When coal and oil burn, the sulfur in them combines with oxygen in the air to make sulfur oxides. Processing mineral ores that contain sulfur and industrial burning of fossil fuels are also sources of sulfur oxides in the atmosphere.
How is nitrogen oxide produced?
Nitrogen oxides are produced in combustion processes, partly from nitrogen compounds in the fuel, but mostly by direct combination of atmospheric oxygen and nitrogen in flames. Nitrogen oxides are produced naturally by lightning, and also, to a small extent, by microbial processes in soils.
Where do nitrogen oxides come from?
Nitrogen oxides are produced from the reaction of nitrogen and oxygen gases in the air during combustion, especially at high temperatures. At normal temperatures, oxygen and nitrogen gases do not react together. Nitrogen oxides are produced naturally from a lightning strike.