40 C.F.R. § 1604.2
As used in this part, the following definitions apply:
Accidental release means an unanticipated emission of a regulated substance or other extremely hazardous substance into the ambient air from a stationary source.
Ambient air means any portion of the atmosphere inside or outside a stationary source.
Extremely hazardous substance means any substance which may cause death, serious injury, or substantial property damage, including but not limited to, any "regulated substance" at or below any threshold quantity set by the Environmental Protection Agency (EPA) Administrator under 42 U.S.C. 7412(r)(5) .
General public means any person except for:
Inpatient hospitalization means a formal admission to the inpatient service of a hospital or clinic for care.
Owner or operator means any person or entity who owns, leases, operates, controls, or supervises a stationary source.
Property damage means damage to or the destruction of tangible public or private property, including loss of use of that property.
Regulated substance means any substance listed pursuant to the authority of 42 U.S.C. 7412(r)(3) .
Serious injury means any injury or illness that results in death or inpatient hospitalization.
Stationary source means any buildings, structures, equipment, installations, or substance-emitting stationary activities which belong to the same industrial group, which are located on one or more contiguous properties, which are under the control of the same person (or persons under common control), and from which an accidental release may occur.
Substantial property damage means estimated property damage at or outside the stationary source equal to or greater than $1,000,000.
40 C.F.R. §1604.2