Document 9J37j3N41Gxgo0Vw1pGD2kzL5

\PKJI. IWOt V TECHNICAL PLAINTIFF'S EXHIBIT ECO.N "Living with TEM Clearance" By Richard J. Lee and Ian M. Stewart Introduction In October of 1986. President Reagan signed into law the Asbestos Hazard Emergency Response Act (AHERA) man dating the Environmental Protection Agency (EPA) to take certain actions to control asbestos hazards in schools. Dead lines were set for EPA to perform these actions: if they did not. so-called "ham mer clauses" in the bill took effect. One of these hammer clauses mandated the use of electron microscopy as a criterion for post-abatement clearance air monitoring. In response to AHERA. EPA convened a series of meetings under the negotiated t continued fnun puge 9) identify asbestos Fibers, and may there fore. give erroneously high resuits by in cluding other fibers, such as gypsum, min eral wood, or cellulose, from building products. Secondly, because of limited resolution small fitas with diameters less than -- .25 micrometers are not observed. These small fibers are believed to have major significance in carcinogenicity. By contrast, the TEM specifically iden tifies asbestos fibers and can resolve even the finest asbestos fibers that may be pres ent. How Does it Work? As in the case of phase contrast micros copy. samples of the airborne asbestos are collected by pulling air through a very fine filter, either a polycarbonate filter having a pore size less than or equal to .4 microme ters. or a mixed-cellulose ester filter hav ing a pore size less than or equal to .45 micrometers. Five samples are taken in the abatement area after the primary containment barriers have been removed, the abatement area has been thoroughly dried and it has passed visual inspection tests. These samples must rule-making process to formulate EPA's rules and re2ulations which implement AHERA. A subcommittee, or task force, of lead ing microscopists from both private and federal laboratories was responsible for producing a sampling and analysis proto col suitable for post-abatement clearance monitoring. The microscopists selected had extensive experience in both scanning electron microscopy (SEMI and transmis sion electron microscopy (TEM) for air borne asbestos analysis. The final rule defines TEM building be taken on a random basis in order to ade quately sample the air remaining in the containment are3. Similarly, five ambient samples must be taken outside the contain ment area, which are representative of the makeup air entering the abatement site. A sealed blank and two field blanks, one taken at one of the ambient sites and one taken in the containment area, complete the sample set. The samples are transported to the labo ratory where a direct preparation tech nique is required to produce a suitable preparation for TEM examination, it is important that the TEM used by capable of performing electron diffraction, that it have a flourescent screen with calibrated gradations for measuring fiber sizes, and that energy dispersive x-ray analysis, which provides information on chemical composition, be available. The combina tion of electron diffraction and energy dis persive x-ray analysis is used to identify libers or fiber structures as asbestos. Specific asbestos structures are identi fied in groups and are split into four class es: asbestos fibers, asbestos bundles, as bestos clumps, and asbestos matrices. The rule defines and illustrates each structure and further defines some detailed criteria clearance criteria which are based primari ly on a comparison of airborne asbestos levels outside the worksite or building The TEM method is operationally feasibk and the levels required for clearance ar< achievable using good asbestos abatemen procedures. Background Phase contrast microscopy (PCMl ha been used extensively in the past for asbes tos abatement clearance. However. PCM has two major limitations. First, it does noi (/`/titrinti#// W\ I bv which asbestos shall be identified. Be cause asbestos structures in small quanti ties are ubiquitous the blanks may comair asbestos structures introduced during filte manufacture, handling in the field, o" preparation and analysis in the laboratory Thus, the rule takes cognizance of this fac: and places a limit on the number of struc tures per square millimeter of filter sur face, which is considered to be statistical); indistinguishable from filter contamina tion. This criterion is expressed by scruc hires per square millimeter because thi contamination may originate from source other than the air being sampled and thu.