Air pollution occurs when the air contains pollutants such as gases, fumes and dust in harmful amounts. Air pollution can be harmful to the health of humans and animals if left unchecked.
Prior to industrialization, the ecosystem was able to take care of any discrepancies in the air through wind, rain, and other acts of nature. However, since industrialization, humans have added more pollutants into the atmosphere than the ecosystem could deal with. Pollutants pumped directly into the air are primary pollutants; for example, carbon monoxide from car exhausts is a primary pollutant. Further pollution can occur when the pollutants in the atmosphere undergo chemical reactions, which is secondary pollution.