Document vy0Z3gyjpww2nvy76O6gLBrj9

ivT*****.-*^ VV THE MOUNT SINAI MEDICAL CENTER ONE GUSTAVE L LEVY PUCE NEW YORK N Y 10029 N1LFISA op: Mount Sinai School of Meducme 'The Mount Sinai Hospital P- April 11, 1979 Mr. Robert S. Magdelain, President Nilfisk af America, Inc. 201 Kina Manor Drive King of Prussia, Pennsylvania 19406 SnuinvtmentaJ Science# Lafeoraier? Gumming* floeic Science# Bui/ding JC oj( JOS Street Nets York, JSeitf York 1002$ (212) 6S0-G173 Dear Mr. Kagdal&ln: This will report the results of air sampling tests conducted, la October 1978, to determine chrysotile asbestos concentrations dur ing brake repair wart. Our major objective was to determine the efficiency of the Kilflsk Asbestos System utilizing HEPA filters, particularly with regard tD submierostopic asbestos fibers. Studies conducted in our Laboratory and elsewhere have demonstrated that free asbestos fibers present in brake drum dusts are predominantly shorter than 5ym in length. In particular. It was found that about 751 of the fibers in such dusts were less than 0.3um in length, as determined by transmission electron microscopy. Thus, the optical microscopic technique used by DSHA for determining asbestos levels in workplaces (In which only fibers Sum or longer are counted) would overlook a large number of asbestos fibers in air samples. That la. the total asbestos exposure in terms of fiber number, mass and surface area would be significantly greater than the levels determined using the OSHA fiber'-counting method. ' Therefore, it was of considerable interest to us to have an oppor tunity to test the efficiency of the Nilfisk Ashesto-Clene System, To do this personal air sampling was carried out on the exhaust of a HEPA-filtered vacuum dust collector and, simultaneously, on a garage mechanic cleaning a brake drum with the NilfiBk brake en capsulation cylinder. Three such testa were made. Background air samples, also using personal air pumps, were taken. For each of the tests, a sample of settled dust was taken from the brake ,drum. The dusts were analyzed by m--ray diffraction in the step-- scan mode to quantitatively determine aabestoB contents, using a technique previously published. Asbestos was found in all three samples, ranging from 2.51 to 4.51 by weight. The membrane filters were analyzed by both transmission electron microacopy (125,000) and by the standard OSHA fiber-counting technique, employing phase contrast optical microscopy. The results ore as fellows: 105525 007912 PRODUCED BY FORD Mr, Robert S. Magdelain, President Page 2 April 10, 1979 Sample Deecription HanogTsas/eu meter Fibers/milliliter (electron microscopy) (optical microscopy) TEST il -l background (70 feet from operator) U-2 Operator (breathing rone - 6 ft. from dust collector) N-3 Dust collector (HEPA-filtered vacuum) 400 0 0 0 0 0 TEST #2 H-4 background (70 .feet ixom operator) N-5 Dust collector (HEPA-filtered vacuum) H-6 Operator (breathing tone - 6 ft. from dust collector) 615 0 59,000 0.12 0 0.5 TEST #3 M-4 background (same as in Test #2) B-7 Operator (breathing zone - 6 ft. from dust collector) H-8 Dust collector (HEPA-filtered vacuum) 615 0 0 0.12 0 0 007913 Mr. Robert S. Magdelaim, President Page 3 April 10, 1979 Remarks and Conclusions; The testa demonstrate that asbestos levels are virtually eliminated by the use of a system employing brake encapsulation device connected to a HEPA-filtered vacuum dust collector. Without the use of such equipment, fiber concentrations during compressed air jet-blovlag of brake drums ranged from 6,6 to 29.8 fibers/milliliter. However, when the Asbesto-Clene System vas used, fiber concentrations on both the mechanic and dust collector exhaust were not detected, as verified by transmission electron microscopy. An important exception to this is observed in Test #2, the sample taken on the operator. Prior to this test, this mechanic had worked on brake jobs without using the Asbesto-Clene System and without changing his work clothes. This exposure had resulted in contamination of his clothes, re flected is the high residual asbestos concentration of 39,000 nanograms/cubic meter and 0.5 fibers/milliliter. In contrast, the operator is Test #1 and Test #3 wore clean coveralls. This points up the need to adhere to the OSHA regulations concerning special clothing, change rooms, etc. to minimise contamination. The background asbestos measurements, of 400 and 615 nanograms/ cubic meter, are consistent with other background measurements taken during brake repair work. They are the result of residual contami nation of the garage by asbestos. This study has been unique and fortunate in two respects; first because of the great interest and importance of determining chrysotile asbestos levels in such circumstances. The data indicate that the Asbesto-Clene System represents an outstanding advancement in industrial hygiene procedures to control asbestos exposure- It has also been a pleasure to work with you in preparing and conducting these tests. If there are any questions regarding the results or conclusions in this report, please do not hesitate to contact me. A2JR: jm 087914 PRODUCED BY FORD