Classification of Air Pollutants

Classification of Air Pollutants

Air pollutants are classified as

I. Natural pollutants

II. Anthropogenic pollutants

III. primary pollutants

IV. Secondary pollutants

1) Natural pollutants

Natural pollutants are those that are found in nature or are emitted from natural sources.

For example, volcanic activity produces sulfur dioxide, and particulate pollution may derive from forest fires or windblown dust.

2) Anthropogenic pollutants

Anthropogenic pollutants are those that are produced by humans or controlled processes. For example, sulfur dioxide is produced by fossil fuel combustion and particulate matter comes from diesel engines.

3) Primary pollutants

Primary pollutants are those that are emitted directly into the atmosphere from an identifiable source. Examples include carbon monoxide and sulfur dioxide.

4) Secondary pollutants

Secondary pollutants are those that are produced in the atmosphere by chemical and physical processes from primary pollutants and natural constituents.

For example, ozone is produced by hydrocarbons and oxides of nitrogen (both of which may be produced by car emissions) and sunlight