General Glossary

A cancer IHB is a concentration in ambient air, at or below
which a chemical or defined mixture of chemicals is unlikely to
cause an adverse health effect to the general public when
exposure occurs daily throughout a person's lifetime. Cancer
IHBs are based on unit risk values and the judgment that 1
additional chance in 100,000 of getting cancer in a lifetime is
acceptable. For implementation purposes, cancer IHBs are
typically compared to an annual average concentration of a
chemical or defined mixture of chemicals in air.

A chronic noncancer IHB is a concentration in ambient air, at
or below which a chemical or defined mixture of chemicals is
unlikely to cause an adverse health effect to the general
public when exposure occurs daily throughout a person's
lifetime. Noncancer IHBs are used for effects other than
cancer. For implementation purposes, chronic IHBs are
typically compared to an annual average concentration of a
chemical or defined mixture of chemicals in air.

Also known as: Propylene. CAS Number: 115-07-1. A flammable,
gaseous hydrocarbon obtained by cracking petroleum hydrocarbons.
It is used chiefly in organic synthesis. Chemical formula =
C3H6. Molecular weight = 42.08 g/mol.

To take up or receive by chemical
or molecular action.

A material with pH of less than 7.0

Removing contaminants from water
by enlarging the water's surface
area and forcing air over it to
evaporate volatile contaminants

Federal and state government-
prescribed levels of a pollutant
in the outside air that cannot be
exceeded during a specified period
of time in a specified
geographical area.

Simple rootless plants that grow
in bodies of water in relative
proportion to the amount of
nutrients available.

An unusual, sudden or excessive
abundance of algae. Algal blooms
can adversely affect water quality.

Capacity of a lake to neutralize
acid.