Occupational Exposure to Asbestos-Containing Gaskets During Air Conditioning Compressor Remanufacturing Study

By:

William E. Longo, Ph.D.

Richard L. Hatfield Michael D. Mount, CIH

Materials Analytical Services, Inc. Suwanee, Georgia

May 6, 2005

Occupational Exposure to Asbestos-containing Gaskets During Air Conditioner Compressor Remanufacturing Study

William E. Longo, Richard L. Hatfield, and Michael D. Mount

Materials Analytical Services, Inc., Suwanee, Georgia

Abstract

A work practice study was conducted involving the remanufacturing (rebuilding) of commercial grade air-conditioning (HVAC) compressors. The remanufacturing process requires work activities that include removal of compressor components with asbestos-containing gaskets used as seals at the connection points. For this work practice the asbestos gaskets were removed by hand scraping and the use of a pneumatic powered rotor abrasive pad for grinding and buffing. This study was performed to determine potential occupational asbestos exposure levels to mechanics that performed this type of work activities during HVAC compressor remanufacturing. The work practice was conducted inside an exposure characterization laboratory (ECL) and was performed by removing head and side cover gaskets from a Trane Model # 3F5B8O, 40-ton reciprocating compressor manufactured some time in the 1960s. Bulk analysis using the standard EPA methodology determined that the in place sheet gaskets had a chrysotile content of 55 percent by volume. The Addison & Davies protocol determined that, besides chrysotile, the gaskets also contained 0.11 percent by weight asbestiform tremolite. Pyrolysis Gas Chromatography Mass Spectroscopy (GCMS) of the polymer matrix determined that the material was chloroprene. Airborne asbestos levels were measured by phase contrast microscopy (PCM) and fiber identification verified by transmission electron microscopy (TEM) for both the personal and area samples collected during the study. The range of concentrations for the personal samples was 17.1 to 205.0 fibers/cc greater than 5 micrometers measured by PCM and all the fibers counted by PCM for the personal air samples were asbestos (fibers/bundles) as determined by the NIOSH 7402 method. Additionally, when free individual respirable asbestos fibers and bundles were examined by high-resolution field emission scanning electron microscopy (FE-SEM) no evidence of encapsulation was observed. Using the Addison & Davies preparation method on one air sample taken during the study determined an airborne tremolite concentration of 0.2 f/cc greater the 5 micrometers. All the tremolite fibers counted in the TEM were fibrous as defined by the Environmental Protection Agency counting rules. In this study, the airborne asbestos fiber levels measured in the ECL for both the mechanic and the helpers exceeded all current and historical Occupational Safety and Health Administration (OSHA) excursion limits and the 1972 permissible exposure limit (PEL) of 5.0 fibers/cc based on an eight-hour time weighed average (TWA) standard. The TWA was determined on the total time the investigators were inside the ECL.

2

This study demonstrates that the dry removal of asbestos-containing gaskets from HVAC compressor is a very significant source of respirable asbestos fiber exposure for both chrysotile and tremolite asbestos to the individual performing this activity and the work place environment.

UIntroduction Rubber based asbestos-containing gasket materials were manufactured and used in this country from around the 1930’s to the 1990’s.P

(1)P These types of gaskets typically

contain 60 to 80 percent chrysotile asbestos by weight. The remaining non-asbestos component of the gasket was usually constructed of a synthetic rubber material that usually consisted of either styrene butadiene rubber (SBR), chloroprene or a nitrile polymer P

(2-4)P.

Most companies replaced asbestos fibers in their gasket products with other non-asbestos mineral fibers in the late 1980’s or early 1990’s. This appears to coincide with the Environmental Protection Agency’s (EPA) 1989 ban on the manufacturing, importation, processing, and distribution of these types of products.P

(5)P However, the

United States Fifth Circuit Court of Appeals vacated most of the asbestos Ban and Phase Out Rule and remanded it back to EPA in October 1991. Although the court vacated and remanded most of the rule, it left intact the portion that regulated asbestos products that were not being manufactured, produced, or imported when the rule was published in November 1989. Since asbestos-containing gasket products were still being imported to and manufactured in this country during that time frame they were exempt from the ban and therefore, can still be manufactured, purchased, and used in this country today. Since asbestos gaskets can be legally used in the workplace today many workers still may be installing and removing asbestos-containing gaskets with little or no knowledge of the potential exposure problems associated with these types of products. Non-asbestos gaskets have been available for some time (late 1980’s) and should always be used in place of the asbestos gaskets. An article by Fowler in 2001 addressed this issue with these types of products when his research demonstrated that the cutting of asbestos gaskets had the potential to release respirable asbestos fibers well above current Occupational Safety & Health Administration (OSHA) standards.P

(6)P A recent

communication from OSHA’s Directorate of Enforcement Programs also recognized this problem when he stated that the use of asbestos-containing-gaskets can violate their current 0.1 f/cc PEL and are not exempt from labeling or removal standards as specified in 29 CFR 1926.1101 (8) (vi) (A) and 29 CFR 1910.1001 (J) (6) (i).P

(7)

