The known hazards of nickel carbonyl are reviewed and recommendations are made for control measures in occupational environments. Human effects resulting from accidental exposure to nickel carbonyl include pulmonary edema, interstitial pneumonitis, reduced lung capacity, heart disorders, liver enlargement, and in severe exposure cases, death. In animal carcinogenicity studies, rats developed lung tumors from both long term and acute exposure to nickel carbonyl vapor. Human epidemiologic data are insufficient to either confirm or deny a causal relationship between the increased incidence of lung and nasal cancers and nickel carbonyl exposure in nickel refinery workers. The 1 part per billion nickel carbonyl standard should protect workers from any carcinogenic and other adverse health effects associated with nickel carbonyl exposure. Methods for detecting nickel carbonyl in the air are described.