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 industrial employee is monitored for exposure to a vapor with an 8-hour permissible exposure limit of 100 ppm. Personal sampling results indicate the following exposures: 150 ppm for 2 hours, 75 ppm for 2 hours, and 50 ppm for 4 hours. What is the calculated 8-hour time-weighted average (TWA) for this shift?