Nitrogen dioxide (NO2)
Nitrogen Dioxide is one of a group of gases called nitrogen
oxides (NOx) which is formed during the combustion of fossil fuels.
NO2 is a reddish-brown gas with a pungent and irritating odour. It
reacts in the air with water vapour to form nitrous and nitric acid
and then toxic organic nitrates. This contributes to the production
of acid rain that can kill trees, fish and animal life
The majority of nitrogen oxides emitted from a vehicle exhaust are
in the form of nitric oxide (NO), which is not directly considered
harmful to health. However, this gas can react with other gases
present both in the exhaust and the atmosphere, to form nitrogen
dioxide. Nitrogen dioxide is harmful to health and is also an
important component of ground level ozone formation.
Whenever anything is burnt in air, nitrogen oxides are formed. This
is because the air we breathe is mostly made up of nitrogen (78%)
and oxygen (21%) and these combine when energy (from burning
material) is available.
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