Document DDDXkMeZKo8rN5Jz7jDOLpnpB

NATIONAL CENTER FOR URBAN AND INDUSTRIAL HEALTH 1014 BROADWAY CINCINNATI. OHIO 4S20I DEPARTMENT OF HEALTH. EDUCATION. AND WELFARE PUBLIC HEALTH SERVICE January 17, 1968 REFER TO: Dr. D. 8. Hickish Industrial Hygiene Specialist Ford Motor Company Ltd. Dear Dr. Hickishi Mr. Ayer has asked me to reply to your letter on brake lining decomposition. The enclosed draft of a report on brake deconpositlon summarises some of the early work we hove done on this subject. Further work has generally confirmed the conclusion that brake linings give off very few free fibers except under extreme operating conditions. With regard to the cleaning of brake assemblies in service garages, electron micrographs of the dust removed from brake drums has shown it to contain mostly road dirt and rust with very few fibers. What fibers were released by the lining have apparently escaped into the air. However, some other service garage operations, such as radius grinding and burnishing, which abrade the brake surface, will produce dust clouds containing free fibers sitadlar to those found in broke lining manufacturing plants. To evaluate these situ ations 1 would recommend fiber counts on membrane filter samples as described in the attached preprint by Edwards and Lynch. The British Occupational Hygiene Society has adopted a limit of 2 flbers/cc longer than 5 ji. Some other articles which may be of Interest are also enclosed. Please let me know if I can be of any further assistance. Sincerely yours, Enclosures Activities Field Studies Occupational Health Program HFM- 005782 8006 1196