Document bajdovpo1EQgEvV0e3K4Jg5L3

Claylon Environmental Consultants, Inc. - 3- Safety Appliances Company, Model C). Breathing zone samples were obtained by fa toning the pump to the operator's belt and the fii -.-r head to the outside of his collar at approximate b.tathing zone height. Thus, the breathing zone scmple was representative of the time-weighted average conditions to which the operator was exposed during the sampling period. Each sample was analyzed subsequently for asbestos fibers using the method specified by the National Institute for Occupational Scfety and Health. Briefly, fchis .method consists of the following steps: a pie-shaped section of each filter is cut carefully from the filter and mounted on a standard microscope slide using a high vis cosity solution of membrane filter material in a 1:1 mix ture of diethyl oxylate and dimethyl phthalatc to render the filter transparent. Asbestos fibers, defined as particles having an aspect ratio (apparent length to width) of three or greater, which were observable on thi surface of the filter were counted using a 10X eyepiece and a 40X objective with phase contrast i 1 lu'`:J.natior., A minimum of 100 fields, selected at random on the sam ple, were examined and fibers greater than five micro meters in length were counted. The microscopic analy sis, that is, fiber count data, was used in conjunction with field sampling data (air flowrates and duration oi sampling) to calculate the concentrations of asbestos fibers in air corresponding to each sample in units of fibers, greater than five micrometers in length, per cubic centimeter oi air. This procedure is consistent with the nethdd used by the Occupational Safety and Health Administration in its com pliance effort. Data thus obtained were then compared to applicable standards promulgated by the Occupational Safety and Health Administration (OSHA) and by the Ameri can Conference of Governmental Industrial Hygienists (ACC1H). The present OSHA and ACG1H standards limit eight-hour, time-weigh ted average exposures of workers to a concentration of five fibers (greater than five micromaters in length) per cubic centimeter of air. Effective July 1 , 19 70 , the OSHA limit for eight-hour, time-vcighted average exposures is scheduled to be re duced to two fibers per cubic centimeter of air. The present OSHA standard also establishes a ceiling (or peak.) exposure limit of ten fibers per cubic centimeter of air. O.i October 9 , 1 975, OSHA issued proposed rulemaking tu jo. er the priM iit standard* such, tbst eighthour, t i r.ei i e :! overage exposures would be 1 i r.. j. t e d to -.3 fibir y.r cubic centimeter of air, and ctiiii.g exposures mcasuriJ over a period up to fifteen minutes would be limited to five asbestos fibers per cubic centi me: ir , of r.Jr. V'h- proposed standard is harsd 1 s r 1 y on PRODUCED BY FORD