Document YrgvM3BErovZ0G9j1e42Z9pkV

n * * ion ai cemtft ro* JMAN AND INDUPPtlAL HEALTH 10U frAOADWAY CINCINNATI. OHIO 4S*0* DEPARTMENT OP HEALTH. EDUCATION, AND WELFARE PUBLIC HEALTH SERVICE ft OsM. January 17, 1968 REFER TO: ri.MN'iiKKsv.xmmi Dr. D. E. Ntckish Industrial Hygiene Specialist Ford Motor Company Ltd. Varle^ PrentwoodjEsscx.F.ngland Dear Dr. Hickishs Mr. Ayer has asked me to reply to your letter on brake lining deconposltlon. The enclosed draft of a report on brake decomposition euivnf.yuir.es sotne of the eatly work ve have done on this subject. Fuithet 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 hen shown 1t to contain mostly road dirt and rust with very few fibers. What fibers were released by the lining have apparently eace-ped into the air. However, soma other service garage operations, such as radius grinding and burnishing, which abrade the brake surface, will produce dust clouds containing free fibers slfoilar to '.hose found in brake lining manufacturing plants. To evaluate these situ ations 1 would recommend fiber counts on membrane filter ssoplrs as described lu the attached preprint by Edwards and Lynch. The British Occupational Hygiene Society has adopted limit of 2 fibere/cc longer than 5 ,ji. Some other articles which may be of interest are also enclosed. Please let me know If X can be of any further assistance. Sincerely youra, Fnr.losut.eti Jeremiah R. Lynch) Asst. Chief, Environmental Activities Field Studies Occupational Health Program 8006 1196 ' PRODUCED BY FORD SCF-FORD-0550