Document 8RXkLJxEY6jBEmZbG16rjw4Z

United States * Environmental Protection Agency _________ Research and Development V E ^Water Erwineering ResearchfLaboratoiyCincinnati OH 4^265 t1 DAR . \ EPA/600/S2-86/07Q^Jan. 1_E8?-^oe ' * Project Summary ^7=---'''*'* * E. A. ROMAGNOLI Assessment of AsjayMethods for Evaluating Asbesto^ Abatement Technology at the Corvallis Environmental Research Laboratory Mark A. Karaffa, Robert S. Amick, Ann Crone, and Charle: Two analytical methods and two sampling techniques were evaluated for their effectiveness in a project to re move air-entrainable asbestos from the Corvallis Environmental Research Lab oratory in Corvallis, Oregon. The two analytical methods were phase con trast microscopy (PCM) and transmis sion electron microscopy (TEM). The sampling techniques included a static (nonaggrassive) method and an aggres sive one using a blower. Air sampling was conducted at an EPA office building that had undergone an amosite asbestos abatement pro gram. The aggressive sampling tech nique revealed that air-entrainable as bestos remained in work areas after completion of abatement actions. Re sults also confirm that under similar sampling conditions, TEM analysis de tects more fibers than PCM because of the former's better resolving capability. Because PCM does not discriminate be tween asbestos and other fibers and cannot resolve fibers thinner than about 0.2 pm, this method may not ac curately reflect the true hazard poten tial. f TEM coupled with aggressive sam pling should be recommended as the analytical method of choice for final post-abatement clearance testing. -J This Project Summary was devel oped by EPA's Water Engineering Re search Laboratory, Cincinnati, OH, to announce key findings of the research project that is fully documented In a separate report of the same title (see Project Report ordering information at back). Introduction Background The Technical Assistance Program of the Office of Pesticides and Toxic Sub stances of the U.S. Environmental Pro tection Agency (EPA) provides guidance and information on the identification of asbestos-containing materials in build ings and on the correction of potential asbestos hazards. Four EPA Guidance Documents contain much of the exist ing technical information about as bestos in nonindustrial settings.1*4 These documents describe how to es tablish an asbestos identification and control program, provide background information and direction to school offi cials and building owners on exposure assessment, and give instruction on how to develop and implement an as bestos abatement program. The most recent asbestos guidance from EPA not only emphasizes recent experience and new information on asbestos control but also introduces and discusses crite ria for developing an appropriate as bestos control plan. Considerable scientific uncertainty still surrounds the effectiveness of specific abatement actions in reducing the risk of exposure to airborne as bestos. One critical concern among those responsible for asbestos abate- ASARCO ALV 0002652 ment is how clean the contractor leaves a'building (or building area) after re moving the asbestos material or after completing work that could have dis turbed an asbestos-containing material (e.g., encapsulation, enclosure, or spe cial maintenance operations). The two criteria recommended by the EPA guid ance (1983)3 that was in effect at the out set of this study were visual inspection of the worksite and air monitoring after completion of the project. Visual inspec tion should detect incomplete removal, damage caused by abatement activity, and (most important) the presence of debris or dust left by inadequate cleanup of the work area. Air monitor ing by the membrane filter collection technique and phase-contrast micro scopic (PCM) analysis are recom mended to supplement the visual in spection and to determine whether elevated levels of airborne fibers gener ated during the removal process have been sufficiently reduced. This currently recommended optical microscopic technique is one of two methods speci fied by the National Institute for Occu pational Safety and Health (NIOSH) to determine airborne fiber concentra tions; it is used by the Occupational Safety