Which chemicals are covered by the general duty provisions?

For CAA section 112(r)(1), General Duty, what are the chemicals that are covered?

There is no specific list of substances which subject a stationary source owner or operator to the general duty provisions. The general duty provisions apply to owners and operators of all stationary sources which have any "extremely hazardous substances". Extremely hazardous substances are not limited to the list of regulated substances listed under section 112(r), nor the extremely hazardous substances under EPCRA §302 (40 CFR Part 355, Appendices A and B).

Although there is no definition for extremely hazardous, the Senate Report on the Clean Air Act provides criteria EPA may use to determine if a substance is extremely hazardous. The report expressed the intent that the term "extremely hazardous substance" would include any agent "which may or may not be listed or otherwise identified by any Government agency which may as the result of short-term exposures associated with releases to the air cause death, injury or property damage due to its toxicity, reactivity, flammability, volatility, or corrosivity" (Senate Committee on Environment and Public Works, Clean Air Act Amendments of 1989, Senate Report No. 228, 101st Congress, 1st Session 211 (1989) - "Senate Report").

As the Senate makes clear, "the release of any substance which causes death or serious injury because of its acute toxic effect or as a result of an explosion or fire or which causes substantial property damage by blast, fire, corrosion or other reaction would create a presumption that such substance is extremely hazardous." Senate Report at 211. Revisions to the list of regulated substances under CAA 112(r) do not affect the applicability of the general duty provisions.