Glossary
The following definitions are provided to clarify words or phrases used on this website.
Ambient Air: All space outside of buildings, stacks or exterior ducts.
Area Source: These are small stationary and non-transportation-related sources that do not emit very much pollution by themselves, but collectively, they contribute significantly to air pollution.
Attainment Area: A geographic area that is in compliance with all of the National Ambient Air Quality Standards (NAAQS).
Criteria Pollutant: Pollutants for which EPA has set National Ambient Air Quality Standards (NAAQS). These include Ground-level ozone, PM10, PM2.5, carbon monoxide, sulfur oxides, nitrogen dioxide, and lead.
Emission: The release or discharge, directly or indirectly, into the air of a one or more air pollutants.
Fugitive Emissions: Emissions that are released from sources other than a stack, chimney, pipe, vent or other discharge opening. An example would be a leak or evaporation of solvents while cleaning.
Non-Attainment Area: A geographic area that does not meet one or more of the National Ambient Air Quality Standards (NAAQS).
Non-Point Source: A source that does not have a single point or origin.
Point Source: A source that has a fixed (defined) emission point such as a smoke stack.