and Health Administration (OSHA) to measure total airborne fibers in occupational environments. The EPA-recommended airmonitoring methodology for determin ing abatement completion (NIOSH Method No. P&CAM 239) was as fol lows: Air sampling should begin after the project has been completed and all surfaces in the abatement site have been cleaned, preferably within 48 hours after abatement work is finished. A minimum of three air monitors per worksite and at least one per room is rec ommended. Air is drawn through a membrane filter for about 8 hours at a flow rate of approxi mately 2 L/min. A total air volume of approximately 1,000 liters col lected at the specified flow rate should be sampled. After the sam pling, a section of the filter is mounted on a microscope slide and treated to form a transparent, optically homogeneous gel. The fibers are sized and counted by using a phase-contrast micro scope at 400 to 450X magnifica tion. For counting purposes, a fiber is defined as a particle with a physical dimension longer than 5 2 micrometers and a length-todiameter ratio of 3 to 1 or greater.3 This method is intended to give an in dex of the airborne concentration of fibers of specified dimensions in an at mosphere known or suspected to con tain asbestos; it is not designed to count fibers less than 5 p.m long or to differen tiate asbestos fibers from other fibrous particulates. The most significant limitation of the PCM method compared with transmis sion electron microscopy (TEM) and scanning electron microscopy (SEM) is that PCM is limited in the detection of fine particles (i.e., those with submicron diameters or lengths less than 5 p.m) that may be toxicologically significant. For example, in glove-box tests of simu lated industrial mechanical operations on asbestos-containing products (drilling, sawing, and sanding), the PCM method counted fewer than 1 percent of the fibers counted by TEM.8 Although conditions of this glove box study were obviously different from asbestos abatement activities, some concern ex isted about the relative merits and capa bilities of the different analytical meth ods used to determine representative fiber concentrations. Another study es timated that small asbestos fibers (i.e., fibers less than 0.2-p.m wide and 5-p.m long that are not detected by the PCM method) were present at 50 to 100 times the concentration of the larger, optically visible fibers.* Study Objective The objective of this research project was to identify and quantify the air borne amosite asbestos fibers present in building atmospheres after an as bestos remedial activity was completed and the building was reoccupied. The project focused on the adequacy of EPA's previously recommended PCM method of analysis and static sample collection technique. The PCM method was compared with TEM methods, and the feasibility of an alternative aggres sive sampling technique was investi gated. The results of this study estab lished the advantages and limitations of applying PCM and TEM analytical meth ods, both separately and in conjunction with an aggressive sampling technique, to the evaluation of air quality following asbestos abatement Reliable methods of air sampling and analysis permit the use of monitoring results to be included in evaluating the efficacy of asbestos abatement meth ods and in developing better technical guidance for abatement contractors, building owners, and other parties di rectly responsible for remedial asbestos programs. Active or recently completed abatement sites were selected for moni toring because they provided an excel lent opportunity to collect real-world data, and because the monitoring tasks could be arranged with minimum lead time and coordination. The conditions in a work area while the final air samples are collected can greatly influence the results of a posta batement assessment After an abate ment action, the air is usually sampled under static conditions--that is while the area is sealed off, before ventilation is restored, and after at least a 24-hour settling period following the final wet cleaning. Consequently, this monitoring technique may fail to detect residual fibers that have settled on horizontal surfaces or that were missed by the