Our asbestos research group was asked by the law firm of Waters & Kraus to examine the potential asbestos fiber exposure to Mr. Paul J. Sykes who was diagnosed with mesothelioma at the age of 64. A review of Mr. Sykes work history pointed to only one work practice that might have had the potential to expose Mr. Sykes to any significant levels of airborne asbestos fibers. This work practice involved the remanufacturing of

3

compressor units that require the removal of multiple asbestos-containing gaskets per unit during the rebuilds. Mr. Sykes founded the American Hermetics Company in 1974 that specialized in the remanufacturing of HVAC compressors. For approximately 15 years, starting in the early 1970’s, Mr. Sykes worked hands on rebuilding these compressors on a daily basis. His work practice would include the dry removal of gasket material from the metal flange surfaces by hand scraping and the use pneumatic powered rotor abrasive pad to buff the flange surface. A review of the peer-reviewed literature found very few published studies involving exposure assessments during the dry removal of asbestos-containing sheet gaskets from flange type metal surfaces P

(8-12)P. A review of these studies demonstrates that there

can be wide variability of fiber levels generated during the removal of asbestos-containing gaskets from metal flanges. The variability of fiber levels released is most likely dependent on the condition of the asbestos gasket, size of the gasket surface area and the method of removal.P

(12)P Another important criterion is the conditions (heat,

pressure, etc.) to which a gasket is subject to on the flange surface and the friability of the gasket. All these factors will impact the amount of fiber release during the removal process. P

PFurthermore, all these published studies were performed on elevated

pressure and elevated temperature steam lines and therefore may not be applicable to the conditions involving HVAC compressor gasket removal during the remanufacturing process. For this reason our research group decided to perform a gasket removal work practice study on an actual Trane compressor. This way we will have a better understanding of the potential exposure to airborne asbestos fibers that Mr. Sykes, as well as other compressor mechanics, may have had while rebuilding one of these units that contain asbestos gaskets. This study was performed to investigate the initial work activities in the remanufacturing of HVAC compressors. This process requires the removal of piston head covers, hand hole covers and other components with a gasket seal. A HVAC compressor mechanic (Mr. Jimmie Goodman) with approximately 40 years of experience performed the gasket removal activities used in this study. The work conditions (i.e. tools and removal methods) were determined and implemented solely by Mr. Goodman. Mr. Goodman stated that he was an employee of Mr. Sykes for the last 34 years and not only has performed this work practice on numerous occasions, but observed Mr. Sykes using the same procedures when he rebuilt HVAC compressors. Another aspect of this project was to determine that if there were a significant release of chrysotile fibers during the gasket removal phase would tremolite asbestos also be detected in the air samples. Pervious work by our group has shown that typical chrysotile containing-gaskets also contain trace amounts of tremolite in concentration of approximately from 0.1 to 0.001 weight percent. At these concentrations the tremolite is not detectable using the standard Environmental Protection Agency PLM and TEM techniques. It was only after the use of the Addison & Davies method, which was specifically designed to make this determination, that tremolite was found in chrysotile-containing gaskets in our earlier unpublished work. P

(13) POne air sample was collected in

this study that was specifically designed for trace tremolite analysis.

4

High intensity lighting and videotaping techniques were used inside an exposure characterization laboratory (ECL) during this study to visually document the pathway of exposure during the gasket scraping and grinding work activities. Previous studies and protocols have shown that the use of, what is commonly referred to as, the “Tyndall light phenomena” is an effective method of displaying microscopic airborne dust generated from work place activities.TP

PTP

(14-18) P The videotaping of this process can also be used as a

training tool in visualizing the importance of industrial hygiene controls for mechanics who remanufacture HVAC compressors.

UMaterials and Methods UTrane Compressor & Standard Bulk Analysis An originally equipped Trane Model # 3F5B8O, serial no. R67M-08A-1120 40-ton, 40 hp reciprocating compressor 40 ton/40 hp, circa 1960’s was used in this study. The Trane compressor was provided by Mr. Sykes and was delivered to MAS form his Atlanta Shop. Prior to the study one valve cover on the compressor was removed and a small sample of the gasket was collected to determine if that particular gasket was asbestos-containing to provide an indication of the asbestos content for all the gaskets present on the compressor. During the study itself the removal gasket material was collected from each valve cover or flange component to confirm that all the gaskets were in fact asbestos-containing. Asbestos types and amounts were determined by stereo and polarized light microscopy (PLM). P

(19) P Gas chromatography mass spectroscopy

(GC/MS) with pyrolysis was used to confirm the chemical composition of the polymer matrix of the gaskets.

UExposure Characterization Laboratory The use of exposure laboratories or containment areas to determine asbestos release under controlled conditions has been described extensively elsewhere in the peer-reviewed published literature.P

(6,11,12)P Briefly, the description of the ECL used in this

study is as follows: the ECL was constructed as a containment area to prevent the release of asbestos to the outside environment. The dimensions of this containment area were 6.0 m (length) x 4.5 m (width) x 2.4 m (height). The ECL also contained two viewing ports for videotaping purposes and had a decontamination area for the removal and disposal of contaminated clothing, an air lock for sample removal, and showers for decontamination of equipment and personnel. Fresh air inside the ECL was produced by a high efficiently particulate absolute (HEPA) filtered negative air machine (Force Air 2000 EC) and pulled through the ECL at a ventilation rate of 6.1 cubic meters per minute which equals an air exchange rate of approximately 5.8 times per hour (ACH) during the work practice. Before the study, the ECL was decontaminated by HEPA vacuuming and wet wiping. Also, all inside surfaces inside the ECL were repainted after the decontamination procedure.