< cannot be meaningfully expressed as . concentration per cubic centimeter of air How do I Pass or Fail? Under the present sampling require ments. at least 13 samples are collected fc the clearance testing and abatement site These include five abatement area sam pies, five ambient samples, two fief blanks, and one sealed blank. Not all thessamples, however, may need to be ana lyzed. The analysis stares with the fivabatement area samples. If the averag fiber content of those five samples is let fcontinued on page 121 CO --I o CD CO 1602-1 o oo APRIL 1988 ST008I 082 <continuedfrom page JO) than 70 structures per square millimeter of filter area, the samples are not significant ly different from background as defined earlier. Thus, they meet the clearance standard and it would be unnecessary to analyze the ambient or blank samples. The abatement area is cleared, the final con tainment barriers may be removed and the building may be reoccupied. If the average fiber count is more than 70 structures per square millimeter, there are two options; either the site may be recleaned or the blanks may be analyzed. If the blanks yield concentrations of fibers greater than 70 structures per square milli meter. there has been some contamination during the sampling or analytical proce dure. The contamination problem must be resolved and new samples must be collect ed and analyzed. If the blanks show concentrations less than 70 structures per square millimeter, then the five ambient samples are ana lyzed. The airborne asbestos concentra tions taken inside the containment barrier are then compared statistically with the air concentrations of the outside ambient air using a statistical test--the Z-test. If the abatement area samples are not signifi cantly different in concentration from the ambient control samples, the area meets the clearance criteria, the barriers come down, and the contractor leaves. If the abatement area samples are significantly higher than the ambient asbestos concen tration then the abatement area must be recleaned and the air sampling and analy sis procedure repeated. Figure 1 shows this procedure in the form of a flowchart. Can 1 Still Use Phase Contrast Microscopy? The answer to this question is a quali fied "yes." TEM is required under this rule for all major asbestos abatement pro jects. Major projects are defined as those where the area ofmaterial to be removed is greater than 2999 square feet or a linear pipe length of 999 feet. Phase contrast microscopy is permissible for projects which are smaller than this. TEM. howev er, will be phased in as a requirement for all projects. The phase-in will be per formed in two stages. TEM will be re quired 721 days after promulgation of the rule for projects where equal to or greater than 1500 square feet or 500 linear feet of asbestos are to be removed. TEM will be required for all asbestos abatement pro jects. regardless of size. 1081 days after promulgation of the rule. The pass-fail cri- 1602-2 terion for PCM on minor projects requires multiple samples, with clearance allowed only if all of the individual samples are below the limit of reliable quantification of the PCM protocol which is defined as 0.01 fibers per cc. Can I Pass? TEM clearance procedures have been appearing in specifications with increasing frequency over the last couple of years, and there is now a good body of data avail able to indicate that a contractor using good work practices throughout the entire abate ment project and a thorough multi-stage cleaning process can meet the TEM clear ance criteria. The importance of using good work procedures to control asbestos fibers throughout the entire project cannot be too highly stressed. These make the ultimate cleanup a more straightforward process with much higher probability of passing the final clearance. About the Authors Richard J. Lee is President, and Jan M. Stewart, Vice President of Project Devel opment, of Energy Technology Consultam (ETC), a leader in thefield of asbes tos determination. Jjee wasformerly head ofthe advanced electron microscopy group of USX Re search Laboratories and has over IS years' experience on determination of as bestos in water and air samples. He has participated actively in asbestos method ology workshops and task forces spon sored by the EPA, National Bureau of Standards, and the American Society of Testing Materials. He was a member ofthe select committee which prepared the transmission electron microscopy method ology for EPA's rules and regulations. Stewart wasformerly Vice President of McCrone Associates and McCrone Envi ronmental Services, Inc,, and has been an active participant in EPA, NBSandASTM workshops and task forces on asbestos methodology since J970. He is a past President ofthe National Asbestos Coun cil and a former Chairman of its Ethics Committee. Energy Technology Consultants (ETC) is a leader in thefield ofthe application of electron microscopy to problem solving. Jt has pioneered many advances in computer controlled electron microscopy and image analysis. ETC's TEM asbestos analysis group was responsible for preparing the final written drift submitted by the select committee to EPAfor the asbestos method ology to he used in final clearance. ETC has rcicntly opened a second electron mi croscopy luhoraion in Berkeley. Califor nia.