Document Xz8YJa1DO5xwkaXqNn4RDKyr4

October 1, 1969 Dated August 13# 19^9 Attached plus* find eopy of tbs subject report. Both solss and toxle dust exposures r investigated. As jou vill note, there are problems In both anasa. BOOT I bam corrected tbs threshold Limit Yaluee (TLV) shoea an the attached Air Analysis Sable because the Thine for asbestos baa lowered from 5.0 to 2.0 Killian fertlclas per Cubic foot tappet.). this lowering vill also affect the 10.0 SET for BpreyDon, hut Z an not sure exactly how naeh. Cdly Bureau of Mines improved reepiretora should be von by all operators and those others that are eaqpoeed to asbestos or SprayDan dusts. Respirators should ha periodically hyglantcally cleaned, preferzehly dally. There Is soon question Just how each further yon can reduce the dust exposure, feptylng of bags and handling of eapty bags, etc., offer serious exposure. At this tins, bulk handling la not feasible. However, excellent housekeeping shmld be maintained and all dust collection equipment should be kept at . cgtigum efficiency. XOISH As we vert all aware, the Cupola area offers the only real eaposure. In the U. 8., the federal gawirmant states that persona can ha exposed to 90 decibels for eight hours an the A Scale without bam belxgt incurred to about 65 percent of the population. Anything above that nay cause damage or ts^oraiy threshold shift. .. Ve are only Interested in tbs A Beale valnaa. The C Scale us there is noise in the high frequency areas if C Seale readings are higher A Beale readings, fills can he helpful in designing acoustical absorbers, ate. feraannul exposed to excessive noise levels should be provided with the best ear plugs ccnmercially available. Also, an acoustical typo enclosure should be considered. Xven if it Isn't totally enclosed, there could be a eajor noise redaction. After yon have opportunity to review the attached report and this ono, I would appreciate hearing from you. CS024 0461