5

UTyndall Lighting Three high intensity lights (750 watts Altmann 360Q) were used inside the ECL during the videotaping of the work practice to document dust generated by various tasks and to observe pathways of exposure to respirable dust. The mechanic and his assistant performed these studies wearing normal work clothes over disposable protective suits and were equipped with supplied air respiratory protection. The entire study was video taped with two Sony Handicams. UPCM & TEM Air Sampling Protocol Personal and area air samples were collected during the studies using non-conductive three-piece cassettes. The cassettes contained mixed cellulose ester (MCE) filters that were 25 millimeters in diameter and had a 0.8-micrometer (µm) pore size. These filters rested on a backing filter (5.0 µm pore size). Air sampling pumps were calibrated before and after the completion of the study by a DryCal primary flow meter. Area samples were collected using high volume rotorary vane air sampling pumps (i.e. Dawson 110 volt). A flow rate of 10 liters per minute (lpm) was used for the background area samples collected prior to starting work activities. A flow rate of approximately 1.5 lpm was used for the area samples during the study. The four area samples were located in four equidistant quadrants at a distance of approximately 2.1 meters from a workbench placed in the center of the ECL. The area sample cassettes were placed on sampling stands at a height of approximately 1.5 meters. The four calibrated high volume air-sampling pumps were placed outside the chamber and each pump was connected to an area air cassette by plastic tubing passing through the wall of the ECL. The two investigators (mechanic and helper) performing the study were each fitted with three personal Gilian air sampling pumps calibrated to 0.5 lpm. The air sampling cassettes were placed within their breathing zones attached to each shoulder. The air samples were collected in general accordance with the NIOSH 7400 method. P

(20)P Ten

air-sampling cassettes were opened for 30 seconds each inside the ECL during the study to serve as field blanks. The flow rate of 0.5 1pm was used to avoid overloading of the air filters. The Trane compressor has seven gaskets that were removed during the study. These included four head piston covers, two hand holes and one bell cover. One air sample set (worker and helper personals and area air samples) was taken for each gasket removed for a total of seven air sample sets. The removal of each gasket took approximately 4 to 5 minutes of time. After each gasket was removed the personal and area pumps were shut off and the air samples exchanged inside the ECL. The air pumps were all restarted and the next gasket was removed. Each air sample exchange time was approximately 7 to 8 minutes. One additional set of area samples (A-8) was collected after gasket number seven removal was completed.

6

URemoval of HVAC Components and Asbestos-containing Gaskets A Trane Model F-80 (circa 1960’s) compressor supplied by Mr. Sykes was used for this study. According to the mechanic the compressor had not been rebuilt or remanufactured and thereafter still contained original parts and components. Photographs of the compressor are shown in Figures 1 through 4. As described earlier Mr. Jimmie Goodman performed all the actual work activities including the removal of gasket material in the ECL. The mechanic described this work activity as the one that he performed on numerous occasions at the shops where he worked during his career and observed Mr. Sykes performing as well. This work practice consisted of using a pneumatic ratchet and socket (air hammer, 90 psi) to remove the nuts, a hand held hammer to dislodge the compressor valve/flange components, a putty knife to scrape the exposed gasket surfaces and a small pneumatic grinder (90 psi) to remove residual gasket material adhering to the surface and to polish the flange face with a Carborundum abrasive pad. The mechanic stated this procedure would usually take one to two hours per compressor. The compressor mechanic supplied his own tools used during the study and are shown in Figures 5 & 6. All photographs taken of the Trane Compressor and the tools used in this study can be found attached to this report in Appendix A, Section 10. UPCM, TEM Air Sample & Fabric Analysis All air filters collected (except for the FE-SEM samples and trace amphibole air sample) were analyzed by PCM in general accordance with the NIOSH 7400 method using the “A” counting rules.P

(20)P Additionally, representative air samples were further analyzed by

TEM in general accordance with the NIOSH Method 7402 “Asbestos Fibers by TEM”.P

(21) P For quality control, 10% of the PCM samples were blind recounted by the same

PCM microscopist and an additional 10% were sent to an independent laboratory (Wisconsin Occupational Health Laboratory) for analysis. Cloth swatches from the work clothing worn by the mechanic and helper during the study were analyzed by the recommended EPA method.P

(22)

UFE-SEM Analysis Surface morphology of the airborne chrysotile fibers and bundles collected after the completed gasket removal activities were examined using a Hitachi S-4700 field emission scanning electron microscope (FE-SEM). Photomicrographs were taken of the fibers at magnifications between 10,000 to 150,000 times to determine the presence or absence of synthetic rubber coatings (encapsulation) on the fibers. These air samples were collected on a 25 millimeter (0.4 micrometer pore size) polycarbonate filters placed on a backing pad in the air filter cassettes. These air samples were collected with personal sampling pumps calibrated to a flow rate of 0.5 lpm and were positioned in the breathing zone of the helper. This set of personal air samples was collected after the last gasket was removed from the compressor in the study. The air filter was examined

7

by the “direct” method. The filter surface was coated with 100 angstroms of metal before examination in the FE-SEM.

