A general term used to describe the quality of the outside air. Usually adjectives
such as good, fair, bad, etc. are used by the media to describe this; often some form
of
air pollution or air quality index is employed to determine the specific descriptive term to be
used. These are very qualitative terms of little or no scientific value.
Source:
PAC, 1990, 62, 2167
(Glossary of atmospheric chemistry terms (Recommendations 1990))
on page 2173