Document 3JNyGv689Qga66jovm3zE1pwO

4 lr** * J/'l SHELL OIL COMPANY IOMA RTINl-ZZ MA NU FACTU RING COMPLEX - CAFETY UEPARTMEN! MANAGER Vr'ILM INC TON/ DOM INC UE7 MANUFACTURING COMPLEX SAFETY DEPARTMENT - MANAGER tul! UINE ?.0,' 197 5 Iui,MlNnU.':TRIA L HYGIENIST "department of occupation/ ' AFETY AND HEALTH WALNUT CREEK" M'fmaEVALUATION - EMPLOYEE SAFETY AND ABRASIVE B LASTING During separate plant visits Messrs Pickens, Wilmington/ Dominguez Manufacturing Complex, and Dodd, Martinez Manufacturing Complex, asked the question, "Wh.it ia tha silica exposure to Shell emr>lnyre working downwind of an abrasive blasting operation? " To answer the question, air samples were collected at Martinez Manufacturing Complex during a test designed to compare the cleaning efficiency and airborne levels of two abrasives: sand; and Kleen Blast, a commercial crystalline copper slag material containing oxides of silicone, iron, aluminum, calcium, magnesium, copper, and manganese. The manufacturer of Kleen Blast claims It contains no free silica and is safer than and still as effective ao sand. On March 31, April 1 and April 9, 1975, air samples were collected during the abrasive blasting of a storage tank exterior at Martinez. Manufacturing Complex. The results of the air sampling are contained in Figure l and the attached table. While the employees doing the work wo re respiratory protection, the data represents air onccntratione for unprotected workers since other employees working in the area would not routinely wear re epi rato r s. The results show that: The major air contaminant from sandblasting is free silica while CaO and inert dust arc major contaminants from the Kleen Blast operation. There is no free silica hazard from Kleen I31ast. o At the point of blasting the current Federal OS HA standard for respirable free silica of 0. A mg./M^ is exceeded by a factor of up to S. 0 for rand. With Kleen Blast the 10 rng/.vM proposed Cal-OSH standard tor total inert dust is exceeded by a factor oi up to 5. :i. Neither the standards for CaO or re so: .'able inert dust were u:n.ceded for Kleen Blast. LAM 005161 DPMC-02770 EVALUATION - EMPLOYEE 'A !' f-'.TY AND ABRASIVE BLASTING 2 Approximately 50 feet downwind of the blasting, the level of contaminants from Klcen Blast arc below the applicable O.SHA standards, while for sand the 0.7 mg/W^ calculated total silica proposed Cal-OSH standard is exceeded by a factor of up to 2.2. o Approximately 12 5 foet downwind of the sandblasting, the airborne silica level was still 35% of the 0. 3 mg/M^ t alculated respirable silica dust OEM A standard. In conclusion, this study helps to answer the above question. It indicates that there is a silica exposure to employees working up to 125 feet downwind of a sandblasting operation. "While such, exposures are subject to varying weather conditions, such as wind velocity and direction, had employees been working 125 feet downwind of this sandblasting situation, their exposure to free silica would hava approached 35% of the current OcHA respirable silica standard. However, if the proposed NIOSH level of 0.05 mg/M^ for silica is adopted, employees 125 feet downwind of a sandblasting operation would be working in an area considered a "free silica'" work area and hence be subject to the requirements of the standard, l. e. monitoring, recordkeeping, respirator program, and medical examinations. The Industrial Hygiene Sampling Forms for these samples were forwarded to Jerry Hcrmen* at Martinez, for the plant files. If there are any additional questions, please advise. Ofb;hfii ! ~'/ S. L KllUALY, j;i :. L. Killlany, Tr." Attar hme nts cr (w/a): Head Office - Manufacturing - Safety Health - Manager Head Office - Dept, of Occu. Safety & Health - Staff Ind. Hyg. Head Office - Public Affairs - Medical Director Wood River - Regional Industrial Hygienist New Orleans - Regional Industrial Hygienist Houston - Industrial Hygiene Lab Coordinator lam 005162 DPMC-02771 w ri\iuhi', . ^ qN NWIND RESPIRRSLE 5IL.ICR LEVELS " */ . DURING 5HNDBLR5TING F C R L/D 5H p M jPDSCD L IM IT LAM 005164 DPMC-02773