UTrace Amphibole Bulk and Air Filter Analysis UTremolite Bulk Sample Analysis For trace amphibole bulk asbestos analysis the Addison & Davies method was used.P

(13)

PThe analytical procedure is described in their paper but briefly the method is as follows: Approximately 10 grams of a composite from the seven gaskets removed during the study are weighed into a porcelain crucible and ashed for 18 hours at 480 degrees CP

oP

as described by EPA/600/R-93/116 ashing method. P

(19) PThe ashed sample is finely

shredded and 2.5 grams are weighed into a previously tested boiling flask. 80 milliliters of 2N sulfuric acid is added to the flask and connected to a new condenser column and boiled for one hour with stirring. The sample is cooled and transferred to centrifuge tubes and centrifuged at 2300 RPM for 30 minutes. The pellet is transferred back to the boiling flask using 80 milliliters of 4N sodium hydroxide and connected to the condenser column and boiled for one hour with stirring. The sample is again cooled and transferred to centrifuge tubes and centrifuged at 2300 RPM for 30 minutes. The sample is transferred from the centrifuge tubes into a pre-weighed plastic Petri dish and dried overnight at 70 degrees CP

oP in a drying oven. The dish plus dry sample are

reweighed to determine the amount of sample remaining after chrysotile digestion. The dry sample is prepared and analyzed by TEM to determine weight amount of amphibole present as described by the EPA TEM bulk analysis protocol. P

(19)P

UTremolite Air Sample Analysis To determine if amphibole fibers were released from the chrysotile gaskets during the actual removal activity one air sample was collected as follows: Area air sample (A-1-E) was collected during the work practice study and had a total air volume of 259 liters. The collected MCE air filter was analyzed by the Addison and Davies Method and was prepared as follows. The MCE filter was placed in a previously tested boiling flask and one milliliter of concentrated nitric acid is added and then heated on a hotplate to dissolve the filter. A new Teflon stir bar is placed in the flask. 80 milliliters of 2N sulfuric acid is added to the flask and connected to a new condenser column and boiled for one hour with stirring. The sample is cooled and transferred to centrifuge tubes and centrifuged at 2300 RPM for 30 minutes. The supernatant is removed using a plastic transfer pipette leaving approximately 5 milliliters in the tubes. The samples are transferred back to the boiling flask using 80 milliliters of 4N sodium hydroxide and reconnected to the condenser column and boiled for one hour with stirring. The sample is again cooled transferred to centrifuge tubes and centrifuged at 2300 RPM for 30 minutes. The supernatant is removed as previously described and the remaining solutions in the tubes are diluted to 40 ml with filtered water. This is then filtered through a 25 mm MCE (0.8 micrometer pore size) filter and dried overnight. The filter is

8

prepared and analyzed by TEM as described by the EPA Level II protocol.P

(23)P Results

were reported as fibers or per cc. The protocol followed for the work practice study and the interview notes from Mr. Goodman can be found attached to this report in Appendix A, Section 1.

UResults It was determined by PLM that each of the gaskets (seven) removed during the study contained 55% chrysotile asbestos (Table 1). The GC/MS analysis determined the rubber gasket material was constructed of chloroprene.

Additionally, a bulk gasket sample (composite consisting of approximately equal amounts of each) of the removed gasket samples was prepared by the Addison & Davies procedure and analyzed by TEM to determine the weight percent of amphibole asbestos. The result of this analysis determined that besides chrysotile the gaskets also contained 0.11% tremolite asbestos by weight (Table 2). All laboratory data sheets for the bulk analysis can be found attached to this report in Appendix A, Section 3. Tables 3 and 4, respectively; illustrate the PCM 7400 and TEM 7402 results for this study. The mechanic had a peak exposure of 205.0 fibers per cubic centimeter (f/cc) and an 8-hour TWA exposure of 12.0 f/cc. The investigator designated as the helper had a peak exposure of 100 f/cc and an 8-hour TWA exposure of 7.0 f/cc. The area samples had a range of 7.3 f/cc to 41.1 f/cc. The calculations for the TWA, air sampling times and geometric mean for the air sample results are shown in Table 5. All laboratory data sheets for the PCM 7400 and TEM 7402 methods can be found attached to this report in Appendix A, Sections 4 and 5 The one high volume area sample (A-1-E) analyzed by the Addison & Davies method did detect airborne amphibole fibers. The tremolite concentration for this sample was 1.1 fibers/cc for all fiber sizes and a concentration of 0.2 fibers/cc for tremolite fibers greater than 5 micrometers in length (Table 6). Figures 7 and 8 show typical tremolite fibers found in the air sample analysis. The data sheets for the Addison & Davies air sample analysis are located in Appendix A, Section 6 of this report. The results of the fabric sample are shown in Table 7 and show that the clothing worn by the investigators had an asbestos contamination level of between 6.9 X 10P

4P to 1.0 X

10P

6P asbestos structures per cmP

2P. All laboratory data sheets for the EPA fabric analysis

can be found in Appendix A, Section 8. Both the in house PCM blind recounts and the results from the independent laboratory verified that the PCM data reported for this study were valid and had an acceptable rate of error. The PCM count sheets for all the QA/QC analysis as well as the reported error rates for this study can be found in Appendix A, Sections 7 of this report.