cleaning. Residual asbestos fibers constitute a potential exposure hazard because they could be reentrained later, when the air in the area is agitated by personnel traf fic, air flow from ventilation systems, and custodial activities. Thus, for more accurate characterization of postabate ment fiber concentrations, the work area should experience appreciable air movement to simulate actual use condi tions during air monitoring. The introduction of air turbulence into the work area during the collection of stationary air samples is termed `aggressive sampling.' This method entails the creation of air movement by the use of blowers, fans, brooms, or compressed air streams to entrain any particulate matter that may be present. The advantages of the aggressive sam pling technique over the static (or nonaggressive) sampling are that the former reflects worst-case conditions and that the testing requires a relatively short period. The disadvantages are that this technique is not readily stand ardized or reproducible, nor does it re flect normal exposure levels to occu pants. As with the static sampling method, no criteria have been estab lished to define an acceptable or safe level of fibers in a nonoccupational en vironment. The research on fiber con centration levels using the PCM and TEM methods is continuing so that the before-, during-, and after-abatement criteria can be developed within the next 2 years. ASARCO ALV 0002653 *roject Description Site Selection Air monitoring was conducted at two selected sites from which friable as bestos building materials had been re moved: Site 1, Columbus East High School. Columbus, Indiana; and Site 2, the EPA Environmental Research Labo ratory in Corvallis, Oregon. This report describes only the results of the air monitoring survey conducted at Site 2. The monitoring data from Site 1 and the significance of these data are the subject of a separate report (Assess ment of Assay Methods for Evaluating Asbestos Abatement Technology: Columbus East High School, Columbus, Indiana. EPA/600/2-86/053). These se lected sites met the following criteria: The abatement plan involved the re moval of friable, spray-applied, asbestos-containing material. The contractors carried out the work area preparation, removal, and de contamination in accordance with EPA-recommended specifications and requirements.1 Multiple work areas containing ho mogeneous asbestos material were available for monitoring. The building owner and abatement contractor agreed to cooperate with EPA and to provide access to se lected areas of the building. Building Description The Corvallis Environmental Re search Laboratory (CERL) is housed in a two-story, reinforced-concrete structure built in 1966. The building contains a total gross area of approximately 465 m2 (45,000 ft2). A single-pass heating, ventilating, and air conditioning (HVAC) system supplies the occupied building areas with 100 percent outside air. The outside air enters through intakes on the roof, is tempered by hearing or chill ing coils, and is distributed by a closedduct system to ceiling-mounted dif-'~ fusers in all rooms and laboratories. Air flows through louvers in the bottom of interior doors and passes into the hall ways (which serve as air plenums to the outside), or it is exhausted through lab oratory fume hoods. Asbestos-containing Materials Asbestos-containing insulation had been spray-applied and tamped on to the concrete ceiling (beams and deck) of four rooms (Rooms 146, 155, 157, and 59) and the penthouse in the main JERL facility and on beams in the boiler room (Room 163). The large air intakes located under the building, which sup ply ventilating air to the boiler and chiller room, were also lined with as bestos. The insulation material on the ceilings of Rooms 155,157, and 159 and in the air ducts had been removed in 1984 during a controlled abatement program. The asbestos-containing insu lation in Room 146 (deionizer room), the boiler room, and the penthouse was still in place. Samples collected from Room 146 and the penthouse were analyzed by polarized light microscopy and disper sion staining. The results indicated 80 percent amosite asbestos in each of the two bulk samples analyzed. At the time of the