A term referring to chemical reactions brought about by the light energy of the sun. The reaction of nitrogen oxides with hydrocarbons in the presence of sunlight to form ozone is an example of a photochemical reaction
California Air Resources Board ARB (California Environmental Protection Agency), glossary of air pollution terms, Sacramento, CA, USA 2013. http://www.arb.ca.gov/html/gloss.htm, (Air Pollut - Amer) {594}