9

The SEM analysis of the airborne chrysotile fibers and bundles did not demonstrate rubber coatings on the free respirable asbestos structures and are shown in Figures 9 through 12. All the micrographs taken by the FE-SEM are located in Appendix A, Section 9 of this report.

UDiscussion The air samples collected in this study were analyzed by both the NIOSH Method 7400 “Asbestos and Other Fibers by PCM” and the NIOSH Method 7402 “Asbestos Fibers by TEM”. The method of preparation for all of these samples was by the direct method. Because of the possibility of overloaded samples during the work activity very low air sampling volumes were implemented in this study. This strategy was successful in that only two of the 70 area and personal air samples collected in this study were slightly outside the required 100 fibers mmP

2P to 1300 fibers/mmP

2P filter loading range. Sample P-

2-F had a fiber loading of 99.4 f/mmP

2P and P-3-A had a fiber loading of 1331.2 f/mmP

2P.

Even though these two samples were less than 1% outside of the required range NIOSH requires that these samples are to be labeled as having a greater than optimal variability and are probably biased if these samples were to be used in compliance air monitoring. However, for sample P-3-A, it is well understood that high fiber loadings on air filters (greater than 1300 f/mmP

2P) will only biased the reported results to lower fiber

concentrations.P

(25,26) PSo the fiber concentrations found on this one sample can only be

viewed as a conservative estimate for the measured airborne level. The TWA calculated for both the mechanic and the worker were based on the asbestos exposures in the ECL. This work practice study was done under controlled conditions and was not designed to replicate the work environment at any of Mr. Sykes job sites. The ECL has, of course, a smaller volume of air and most likely a different ventilation rate then Mr. Sykes work sites. These two factors would likely affect the asbestos exposure levels that Mr. Sykes would have had performing the work practices that we studied. However, because of the magnitude of the fiber levels that we measured, we believe that Mr. Sykes peak exposures would clearly have been over the 1972 excursion limit of 10 fiber/cc each time he would have removed asbestos-containing gaskets using these work practices on the types of HVAC compressor that we studied. Also, it is our belief that on some occasions Mr. Sykes TWA could have been above the 1972 OSHA PEL of 5.0 fibers/cc. A comparison of the air data collected from the PCM analysis showed that one set of air samples (P-3 and A-3) had asbestos fiber levels 4 to 6 times higher than the other six sample sets measured during the study. We believe that this higher level is a direct result from the type of work activity that the mechanic performed while removing this set of gaskets. In this study seven gaskets were removed during the work activity. Except for gasket #3 (P-3 and A-3 air sample set) the other six gaskets were removed with both scraping and grinding work procedures. For gasket #3 there was no scraping activity only grinding and buffing. Because there was only grinding on gasket #3 this procedure took almost twice as long (approximately 2 minutes) as with the other six gaskets (approximately 1 minute). A review of the video tape taken the work practice confirms

10

this observation. A longer grind time, as observed in the removal of gasket #3, would be expected to generate higher airborne asbestos fiber levels. The actual time required for both the scraping and grinding activities is shown in Table 8. The PLM bulk analysis of the compressor gaskets and the NIOSH 7402 method TEM air sample analysis found only chrysotile asbestos. No tremolite was observed for the samples that were analyzed by these two common methods. However, it has been well recognized that chrysotile can be contaminated with trace amounts of tremolite and this amphibole may then be a contaminate of the corresponding chrysotile containing products. To determine if trace amphiboles are present in samples such as these (chrysotile-containing compressor gaskets) additional analytical techniques are required to over come the analytical sensitivity problems associated with the EPA PLM and NIOSH 7402 methods.P

(24)P In this study we used the Addison & Davies method that was

specifically designed to detect trace amounts of tremolite in chrysotile asbestos.P

