of their extreme toxicity, ability to disperse and quantity. Each substance
shall be assigned a Substance Hazard Index (SHI) number to rank the risk
associated with the substance. Substances with an SHI greater than or equal to
8,000 shall be regulated.
The SHI is derived as follows:
SHI = EVC
ATC
Where:
ATC is the acute toxicity concentration in parts per million defined as the lowest reported concentration, based on recognized scientific protocols, that will cause death or permanent disability to humans from an exposure duration of 1 hour. Extrapolations from various sources of data are permitted using scientifically recognized methods. If toxicity data based on recognized scientific protocols are unavailable, the EHS ATC is set at 10.0 parts per million.
Where:
EVC is the equilibrium vapor concentration at 20/dC. defined as the substance vapor pressure at 20/dC. in millimeters of mercury multiplied by 1,000,000 divided by 760. For powders, solids or aerosols, the substance vapor pressure is replaced by the maximum substance concentration that can be conveyed in air after a settling distance of 100 meters from the point of emission.
When the actual quantity of an EHS is less than the TQ or when any other hazardous substance is present at a facility, then responsible person(s) must comply with the general duty statement pursuant to § 7704(a) of this title.
7 Del. C. § 7707