Some types of air pollution include Smog, Acid Rain and Nuclear Problems. Smog can harm health, damage the environment and cause poor visibility. Smog is often worse away from the source of the smog-forming chemicals, since the chemical reactions that result in smog occur in the sky while the reacting chemicals are being blown away from their sources. The combustion of coal, oil, and gasoline accounts for much of the airborne pollutants.
Industry is a big contributor of ozone into the atmosphere.
Ozone levels may ironically be as high or higher downwind from cities than in the cities themselves, reflecting the time needed for the atmospheric photochemical reactions to occur.