(13)P

This method works by digesting the chrysotile present in the sample thereby lowering the detection limit for tremolite from about 0.5 % in a typical bulk sample to approximately 0.0001%. The same concept holds true for air samples, that is, by removing the chrysotile from the air sample filter before the TEM analysis increases the sensitivity for tremolite. Therefore, if amphibole fibers are present in the air samples then the tremolite might be detected with routine TEM analysis. Area sample A-1-E was collected for the detection of airborne tremolite. The air sample was run during the entire work practice so as to collect significant amounts of airborne gasket dust. An air sample with this much air volume collected in a dusty environment would normally be too overloaded to be analyzed by either routine light or electron microscopy. However, using the Addison & Davies sample preparation procedure most of the non-asbestos matrix material and chrysotile asbestos fibers are removed before the routine analysis by TEM. After removal of the interfering materials a routine TEM analysis counted 100 tremolite fibers with a detection limit of 0.011 fibers/cc. Typical micrographs tremolite fibers found in the air sample we analyzed are shown in Figures 7 and 8. The high resolution FE-SEM analysis undertaken in this study demonstrated that many of the free respirable fibers and bundles found in the air samples did not contain a synthetic rubber coating and therefore were not encapsulated. There was however some fiber matrixes that consisted of asbestos fibers protruding from chloroprene particulates. The findings of asbestos matrixes along with repirable bundles and fibers are common with all types of asbestos products that we have tested in the past. Micrographs of typical uncoated chrysotile fiber and bundles are shown in Figures 9-12. These FE-SEM observations demonstrate that the rubber matrix in the gaskets is not encapsulating the majority of the chrysotile fibers and bundles that are released during the grinding process. This is collaborated by the formulations for sheet gaskets which call for 60 to 80% chrysotile and 20 to 40% synethic rubber. This ratio of synthetic rubber to asbestos does not provide enough rubber material to coat each and every fiber or bundle of asbestos present in the sheet gasket product. Asbestos-containing

11

sheet gasket products should not be viewed as “encapsulated” but as a mixture of two components where the synethic rubber material provides a framework for holding the asbestos fibers together in a sheet form. Therefore, when sufficient energy is applied to the gasket (i.e. scrapping and grinding) it now becomes a friable material releasing airborne dust that contains non-coated/non-encapsulated respirable asbestos fibers. This is understood by the EPA’s classification of asbestos sheet gasket as a Category 1 non-friable material that has become friable due to either sanding, grinding, cutting or abrading. The results form the fabric samples (Table 7) showed that the clothing worn by the individuals in this study were contaminated and pose additional exposure problems to Mr. Sykes throughout the work day. Additionally, asbestos exposure would have occurred for both Mr. Sykes and his family members if the clothes are worn from his workplace and taken home for laundering. P

(27)

UConclusion

Our data shows that the dry gasket removal methods used by Mr. Paul Sykes and his employees resulted in a very significant occupational exposure to airborne chrysotile and tremolite asbestos fibers during the initial steps of the compressor remanufacturing process. Based on the air sample data in this study it is clear to us that Mr. Sykes work practices during the compressor remanufacture process would routinely exposed him to airborne asbestos fiber levels above the 1972 OSHA excursion limit of 10 fibers/cc and, on some occasions, may exceed the 1972 OSHA PEL of 5 fibers/cc on a time weighted average. Besides the high airborne chrysotile exposures Mr. Sykes would have also been exposed to significant amounts of amphibole asbestos (tremolite) that commonly is present as a contaminant in the chrysotile mines. By the manufacturer adding chrysotile to their gasket formula they are in fact contaminating that gasket with tremolite fibers. During the removal process our data shows that not only are chrysotile fibers released into the breathing zone of the worker, but tremolite fibers as well. Based on our earlier work, and the results found here, it is our opinion that any individual who is exposed to asbestos-containing products that were manufactured with Canadian chrysotile has a high potential to be exposed to airborne tremolite fibers along with the chrysotile. The results also show, that besides Mr. Sykes and his employees receiving high asbestos exposure levels, that other mechanics working on asbestos-containing gaskets products and using these types of work practices, will have the potential for significant exposure to airborne asbestos levels. At any current job site if the compressor gaskets are determined to contain asbestos, we recommend that the workers should take all precautions to prevent exposure to asbestos fibers and use other available manufacturers of non-asbestos-containing gasket products when available. Under no circumstances should asbestos-containing gaskets be subjected to any type of scraping, grinding or sanding without complete dust controls because of the

12

large amount of respirable asbestos fibers or fibrous dust that can be produced during this process. Even with non-asbestos-containing gasket products, this practice should be discouraged. This study concludes that high levels of airborne asbestos fibers can be generated during the removal of asbestos-containing gaskets from a HVAC compressor. The variability of the fiber levels found in the study was dependent on the method of removal. That is as grinding time was increased fiber levels increased. These findings are consistent with a previous publisher study by Longo et al, involving gasket removal from steam lines. P

(12)P The data present here also shows that the type of equipment

these sheet gaskets are attached to makes little difference if airborne fibers will be released during their removal. The results found in this study with a HVAC compressor were similar to published fiber released valves involving elevated temperature and elevated pressure steam lines. P

(10,12)P We also conclude that the most important factor

effecting the asbestos fiber release during the removal process is dependent on how tightly adhered to the flange face and how that gasket is removed (scraping vs. grinding) and not what type of mechanical system the gaskets are being removed from. Based on this information and work by others, standard industrial hygiene protective measures such as notification, training, local exhaust engineering controls, and personal protective equipment should be utilized when removing asbestos-containing sheets gaskets from compressors similar to the one used in this study as well as with any other type of system that contains asbestos-containing gaskets.P

(6,10-12)P

UAcknowledgements

This study was funded in part by plaintiff’s action involving occupational exposure to asbestos by HVAC compressor mechanics. Also we would like to thank Dodie Teasley for her help with this manuscript and the analyst at MAS who worked on this project.

