An emission control system that reduces NOx emissions through the catalytic reduction of NOx in diesel exhaust to N2 and H2O by injecting nitrogen-containing compounds into the exhaust stream, such as ammonia or urea
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}