survey, the remaining insulation material was characterized as highly fri able, loosely packed, and showing some signs of deterioration (loose, hanging pieces were visible). Methods and Procedures The sampling procedures and analyti cal methods are outlined briefly here. They are described fully in the full re port and in the project summary for Site 1 (Assessment of Assay Methods for Evaluating Asbestos Abatement Tech nology: Columbus East High School, Columbus, Indiana, EPA/600/2-86/053). Abatement Program The asbestos-containing insulation in Rooms 155,157, and 159 and in the air intakes was removed between May 21 and July 2, 1984. The abatement plan and schedule prepared by the contrac tor and submitted to CERL were re viewed and approved by EPA before work was begun. The work plan was in accordance with the then-current EPA guidelines and EPA and OSHA asbestos regulations for asbestos removal and decontamination. On completion of the abatement effort CERL personnel sur veyed the work performed by the abate ment contractor, performed additional cleaning of the work areas, and made arrangements for the painting of all ceil ing surfaces from which the asbestos insulation had been removed. According to CERL accounts, each work area was isolated from the rest of the building by temporary barriers. Ven tilation ducts and openings to the out side or to adjacent rooms were sealed. Walls and floors were covered with plastic sheeting. Fully protected abate ment workers first wetted the insulation with amended water and then scraped it off. The asbestos-containing debris was placed in sealable plastic bags and dis posed of at a local EPA-approved sani tary landfill. Each work area was cleaned three times, and a settling pe riod of 24 hours was allowed between cleanings. The ceiling surfaces were painted to bond any residual fibers not removed by the scraping, brushing, and wet-cleaning. Monitoring Approach The sampling strategy for this study was to collect representative samples for PCM and TEM analysis from (1) rooms where friable asbestoscontaining insulation had been re moved, (2) rooms that were never treated with asbestos-containing mate rials, and (3) outdoors. Samples for sub sequent PCM and TEM analyses were collected from two or three representa tive locations in each room approxi mately 6 weeks after completion of all abatement activities. Two of the three monitored rooms from which asbestos insulation had been removed had been reoccupied. (Room 159 was vacant at the time of the survey.) Both static and aggressive sampling techniques were used in each room. The static sampling was conducted first during regular working hours while the facility was oc cupied. The aggressive sampling was conducted on a Saturday when the sam pling areas were unoccupied. Filter holders containing either 0.8-|i.m Millipore* mixed-cellulose ester (PCM) or 0.4-|i.m Nuclepore polycarbonate filters (TEM) were positioned 1.3 to 1.5 m (4 to 5 ft) above the floor at arbitrary loca tions. Battery-powered sampling pumps were used to draw air through the filters. The constant-flow pumps were calibrated to 2.5 L/min and were operated for 8 hour per test Samples were collected concurrently at outdoor locations during each monitoring pe riod. On completion of each monitoring survey, samples were submitted to the appropriate laboratory for preparation and analysis. The Nuclepore filters were carbon-coated before they were trans ported to the laboratory for TEM analy sis. Overview of Air Sampling Strategy Samples designated for PCM and TEM analysis were collected with both `Mention of trtde names or commercial products does not constitute endorsement or recommends' tion for use. 3 ASARCO ALV 0002654 static and aggressive methods in six dif ferent rooms. Samples were also col lected in the surrounding environment outside the building. The areas sampled included three rooms that had been treated previously with asbestos insula tion and have since been abated and rooms that have never been treated with asbestos. Representative samples for PCM and TEM analysis were col lected approximately 6 weeks after all abatement activities had been com pleted. Outdoor air samples were col lected concurrently with indoor sam