13

UREFERENCES 1. Bowler, W.J.; Hows and Whys of Packing of Gaskets, Paper Trade Journal.

Oct. (1965).

2. Garlock Industrial Products Catalog. (1969).

3. Klinger Compressed Gasket Materials Catalog. (1983). 4. Crane Packing Company. Catalog 60-R-2 (1954).

5. Environmental Protection Agency (EPA): 40 CFR Part 763. Asbestos:

Manufacture, Importation, Processing and Distribution in Commerce Prohibitions; Final Rule. Title 40, Code of Federal Regulations, Part 263, Fed. Reg. 54(132), July (1989).

6. Fowler, D.P.; Exposure to Asbestos Arising from Band-sawing Gasket

Material. Appl. Occup. Environ. Hyg. 15(5): 404-408 (2000).

7. December 22, 2003 letter from Richard E. Fairfax, Directorate of Enforcement Programs of OSHA to Mr. Fred Boelter of Boelter and Yates. A copy of this letter can be viewed at the OSHA website, HTUwww.OSHA.govUTH, search keyword Boelter

8. Cheng, R.T.: McDermott, H.J.; Exposure to Asbestos from Asbestos

Gaskets. Appl. Occup. Environ. Hyg. 6 (7): 588-591 (1991).

9. McKinery, W.N.: Moore, R.W.; Evaluation of Airborne Asbestos Fiber Levels During Removal and Insulation of Valve Gaskets and Packing. Amer. Indus. Hyg. Assoc. J. 53(8): 531 – 532 (1992).

10. Millette, J.R.: Mount, M.D.: Hays, S.M.; Releasability of Asbestos Fibers

from Asbestos-containing Gaskets. Environ Choices – Tech Supp. 2:10 – 15 (1995).

11. Boelter, G.W.: Crawford, F.N.: Podraza, D.M.; Airborne Fiber Exposure

Assessment of Dry Asbestos-Containing Gaskets and Packings Found in Intact Industrial and Maritime Fittings. Amer. Indus. Hyg. Assoc. J. 63(6) 732-740 (2002).

12. Longo, W.E.: Egeland, W. B.: Hatfield, R.L.: Newton, L.R.; Fiber Release

During the Removal of Asbestos-Containing Gaskets: A Work Practice Simulation. Appl. Occup. Environ. Hyg. 17 (1) 55-62 (2002).

13. Addison, J.: Davies, L.; Analysis of Amphibole Asbestos in Chrysotile and

Other Minerals. Am. Occup. Hyg. 34(2): 159 – 179 (1990).

14

14. Environmental Protection Agency Standard Operating Procedure. EPA-Libby-

02, March (2001). 15. MDHS 82, The Dust Lamp, Health & Safety Executive, March (1997). 16. Chambers, D.T.; Dust Control Development In: Asbestos, s.: Chissick, R.;

Eds. Vol. 2, Properties, Applications and Hazards, pp. 193-211, John Wiley & Sons, New York (1983).

17. Selikoff, I.J.; Insulation Hygiene Progress Report. 3 (4): Winter (1971).

18. Lee, G.; Removing Dust from Brake Assemblies During Vehicle Servicing –

Alternative Cleaning Methods. Am. Occup. Hyg. 13; 33-36 (1970). 19. Environmental Protection Agency (EPA): Method for the Determination of

Asbestos in Bulk Building Materials. EPA/600/R93-116. EPA, Washington, D.C. (1993).

20. National Institute for Occupational Safety and Health (NIOSH): Asbestos and

other Fibers by PCM-Method 7400. (NIOSH) Publ. No. 94-113, NIOSH, Cincinnati, OH. (1994).

21. National Institute for Occupational Safety and Health (NIOSH): Asbestos by

TEM-Method 7402. NIOSH Issue 2, 15 Cincinnati, OH (1994).

22. Chatfield, E.J.; Analytical Protocol for Determination of Asbestos Contamination of Clothing and Other Fabrics. Microscope 38: 221-22 (1990).

23. Environmental Protection Agency (EPA): Methodology for the Measurement

of Airborne Asbestos by Electron Microscopy. EPA Draft Report, Contract No. 68-02-3266. EPA, Washington, DC (1984).

24. Williams–Jones, E.: Normand, C.: Clark, P.: Vail, H.: Martin, F.R.; Controls of Amphibole Formation in Chrysotile Deposits: Evidence From Jeffrey Mine, Asbestos, Quebec. The Health Effects of Chrysotile Asbestos: Contribution of Science to Risk Management Decisions, Can Mineral Spec. Publ. 5: 89-104 (2001).

25. Chen, C.: Yu, T.: Shih, T.: Baron, P.; Computer Simulation of Particle

Overlap in Fiber Court Samples. Amer. Indus. Hyg. Assoc. J. 62(3) 281-287 (2001).

