Oxides of Nitrogen (NOx)
Oxides of nitrogen are produced by high temperature
combustion of fossil fuels. Nitrogen oxide is the most common form
of these oxides but it quickly converts to nitrogen dioxide (NO2) on
exposure to the atmosphere. NO2 is a reddish-brown coloured gas
with a strong smell. It causes acid rain and can cause respiratory
problems in people. It also helps produce ground level ozone, a
major component of smog. Alberta
Environment guidelines for NO2
are an average of 210 parts per billion (ppb) over 1 hour, 110 ppb over
a 24 hour period and annual averages of 30 ppb.
In Alberta well over 40% of emissions of oxides of nitrogen come from transportation sources, primarily cars. Just less than 20% comes from power plants and about 35% from industrial sources. Oxides of nitrogen are measured using chemiluminescence. Nitrogen oxide mixed with ozone will produce nitrogen dioxide, oxygen and light. The more light that is produced, the higher the concentration of oxides of nitrogen.