Document 0mLppXGG10GkjpGKkJx9Egox

FILE NAME: Z< DATE: DOC#: Z< DOCUMENT DESCRIPTION dZDZZZZ ZZ^ Hr. A. R. Clark I. O. 8:)X 2331, July 8, 1976 Hr. J. H. Lloyd. Dr. R. J. Sexton Hr. F. HilliaE1S Asbestos Expos21re l\ssociat_ed Hitb AutomotivE! Brake Systems At the request oE the Plant Nedical Departraent, measurements of personnel exposur.e to asbestos fibers during bra:Ze repair dnd inspect~ioQ job tasks have been E2.Ce. The spirit of cooperation on the part of Hr. L. M. Ho~fman ,ms commendable vhile "12ari!J.g p2rsonnel samplers curing three_ types of job tasks i~lvolving brake maintenance. Discussion of each of the job performances, together ,o;ith results is 35 fol1m-ls: FIRST: The Tight rear- \,Oheel of a pic.kup truck ,vas removed for irrspectLon. It was deten"Jined that ne\] brake shoes Here required and the nec.han.Lc i)roc:,'eded to vacuUlU the brake druca and replace the shoes. He did not ,,,rear a respirator as a need was not apparent. Time involved 24 minutes as s2mpl:Lng time. AsbeEtos t:iber count Has 0.4 fi.bers per mL of air ,,,ith the threshold limi.t valve (ILl:') being two :Eibers greater than five EliCrOiIleters In length. _~ECOND: The left rear wheel Vlas removed for inspection and the need for replacement Has apparent. At our request, the mechanic Vlore a 3~'1 respirator 3:1.d Ubed compressed air to clean the brake d-ru8 before changing the brake shoes. Si.grtificant quantities of fine dust va::; generated, ,o,rhic.h dispersed throughout the shop. Zlapsed time and/or sar;;pling time was 19.5 minutes. Asbestos fiber count of fibers greater than five micrometers in length was 0.2 per ml of air. There. ,ol3S cODsiciel:'.'lble dust collected on the sample Dut less fibers, possibly due to air dispersion. THIRD: The right front disc brake was removed, inspected, and replaced during a sampling time of t,.JO minutes. No air or vacuum Has used. The results ''ere L 9 fibers per ml, ~olhich l:i.kely indicates the greatest exposl,re potential associated \li_th routine brake service to be the removal and replac.ement: of the u;1E'el for inspection when additional work is Hot required. This factor is time related. vie are of the opinion that even at the ne\~ two~fiber TLV~ there is generally no problem Hith excessive exposure to asbestos in the automotivQ garag(~. Use of the recently ac.quirC"d vacuum capability should continue to b2 required. The 3H respirators should be used on any special oc.casiou where dust levels are suspect oE being excessive. t-~r_ Hofflnart should be. informed of the results of thes~ measurements, and if there are questions, please call me at 6161. /..jll P 4. : '_ ..,,' ~ , .' . Mr. J. F. Ballew, Jr. Building 70-l08A INSTITUTE PIAVf Ms. B. J. }1itchell Hr. J. G. Perkins Mr. F. Wil1iams Apr i l (}. 1976 E.R. - Industrial Hygiene You have asked that measurements be made of personnel exposure to airborne asbestos fibers vhile ,,'eighing dishes are being prepared for residue analyses. Our records show that a similar measurement was made in Specifications Laboratory Room 205, ~[arch 10,1975, and was reported to be slightly above threshold limit value (TLV). Three determinations have recently been made by fiber count on filter samplers worn by employees while preparing sample dishes in the Analytical Laboratory Room 108. Tbe results of these samplings are as follows: ''---'" Date Em~)loyee 1"iber Count/ml Air 12(22/75 1/12/76 3/1/76 C. \.I.'. Devers D. DeLuca J. O. Good 4.9 47.6 7.7 We observed each of these samplings to be similar in technique and airborne dust was not visible in either instance. The TLV for aSDestos dust exposure is currently 5 fibers greater than 5 micrometers in length per cc of air as a time weighted average (TWA) and a ceiling value not to exceed 10 fibers greater than 5 micrometers in length. As of July I, 1976, the TLV will be reduced to 2 f ioer s as an OStIA. allowable limit. This job task is only infrequently performed and it is unlikely that the TLV as TWA would ever be exceeded. Our measurements, however, show that the ceiling level can be excessive. He, therefore, recommend that 'Work involving preparation of sample dishes with asbestos fibers be performed within an exhaust ventilated hood. HIlt" :ls '7/ ;, 1'\/(l;;i/ ,_".~/ e" / /~~ ,)-t:..-t v H. H. Frazie// UCC 008858