26. Knight, G.; Overlap Problems In Counting Fibers. Amer. Indus. Hyg. Assoc.

J. 35:113-114 (1975).

15

27. Comments of Johns-Manville Corporation with respect to Notice of Proposed Rulemaking Occupational Exposure to Asbestos. (Federal Register, October 9, 1975). To: Occupational Safety and Health Administration, U.S. Department of Labor, April 1976.

16

TABLE I PLM Analysis of Trane HVAC Compressor Gaskets

Sample Asbestos Type Concentration of Chrysotile Volume Percent

Gasket Samples 1-7 Chrysotile 55%

TABLE 2 Addison & Davies Analysis of Bulk Gasket Samples

Sample Asbestos Type Concentration of Tremolite Weight Percent

Gasket Samples 1-7 Tremolite 0.11%

TABLE 3 Removing Gasket Material from HVAC Compressors

PCM NIOSH 7400 Airborne Exposure Levels Sample Type No. Of Air

Samples Analyzed Range (f/cc)

Background 5 <0.001 Worker 21 18.0 – 205.0 Helper 21 17.1 – 100.0 Area 28 7.3 – 41.4 Field Blanks 10 <7 f/mmP

2P

Total air sampling time for the personal and area sample sets = ~5 (4 to 8) minutes

TABLE 4 Removing Gasket Material from HVAC Compressors

TEM NIOSH 7402 Analysis Sample No. Sample Type % Asbestos

M35258-003 Background 0.0 M35258-012 Personal 100 M35258-022 Personal 100 M35258-028 Personal 100 M35258-032 Personal 100 M35258-035 Personal 100 M35258-047 Area 71.4 M35258-055 Personal 100 M35258-081 Field Blank 0 M35258-090 Field Blank 0

17

TABLE 5 PCM TWA Calculations

Personal Air Samples (Mechanic)

Series No. Sample Description Geometric Mean Fibers/cc

Sample Run Time Minutes

P-1-A through C Personal JG 66.0 5 P-2-A through C Personal JG 30.7 4 P-3-A through C Personal JG 164.4 5 P-4-A through C Personal JG 26.3 8 P-5-A through C Personal JG 30.9 5 P-6-A through C Personal JG 20.7 5 P-7-A through C Personal JG 88.2 5

Total 37 Sampled Duration TWA (32 min.)= 59.0

Work Duration TWA (98 min.)= 58.6 8-hour TWA (480 min.)= 12.0

Personal Air Samples (Helper)

Series No. Sample Description Geometric Mean Fibers/cc

Sample Run Time Minutes

P-1-D through F Personal RH 21.2 5 P-2-D through F Personal RH 25.8 4 P-3-D through F Personal RH 81.7 5 P-4-D through F Personal RH 20.8 8 P-5-D through F Personal RH 30.9 5 P-6-D through F Personal RH 23.8 5 P-7-D through F Personal RH 42.6 5 P-8-D through F Personal RH

Total 37 Sampled Duration TWA* (32 min.)= 34.3

Work Duration TWA** (98 min.)= 38.2 8-hour TWA*** (480 min.)= 7.0

* TWA calculated using the geometric mean of the samples from each series and the actual sampling time ** TWA calculated using the geometric mean of the samples from each series and the time elapsed between cassettes (I.e. Assumed Exposure Time). *** TWA calculated using the geometric mean of the samples from each series and the time elapsed between cassettes averaged over 480 minutes with no exposure assumed over the remainder of the 8-hour period.

18

TABLE 6

TEM Analysis of Addison Davies Preparation Sample No. Sample Type Fibers/cc >5

um Asbestos Type

M35259-001 Area 0.2 Amphibole- Trem/Actin

TABLE 7 TEM Fabric Dust Contamination Levels

Sample No. Sample Type Asbestos Fibers/cmP

2 PDetected

M35259-001 Helper Shirt Fabric 6.88 x 10P

4P

M35259-002 Helper Pants Fabric 1.05 x 10P

6P

M35259-003 Worker Shirt Fabric 2.47 x 10P

5P

M35259-004 Worker Pants Fabric 9.33 x 10P

5P

M35259-005 Background Shirt Helper 0.0 M35259-006 Background Pants Worker 0.0

Table 8 Scraping and Grinding Times For Each Gasket Removal

UGASKET #U UACTIVITYU UACTIVITY DURATIONU

Gasket 1 Hand Scraping 1:12 Minutes

Power Wire Brushing 1:14 Minutes (2:05 between start &

finish due to hose uncoupling) Gasket 2 Hand Scraping 0:57 Minutes

Power Wire Brushing 1:06 Minutes Gasket 3 Hand Scraping 0:00 (No Scraping)

Power Wire Brushing 2:46 Minutes Gasket 4 Hand Scraping 2:30 Minutes

Power Wire Brushing 1:05 Minutes Gasket 5 Hand Scraping 2:24 Minutes

Power Wire Brushing 1:08 Minutes Gasket 6 Hand Scraping 1:33 Minutes

Power Wire Brushing 1:39 Minutes Gasket 7 Hand Scraping 2:03 Minutes

Power Wire Brushing 1:59 Minutes

19

20

21

22

23

24

25

26