ples on the roof of the building or at ground level in the open field west of the main building. Side-by-side samples (one for PCM, one for TEM) were collected in each room under static and aggressive sam pling conditions. The number of sam ples per room was not specified by the study design, but three of each type of sample were collected within each room. The static sampling was per formed first during regular working hours with the building occupied and the HVAC system operating. The ag gressive sampling was performed on a Saturday while the sampling areas were unoccupied and the HVAC system was not operating. Placement of the sam pling equipment within each work area was the same during both static and ag gressive sampling. > Results Air Monitoring Results Table 1 presents a detailed listing of the results of PCM and TEM analysis of samples collected under aggressive and static sampling conditions after abate ment. With one exception, all concen trations of asbestos fibers and total structures under aggressive sampling conditions were higher than the corre sponding measurements made under static sampling conditions. The excep tion involved two samples with differ ences that were considered negligible because they were below the limit of reliable quantitation for the analytical method. Comparisons of PCM and TEM analy ses of samples collected under, static and aggressive sampling conditions are presented graphically in Rgure 1, which is based on the data results presented in Table 1. 4 Statistical Comparisons Statistical Method of Analysis The Mann-Whitney test was used to determine whether the observed differ ences in analytical methods and sam pling conditions were statistically sig nificant7 Use of the Mann-Whitney test required no prior assumption regarding the nature of the underlying probability distribution function of measurements of asbestos fiber concentrations. Analytical Methods Tables 2 and 3 compare the geometric averages of fiber concentrations deter mined by PCM and TEM analyses under static and aggressive sampling condi tions. Table 4 summarizes these results. Based on the application of the MannWhitney test and the assumption that the fiber/volume concentrations are comparable, the difference between PCM and TEM results is statistically sig nificant (i.e., p < 0.03) for samples col lected outdoors and indoors in abated areas under static conditions. The dif ference between PCM and TEM results from indoor sampling of nonasbestos areas was also statistically significant (p < 0.10) under static sampling condi tions; however, this conclusion was based on a small sample size (n = 3). The ratios of TEM/PCM concentrations for static sampling were 3.0 for ambient samples, 3.3 for indoor abated-area samples, and 7.5 for indoor nonasbestos-area samples. The difference be tween PCM and TEM results is not statistically significant (i.e., p> 0.005) for indoor samples from both abated and nonasbestos areas under aggres sive sampling conditions. For aggres sive sampling in abated areas, the ratio of TEM/PCM was 1.8. For aggressive sampling in nonasbestos areas, the ratio of TEM/PCM was 1.9. Sampling Conditions Table 2 also compares static and ag gressive sampling conditions for PCM and TEM analyses in both abated and nonasbestos areas. The difference be tween the geometric average fiber con centrations under static and aggressive sampling conditions was statistically significant (i.e., p < 0.002) for both PCM and TEM in abated areas. For PCM analyses, the ratio of aggressive to static fiber concentrations was 7.0; for TEM analyses, the ratio was 3.7. For sampling conducted in nonasbestos areas, the difference between the geo metric average fiber concentrations under static and aggressive sampling conditions was statistically significant for PCM analyses (i.e., p < 0.002) but not statistically significant for TEM analyses (i.e., p>0.04). For nonas bestos areas, the ratio of aggressive to static fiber concentrations for PCM analyses was 8.0; for TEM analyses, the ratio was 2.0. Comparison of Indoor Abated Samples and Ambient Samples Also included in Tables 2,3, and 4 are the PCM and TEM analyses of samples collected in the ambient atmosphere and in indoor abated areas. The