What are pollutants?
Pollutants can be classified into 2 different categories
- Primary: directly emitted from a process
o Ash from a volcanic eruption
o Carbon Monoxide gas from a motor vehicle exhaust
o Sulphur Dioxide released from factories
o Examples are particulates, carbon monoxide, nitrogen oxide, and sulfur oxide.
- Secondary: not emitted directly but instead, formed in the air when primary pollutants react or interact
o Ground level ozone, which is formed when hydrocarbons (HC) and nitrogen oxides (NOx) combine in the presence of sunlight
o NO2, which is formed as NO combines with oxygen in the air
o Acid rain, which is formed when sulfur dioxide or nitrogen oxides react with water
o Ozone and secondary organic aerosol (haze)
References
http://www.greenfacts.org/glossary/pqrs/primary-pollutant-secondary-pollutant.htm http://pollution.ucr.edu/primaryvssecodarypollutants.html