Document ym0wnpL6qyGKjjNVe7o4Z7gD

f;' >r, fU`l"f v ) Va: SHELL OIL COMPANY date February is, 1975 PLAINTIFF'S EXHIBIT 70 HEAD'office - MANUFACTURING SAFETY AND HEALTH - MANAGER mom REFINERY SUPERINTENDENT MARTINEZ MANUFACTURING COMPLEX suB-Ecr EMPLOYEE EXPOSURE TO FREE SILICA Please refer to your letter of January 9, 1975, advising us of the overexposure of sandblasters to free silica wearing air-supplied respirators and recommending that we evaluate our sandblasting operations with air sampling. In all confined blasting, our personnel are required to wear a pressure demand air line respirator. They wear single-use dust respirators and canvas protec tive hoods in open-air blasting. We concur that air sampling should be done for the blaster with the dust respirator and for personnel in the vicinity in both situations. The California Air Resources Board has adopted a strict air contamina tion regulation on abrasive blasting (air contaminant limited to Ringlemann No. 2). We are in the process of evaluating an obsidian blasting abrasive, "Kleen Blast," which will eliminate exposure to free silica and aid in complying with the air contamination regulation. In the event Kleen Blast proves to be an acceptable abrasive for our blasting requirements, air sampling for free silica will not be required. We would, however, continue to monitor our blasting operations for nuisance dust. R. Lopez cc - Regional Industrial Hygenist (H. McDermott), Shell Chemical Company, 1500 Newell Avenue, Walnut Creek, California 94596 Regional Representative - Environmental and Safety Affairs (J. D. Joyce), Shell Oil Company, San Francisco, California LAM 0315667.061 i / ABS-003289