difference between asbestos con centrations measured under aggressive sampling conditions in indoor abated areas and those measured in ambient samples was statistically significant (p < 0.02). The ratio of asbestos concen trations measured by TEM under ag gressive sampling conditions in indoor abated areas to ambient TEM concen trations was 6.2. Comparison of Indoor Nonas bestos Samples and Ambient Samples For samples analyzed by PCM, the ge ometric mean asbestos concentration for indoor samples collected statically in nonasbestos areas was below the de tection limit of the analytical method, as were the ambient PCM samples. Conse quently, no meaningful comparisons can be made. For PCM samples col lected aggressively, the geometric mean concentration was 0.016 x 10* fibers/m3 compared with lower than 0.002 x 106 fibers/m1 for ambient sam ples, a ratio of 16.0 (if a concentration of 0.001 x 10 fibers/m3 for ambient sam ples is assumed). This observed differ ence was statistically significant (p>0.01). One nonasbestos area (Room 152, the instrumentation labora tory) was extremely dusty, so the ag gressive sampling procedure entrained large quantities of house dust that had accumulated on shelf and cabinet tops over many years. This fact accounted for the relatively high PCM fiber counts. For TEM samples collected inside nonasbestos areas under static condi tions, the geometric mean asbestos fiber concentration was 0.015 x 10 fibers/m3 compared with 0.006 x 10 fibers/m3 for TEM ambient samples, a ratio of 2.5. This observed difference ASARCO ALV 0002655 .001 I Nonasbestos Areas Aggressive TEM mu Nonasbestos Areas Aggressive PCM MBilium Nonasbestos Areas Nonaggressive TEM Nonasbestos Areas Nonaggressive PCM Abated Areas Aggressive TEM HHHHnii Abated Areas Aggressive PCM m n AbatedAreas Nonaggressive TEM Ambient ' PCM iiiiiiii Abated Areas Nonaggressive PCM Ambient TEM .002 .003 .004 .005 .007 .010 .020 .030 .040 .050 .070 .100 25% 75% Percentiles l .200 .300 .400 .500 .700 1.00 10* Fibers/m1 Figure 1. Comparison of airborne fiber concentrations for PCM and TEM under static (nonaggressive) and aggressive conditions. 2.00 was not statistically significant (i.e., p>0.10), nor was it significant under aggressive sampling conditions (i.e., p>0.10), where the ratio was 5.0. Be cause the comparisons of fiber concen trations for TEM samples in nonas bestos areas and ambient samples are based on very small sample sizes (n3 and n = 2, respectively), the pbserved differences are not statistically signifi cant at a probability level of >0.05. Comparison of Samples From Indoor Abated and Nonasbestos Areas For all PCM samples (aggressive and static), the observed differences in fiber concentrations^ indoor abated and nonasbestos areas were not statistically significant (p > 0.08 for static conditions and p > 0.05 for aggressive conditions). For PCM samples collected under static inditions, the ratio of fiber concentrajns in abated areas to nonasbestos areas was 3.0 (a concentration of 0.001 x 10 fibers/m3). For PCM sam ples collected under aggressive condi tions, the ratio was 1.3. For all samples analyzed by TEM, the difference between abated and nonas bestos areas was also.not statistically significant (p>0.10 for static condi tions). For TEM samples collected under static conditions, the ratio of asbestos fiber concentrations in abated to nonas bestos areas was 0.7. Under aggressive conditions, this ratio was 1.3 for as bestos structures, and 1.2 for asbestos fiber concentrations. Conclusions The following conclusions resulted from this study: 1. The aggressive sampling tech nique used in this problemdefinition study revealed that airentrainable asbestos fibers were present in previously abated areas. TEM analysis of aggressive sam ples from building areas that were never treated with asbestos insula tion also revealed detectable levels of asbestos fibers. 2. Regardless of the analytical method used, the fiber concentra tions measured under aggressive sampling conditions were signifi cantly higher than those measured under static conditions. The ratios of aggressive to static PCM fiber concentrations in abated and nonasbestos areas were 7.0 and 8.0, respectively. By TEM analysis, these ratios were 3.7 and 2.0. 