HETA 88-031-1894 NIOSH INVESTIGATOR:

findings of high blood lead levels (in excess of 50 micrograms per deciliter) among two employees who worked in the mine's fire assay laboratory. Since that time, the company had installed local exhaust ventilation and increased emphasis on respiratory protection, and was interested in determining means of further reducing employee exposures. In December 1987, the NIOSH investigator conducted an environmental survey. During this survey, personal and area air samples were collected in the fire assay laboratory to determine concentrations of airborne lead and other trace metals. Air velocity measurements of the local exhaust ventilation systems in these areas also were made. The results of the environmental survey revealed 8-hour TWA concentrations of 113 micrograms per cubic meter of air (ug/M3) and 40 ug/M3 of lead in the personal air samples collected for the assayer and scale operator, respectively. While both of these concentrations are below the Mine Safety and Health Administration (MSHA) standard of 150 ug/M3 as an 8-hour TWA, the concentration found in the assayer's breathing zone was above the Occupational Safety and Health Administrations (OSHA) Permissible Exposure Limit (PEL) of 50 ug/M3 as an 8-hour TWA. In addition, the concentration in the breathing zone of the scale operator was above the OSHA action level of 30 ug/M3 as an 8-hour TWA. It should be noted that both of the employees were wearing respiratory protection at all times when in the furnace and storage rooms. Provided their respirators were properly fitted and maintained, their actual exposures would be expected to be lower than the measured values. Area air samples collected in each of the rooms comprisin