airborne Asbestos in Public Buildings. Enviri at. Res. 51:100-107 (1990). 10. U.S. Environmental Pro :ection Agency: Airborne Asbestos Con c11e5Cn9Qtr(/a11tO9io9Qn3qs)\.During B ui tig of Resilient Floor Tile. 600/SR-9"3/ 11, U.S. De-partment o flib o r: 29 CFR 1926.1101, Fed. Reg 59:41142 (August 10, 1 >94). 12. U.S. Environmental Pr< tection Agency: Policy Clarification for Asbestos Hazard Emei pmey Response Act (AHERA) lulv (1992). J y 13. U.S. Environmental Pr< tection Agency: Asbestos, Manufacture, Importation, Processing and Distnbution Prohibitions. 40 CFR 763, Fed. Reg. 58:5896 7 (November 5, 1993). 14. Resilient Floor Coverir g Institute: Recommended Work Prac tices for the Removal cf Resilient Floor Coverings. Rockville Maryland (1990). ' 15 Texas Civil Statutes: An cle 4477-3A, 12, Senate Bill 1341 and House Bill 79, 72nd I egislaturc, 1991, House Bill 1680 and House Bill 1826, 73rd 1 cgislature (1993). 16. Yamate, G.; Agarwal, S. 5.; Gibbons, R.D.: Methodology for the Measurement of Airbo ne Asbestos by Electron Microscopy. Washington, D.C.: Offi ;e of Research and Development, U.S. Environmental Protectii n Agency. Contr. (1984). ' 17. U.S. Environmental Prc :ection Agency: Interim Method for the Determination of Ashes os in Bulk Samples. 40 CFR 763, Fed. Reg. 52, Appendix A e Subpart F (October 30, 1987). 18. U.S. Environmental Prt tection Agency. Chatfid'd, Eric J. SOP: ATEM Bulk Sample At alysis of Floor Tile. 1988-02, Rev. 1. 19. U.S. Department of Lai or: Asbestos Standard for Construction Industry. 29 CFR 1921.58, Fed. Reg. 51:22-612 (Tune 20 1986). ' 20. U.S. Environmental Pi jtection Agency: Asbestos, Abatement Projects; Worker Protec ion. 40 CFR 763, Subpart G, Fed. Reg. 52:5623 (February 25, 1987). 21 U.S. Environmental Projection Agency: Asbestos Model Accred itation Plan. 40 CFR 7n|3, Appendix C to Subpart E, Fed. Ret?. 59:5236 (February 3, 1TJ94). r