NOx is the generic term for a group of highly
reactive gases, all of which contain nitrogen
and oxygen in varying amounts. [such as nitric
oxide (NO) and nitrogen dioxide
Many of the nitrogen oxides are colorless and
odorless. However, one common pollutant, nitrogen
dioxide (NO2) along with particles
in the air can often be seen as a reddish-brown
layer over many urban areas.
Nitrogen oxides form when fuel is burned [...].
The primary sources of NOx are motor vehicles,
electric utilities, and other industrial, commercial,
and residential sources that burn fuels.
In the atmosphere, nitrogen oxides can contribute
to formation of photochemical
ozone (smog) and have
health consequences. They also lead to acid
rain and contribute to global warming.