OSHA PELs, NIOSH RELs, IDLH values, and the meaning of TWA, STEL, ceiling ('C') limits, and the Skin notation; how exposure limits are derived, computed (mixtures, extended shifts), and applied through the hierarchy of controls. Emphasis on interpreting and applying limits and notations — not memorizing specific values from Tables Z-1/Z-2/Z-3.
An employee works an 8-hour shift in a lead-processing facility. For 4 hours, they are in an area with 200 µg/m³ of airborne lead while wearing a respirator with a protection factor of 10. For the remaining 4 hours, they are in an area with 0 µg/m³ of lead and no respirator. For the purpose of determining compliance with the PEL, what is the employee's calculated 8-hour TWA?