Document REdd4d6jmyp38QbND5L6o55k

PLAINTIFF'S EXHIBIT SM-32-MC {OEV 4-TV) Shell Oil Company Shell Chemical Company Interoffice Memorandum FEBRUARY 10, 1987 ATrACHme*r I FROM: INDUSTRIAL HYGIENIST - HS&E - WMC TO: SENIOR INDUSTRIAL HYGIENIST - MPG. 6, TECHNICAL HEALTH & SAFETY - H.O. SUBJECT: 12-HOUR SHIFT EXPOSURE As a follcw-up to our previous discussions, Wilmington Manufacturing Conplex requests Head Office's assistance in determining the criteria applicable, when corparing Permissible Exposure Limits (PEL's) of chemical substances (based upon an 8-hour shift), as compared to that of a 12-hour shift. We recognize that PEL'S are established based upon 8-hour work shifts. Now that operators at WC are working 12-hour shifts, we are trying to determine hew the 8-hour PEL's can be applied. Of particular concern at this time are: Benzene Soluble Fraction, Coke Dust, Benzene, Toluene, Xylene and HaS and SOa. We are also looking for an applicable P.E.L. for the other chenicals of which we routinely sample. Guidance on this issue is needed to respond. Thanks in advance for your cooperation in this matter. S. V. Sever SVS:pes cc: RAT/MSB/IH File BEP8704101 ABS-046715 ft a ocHm<fN r 2 OSHA Instruction CPL 2-2.20A V-ird J 0 WC'-t Office of Health Compliance Assistance 2. Non-traditional Work Schedules. The 8-hour exposure limits for some substances may not provide appropriate protection from health hazards when non-traditional work schedules are utilized, e.g., exposure longer than 8-hours/day, four 10hour days/week, six 7-hour days/week, etc. a. In general, single or multiple samples should be taken to determine any 8 hours of exposure for comparison with the PEL. A separate sample should be used to determine any additional exposure beyond the 8 hours. b. Additional instructions on sampling and evaluation of sampling data shall, in such cases, be sought from the Assistant Regional Administrator (ARA) for Technical Support, who shall in turn contact the Directorate of Technical Support. D. Unsampled Work Periods. 1. Estimated Exposure. Professional judgment is necessary for making any conclusions or assumptions regarding unsampled work periods. a. For example, if the workshift is 8 hours, and sampling was conducted for 7 hours and 15 minutes, the CSHO needs to make some professional judgment regarding the unsampled 45-minute period. b. A zero exposure shall be assumed unless the CSHO can support a professional judgment on the magnitude of the exposure for the unsampled period. Thus, a TWA should generally be calculated by dividing the sample results by 8 hours rather than the actual time sampled. 2. Rationale for Judgment. Given sufficient information, a professional judgment on estimated exposure for the unsampled period can be supported. The rationale for this judgment must be carefully documented, however. a. For example, if an 8-hour operation is continuous and the concentration of the substance would not be likely to vary substantially due to the process; and if the employee by virtue of the job could be assumed to.be exposed continuously to essentially the same concentration, it would then be acceptable to assume that the exposure for the unsampled time would be the IV-2 ABS-046716  1910.1025 29 CFR Ch. XVII (7-1-85 Edition) M3 FR 196 24. May 5. 1918: 43 FR 28472. June 30. 1978. as amended at 45 FR 35262. May 23. 19801 jj 1910.1025 Lead. (a) Scope and application. (1) This section applies to all occupational ex posure to lead, except as provided in paragraph tax2). (2) This section does not apply to the construction industry or to agri cultural operations covered by 29 CFR Part 1928. (b) Definitions. "Action level" means employee exposure, without regard to the use of respirators, to an airborne concentration of lead of 30 micrograms per cubic meter of air (30 fig/ m') averaged over an 8-hour period. "Assistant Secretary" means the As sistant Secretary of labor for Occupa tional Safety and Health, U.S. Depart ment of Labor, or designee. "Director" means the Director. Na tional Institute for Occupational Safety and Health (NIOSH). U.S. De partment of Health. Education, and Welfare, or designee. "Lead" means metallic lead, all inor ganic lead compounds, and organic lead soaps. Excluded from this defini tion are all other organic lead com pounds. (c) Permissible exposure limit (PELX. (1) The employer shall assure that no employee is exposed to lead at concen trations greater thru) fifty micrograms per cubic meter of air (50 pg/ra1) aver aged