Airborne Exposure Limits: Alumina (Aluminum Oxide): -OSHA Permissible Exposure Limit (PEL): alpha alumina, 15 mg/m3 total dust, 5 mg/m3 respirable fraction -ACGIH Threshold Limit Value (TLV): aluminum oxide, 10 mg/m3 (TWA) inhalable (total) particulate matter containing no asbestos and < 1% crystalline silica, A4