Document B5mma4gMDZZ62LpXqx1DGv8gE

miMiUATU set tout ov i'uhuc ur.Ai.m univiiisiiy or nrisiiUKon WrVMlUHliM. Pl.NNSYI VANIA IS2I3 tHTAHIMt.Nr or OCCUPATIONAL HEALTH December 16, 1968 Hr* E, 8. Waters, Jr Research Supervisor Armstrong Cork Company Research and Development Center Lancaster, Pennsylvania 1760h Dear Mr* Waters: The airborne dust samples wore, as you noted, quite heavy. The dust deposit on the membrano fitter was so thick, that the deposit came off during the transport. For this reason we had to resuspend the collected dust in water with a wetting agent and refiltcr 1/10 of this suspension onto new membrane filters. The results in the enclosed table are therefore not quite as accurate as by the direct technique. ' From the hygienic standpoint the airborne concentrations are also too high. The Threshold Limit Value for Asbestos dust is 5 MPPCF, The basis for this number is still the old impinger technique with 10x bright field objective and lOx eyepiece. With this old technique fibers thinner than approximately 1 |t were cither not collected or not visible. The phase contrast method evaluates fibers down to a thickness of Q.3vi so that the particle and fiber count will be higher with the new more sensitive method. I understand that these samples were only of exploratory nature taken at the point of spraying and not in the direct breathing zone of the operator and I am sure we wi 11 cosily arrive at the right sampling time and flow rate for the dust samples. Please let me know if you have any questions. Very truly yours, FS/cp enclosure Felix Stein Research Associate *yi cL^.c, "g<?7 ^ l i HPPCF - HJi>n> <i f 1968 SAMPLES SU:-iXAR!t OF P A R TIC LE A13D F IB E R COUHT w M U nl E p0i) rJ 8 * rJ v> < V-1 uo !0 41 +i > fn v Wo fr- Vci *o ts K t, o* fj <i s! *-1 S c- rv/ Xio S *1 0 su 0 -y n v> fJ o H-j > M $ Ck Si) o ro is * >1 V, 5* W tn N < vl fs r4 O O' > N1 r A fsl 0 K) r> ~N. WM >M S l i M1 N. 'U 01 QJ ti nn 3a O trt* (u w *) C* S % v> M C\ o <r0o O' 0** N Vi FOR r->o <u_ Ji 1 <0 v/> o O rO (N OJ 11 *-n o ; i: t\j M \SM ' da graduate school of public health UNIVERSITY OF PITTSBURGH m'lSIlUIKai. PENNSYLVANIA 15213 I >11'AKIMliN I <H OCCUPATIONAL III.ALI il February 11, 1969 Mr. F. B. Waters, Jr. Ilosoarch Supervisor Arms Irons Cork Co. Lancaster. Pa. 17601 Dear Mr. Waters: The six samples of airborne dust shipped to us on January 30 wm-o analyzed for Particle and Fiber count. The particle count in our reports doe3 not include the fiber count. Results: Sample Air Volume Particles Fibers MFPCF - eff MPPCF 5p 5-1 Op 10p 1 0.20 340 29 27.3 + 8.2 none 12.4 + 5.5 o c 2 81.8 13.8 74.4 9.6 21.1 4 5.1 34.7 6.6 3 0.20 323 28 231 24 19.8 7.0 39.6 9.9 1 0.20 340 29 421 + 32 42.4 4 10.2 49.6 + 11.1 5 0.20 372 4 30 159 + 20 32.2 + 8.9 44.6 10.5 6 0.15 85.7 + 5.0 1.77 + 0.72 1. 47 + 0.66 1.18 0.59 MPPCF " Millions Particles per cubic foot of air. MFPCF - Millions Fibers per cubic foot of air In your letter from January 28, 1069, you mentioned that the samples were taken near the point of spraying. This method is correct if you are interested in technical data for your spray nn/./.lo. From the hygienic standpoint, on the other hand, whore you are interested in the exposure to the workers, it is necessary to sample near the breathing zone of the operator. The concen tration of dust and fibers near the mouth and nose of the worker is always much lower than at the source. Proper ventillation (local exhaust, hood, or general dilution ventillation) will re duce the exposure further or may even eliminate it totally. i don't know t lie objectives oi your sampling and your probl(ins but we will be glad to assist you and answer any Tur t her ques tions. Very truly your s, Felix Stein i FS/lsk