3. The study results clearly demon strate that under similar sampling conditions, TEM analysis identifies more fibers than PCM. The ratio of TEM/PCM fiber concentrations for static sampling was 3.0 for ambi ent samples, 7.5 for indoor nonas bestos areas, and 3.3 for indoor abated samples. The ratios for ag gressive sampling in indoor areas were about 2 to 1. 4. Asbestos concentrations deter mined by TEM in abated areas with ASARCO ALV 0002656 Table 1. ResubIs of PCM and 7EM Analysis Nonaggressiva PCM TEM PCM Sample Sample 10* Asbestos9 10* Asbestos > Sample Sampling Location Number 10* Fibers/m3 Number Fibers/m* Strudures/m* Number 10* Fibers/m* Aggressive TEM Sample 10* Asbestos* 10* Asbestos' Number Fibers/m3 Structures/m* Abated areas Room 155 ` Room 157 Room 159 COR-02 COT-03 COT-07 COT-04 COT-OS COT-OS COT-OS COT-07 COR-09 0.007* 0.002* <0.002* 0.008* 0.006* 0.01* <0.002* <0.002* 0.004* C0R-NO2 COR-N-03 COR-N41 C0R-NO4 COR-N-OS COR-N46 COR-N08 COT-N-07 COfl-N-09 0.006 0.016 0.010 0.018 0.017 0.012 <0.005* 0.006 0.011 0.006 0.016 0.010 0028 0017 0012 <0.005 0.006 0.011 COT-27 COR-25 COR-26 COR-28 COT-29 COT-30 COT-37 COT-46 COT-34 0002* 0.01* 0.007* 0.032 0.048 0035 0.045 0.045 0.057 COR-N-27 COR-N-25 COR-N-26 COR-N-28 COR-N-29 COR-N-30 COR-N-31 COR-N-46 COR-N-34 0.017 0.041 0.024 0.041 0104 0059 0.060 0.025 0.022 0.022 0.041 0.024 0.041 0.104 0.065 0.066 0.025 0.028 Nonasbestos areas Room 173 COR-13 COT->4 Room 152 COR-10 COR-1B Room 205 COT-75 COT-71 COR-17 <0.002* 0.002 <0.002* 0.002 <0.002* <0.002* 0.005' COR-N-13 COR-N-14 COR-N-10 COR-N-15 COR-N-19 COR-N-11 CORN-17 0011 0012 * ft 024 0.011 0012 0024 COR-3S COR-36 COR-37 COR-36 COT-40 COR-39 COR-41 0.044* 0.003* 0.17 0.18 0.07* 0.008* 0.01* COR-N-35 COR-N-36 COR-N-37 COR-N-38 COR-N-40 COR-N-39 COR-N-41 0.006 01735 0.032 0.005 0.14$ 0.032 Outdoors (ambient1 Ground COT-27 COT-44 <0.002* <0.002* COR-N-21 COR-N-44 <0.0061 <0.006* Roof COT-43 COT-78 COT-42 <0.002* <0.002* <0.002* CQR-N-43 COT-TV-IS COR-N-33 0011 0.011 ## Blanks COT-45 COT-47 COT-48 COT-49 OnOO'< onooft onoo" ortoo" COR-N-60 COR-N-61 020" 1/20** 0/20" 1/20** -Fiber concentration band on tha total number of asbestos fibers counted. rConcentration based upon the total number of chrysolite and amphibole structures counted. These asbestos structures include asbestos fibers, asbestos matrices/debris, asbestos dusters/dumps. and asbestos bundles. 'Less than 10 fibers in 100 fields ware counted. Fiber concentration based on tha adual number of fibers counted in 100 fields. Fiber concentration is below the reliable limit of quantitation lie. 10 fibers in 100 fields).7 *No fibers were deteded In 100 fields. Below the detection limit (e.g., counting ft5 fiber in 100 fieldsl. IBelow detection limit (no fibers or structures counted in 20 grid openings!. --Sample collected but nor analysed. HNo fibers were deteded in 100 fields. "No asbestos fibers or structures were deteded in 20 grid openings. aOne asbestos fiber or structure was detected in 20 grid openings. Table Z Comparison of Static and Aggressive Sampling Results for Postabatement Testing Neneggretaive _________ Aggressive Semples Included m Comparison KM No. at F&OfSe* No. of Semples 10*/m* Semples 7TM Asbestos fibers.* 10*/m3 * Asbestos Serve* turns.' 10*/m3 7EM/PCM Fibers KM No. of Fibers,* Semple% 10*/m3 No. of Semples TtU Asbestos Fibers. * 10*/m3 Asbestos Strve* tores.* 10*/m* TEM/PCM Fibers PCM TEM Aggres Aggresshre/Ststk sive Fibers.' Asbestos Asbestos 10*/m3 Fibers Structure Abated ernes 9 0MB 9 0.010 0410 13 9 0.021 9 0.037 0.040 14 74 17 44 Honssbostos sreaa 7 <0.002 3 0JJ1S 0.018 74 7 0416 3 0.030 0431 14 94 2.0 21 Outdoors m S <0.002 2 0.006 0.006 10 0- a - - - -- - `Att concentrations are geometric meena. 