Document 3NbQjzg9r32O1xoZKZ502EyKD

Mr. Robert S. Magdelain, President Page 3 April 10, 1979 ttomarkB and Conclusions; The tests 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-blowing of brake drums ranged from 6.6 to 29.9 fibers/milliliter. However, when the Asbesto-Clene System was 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 42, 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 clotheB, This exposure had resulted in contamination of his clothes, re flected in the high residual asbestos concentration of 59,000 nanograms/cublc meter and 0.5 fibers/milliliter. In contrast, the operator in Test 41 and Test 43 wore dean coveralls. This points up the need to adhere to the 0SHA regulations concerning special clothing, change rooms, etc. to minimize 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. ANR:jm Arthur N. Rohl, Ph.D. Environmental Sciences Laboratory CAT-1020197