In 1990, the U. S. Congress responded to catastrophic accidents221 in chemical facilities and refineries by including in amendments to the Clean Air Act a requirement that OSHA and EPA publish new regulations to prevent such accidents. The new regulations addressed prevention of low-frequency, high-consequence accidents. OSHA’s regulation, “Process Safety Management of Highly Hazardous Chemicals,”(29 CFR 1910.119) (PSM standard) became effective in May 1992. This standard contains broad requirements to implement management systems, identify and control hazards, and prevent “catastrophic releases of highly hazardous chemicals.”