6 ASARCO ALV 0002657 aggressive sampling were signifi cantly (6.2) times higher than am bient TEM concentrations. The TEM concentrations under aggres sive conditions in the nonasbestos areas were 5 times higher than am bient TEM concentrations, but this difference was not statistically sig nificant Recommendations Although time-consuming and ex pensive, TEM should be recommended as the analytical method of choice for measuring airborne asbestos fiber con centrations for final clearance testing of work areas after asbestos abatement. After a standardized TEM protocol and an aggressive sampling procedure are incorporated into asbestos guidelines, a criterion should be established to define an acceptable asbestos fiber concentra tion in building areas after asbestos abatement. Continued research should focus on the development of a quicker, less expensive method for monitoring buildings after asbestos abatement and on more efficient abatement practices. References 1. U.S. Environmental Protection Agency. Asbestos-Containing Mate rials in School Buildings: A Guidance Document, Part 1. Office of Toxic Substances, Washington, D.C. 20460. March 1979. 2. Sawyer, R.N., and D.M. Spooner. Asbestos-Containing Materials in School Buildings: A Guidance Docu ment, Part 2. Office of Toxic Sub stances, U.S. Environmental Protec tion Agency, Washington, D.C. 20460. March 1979. 3. U.S. Environmental Protection Agency. Guidance for Controlling Friable Asbestos-Containing Materi als in Buildings. EPA/560/5-83-002, Office of Toxic Substances, Wash ington, D.C. 20460. March 1983. 4. U.S. Environmental Protection Agency. Guidance for Controlling Asbestos-Containing Materials in Buildings. EPA/560/5-85-024, Office of Toxic Substances, Washington, D.C. 20460. June 1985. 5. Falgout, D. Environmental Release of Asbestos From Commercial Product Shaping. EPA/600/2-85/044, Engineering-Science, Fairfax, Vir ginia. August 1985. 6. Chatfield, E.J. Measurement of As bestos Fibre Concentrations in Ambi ent Atmospheres. Study No. 10, On tario Research Foundation. 1983. 7. Mosteller, F., and R.E.K. Rourke. Sturdy Statistics: Nonparametrics and Order Statistics, Addison Wesley, Reading, Massachusetts. 1973. The full report was submitted in fulfill ment of Contract No. 68-03-3197 by PEI Associates, Inc., under the sponsorship of the U.S. Environmental Protection Agency. fable 3. Comparison of Sampling Results by Sample Location* Sample Location Comparisons Samples Included in Comparison PCM-Static PCM-Aggressive TEM-Static TEM-Aggressive Indoor Abated/ Indoor Nonasbestos 3.0 1.3 0.710.7)' 13(1.3)' Indoor Abated/ Outdoors 3.0 3.5 1.7 (1.7)' 6.2 (6.7)' Indoor Nonasbestos/ Outdoors 1.0 16.0 2.5(2.51' 5.0 (5.2)' `All quantities are ratios of the geometric mean fiber concentrations. For PCM samples, fiber concentrations include all fibers greater than 5 pm in length; for TEM samples, fiber concen trations include all asbestos fibers. 'Ratio of geometric mean concentrations of asbestos structures. Table 4. Summary Comparison of PCM and TEM Analyses of Air Samples Collected During Static and Agressive Conditions' Nonasbestos Areas Abated Areas Analytical Technique Outdoor (Ambient) Static Aggressive Static Aggressive PCM, fibers (>S yunf/m3 BDL' BDL BLRQ' BLRQ BLRQ (16,000) (3.000) (21.000) TEM, asbestos fibers/m3 6.0001 15,000 30,000 10,000 37,000 TEM, asbestos structures/m* 6,000 15.000 31,000 10,000 40.000 `All values are geometric means. 'BDL " Below detection limit {1,136 fibers/m3). 'BLRQ " Below limit of reliable quantitation (*22,720 fibers/m3). Geometric mean based on fwo sample values. One sample value was below the detection limit for TEM analysis (*5,688 asbestos fibers or structures/m3). 7 ASARCO ALV 0002658 % Mark A. Karatfa. Robert S. Amick. Ann Crone, end Charles Zimmer ere with V. PCI Associates, Inc.. Cincinnati. OH 45246-0100. William C. Cain is the CPA Project Officer (see below). The complete report, entitled "Assessment of Assay Methods for Cveluating Asbestos Abatement Technology at the Corvellis environmental Research Laboratory."(Order No. PB 87-110961/AS; Cost: $13.95. subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield. VA 22161 Telephone: 703-487-4650 The CPA Project Officer can be contacted at: Water engineering Research Laboratory U.S. environmental Protection Agency Cincinnati. OH 45268 U S. Or riu.nL ftif-w;. /^ HAS:3'3/ \ oeiiTY U.S.POSIAGE i- , os /;*;= 0 . 2 - U 31531531 United States Environmental Protection Agency Official Business Penalty for Private Use 3300 EPA/600/S2-86/070 Center lor Environmental Research Information Cincinnati OH 45268 0041106 WERL EMIL ROMAGNOLI ~a~SflRC0 INI1 180 MAIDEN LANE _NEM Yoar ___________ ^ 13038 ASARCO ALV 0002659