Use a NIOSH/MSHA or European Standard EN 149 approved respirator if exposure limits are exceeded or if irritation or other symptoms are experienced...http://www.chemcas.org/drug/analytical/cas/129-00-0.asp MSDS Benzo[a]pyrene, 98% CAS 50-32-8 MSDS 3,4-Benzopyrene; 3,4-Benzpyrene; Benzo[def]chrysene. .