nitrogen oxides

The abbreviated form by which nitrogen oxides are known. This group of gases includes both nitric oxide (NO) and nitrogen dioxide (NO₂) and those resulting from the combination of both and also with oxygen. The NO₂ is a secondary pollutant generated in high-temperature combustion, due to the oxidation of NO. It is a highly toxic gas, whose main anthropogenic emission source is agriculture, apart from that which escapes into the air in cities, coming from motor vehicles, and that originating in industrial plants. Nitrogen dioxide - also known as nitrous oxide - is the main atmospheric pollutant of all the NOx and has harmful effects on human health and the environment. Among the natural emission sources of NOx are wildfires and volcanic activity.