over an 8-hour period. (2) If an employee is exposed to lead for more than 8 hours in any work day, the permissible exposure limit, as a time weighted average (TWA) for that day. shall be reduced according to the following formula; Maximum permissible limit (In pc/ mb-400-r hours worked In the day. (3) When respirators are used to sup plement engineering and work practice controls to comply with the PEL and all the requirements of paragraph (f> have been met, employee exposure, for the purpose of determining whether the employer has complied with the PEL, may be considered to be at the level provided by the protection factor of the respirator for those periods the respirator is worn. Those periods may be averaged with exposure levels during periods when respirators are not worn to determine the employees daily TWA exposure. (d) Exposure monitoring--(l) Gener al. (I) For the purposes of paragraph (d(. employee exposure is (hat expo sure which would occur if the employ ee were not using a respirator. (ii) With the exception of monitor ing under paragraph (d)(3), the em ployer shall collect full shift (for at least 7 continuous hours) personal samples including at least one sample for each shift for each job classifica tion in each work area. (iii) Full shift personal samples shall be representalive of the monitored employee's regular, daily exposure to lead. - (2) Initial determination. Each em ployer who has a workplace or work operation covered by this standard shall determine if any exployee may be exposed to lead at or above the action level. (3) Basis of initial determination, (i) The employer shall monitor employee exposures and shall base initial deter minations on the employee exposure monitoring results and any of the fol lowing, relevant considerations; (A) Any information, observations, or calculations which would indicate employee exposure to lead: (B) Any previous measurements of airborne lead; and (Cl Any employee complaints of symptoms which may be attributable to exposure to lead. (il) Monitoring for the initial deter mination may be limited to a repre sentative sample of the exposed em ployees who the employer reasonably believes are exposed to the greatest airborne concentrations of lead in the workplace. ' (iii) Measurements of airborne lead made in the preceding 12 months may be used to satisfy the requirement to monitor under paragraph (d)(3)(i) if the sampling and analytical methods used meet the accuracy and confi dence levels of paragraph (d)(9) of this section. (4) Positive initial determination and initial monitoring, (i) Where a determination conducted under para graphs (d) (2) and (3) of this section shows the possibility of any employee 746 BEST AVAIU&t COPY $ Occupationol Safety and Health % X exposure at or above the action the employer shall conduct m< i ing which is representative of t posure for each employee in the f place who is exposed to lead. * (il) Measurements of alrborn made in the preceding 12 montt be used to satisfy this requiren *. the sampling and analytical m \ used meet the accuracy and dence levels of paragraph (d)(9) section. (5) Negative initial detcrmii Where a determination, con under paragraphs (d> (2) and this section Is made that no err is exposed to airborne concent of lead at or above the actioi the employer shall make a record of such determlnattoi record shall Include at least th> matton specified In paragraph ( this section and shall also inch date of determination, location the worksite, and the name ansecurity number of each en monitored. (6) Frequency. (1) If the initte toring reveals employee exposu a below the action level the rr men Is need not be repealed e> t otherwise provided in paragrap Cf C, of this section. (it) If the initial determlns subsequent monitoring revei ployee exposure to be at or at action level but below the per exposure limit the employ* repeat monitoring in accordar this paragraph at least < months. The employer shall t monitoring at the required fr until at least two consecutive i ments, taken at least 7 days ai below the action level at wh 4': tJ, T the employer may discontint toring for that employee e: otherwise provided in paragr&i of this section. (ill) If the initial monltorin that employee exposure Is a' permissible exposure limit thr er shall repeat monitoring q The employer shall continue ing at the required frequenej least two consecutive meast taken at least 7 days apart. ( the PEL but at or above tl level at which time the emplc i ABS-046717