Some air pollutants are visible. Some are invisible. All of them are harmful to people and plants, pollute waterways and cause global warming.
Ironic, if some pollutants get into the atmosphere naturally, most of it is put into the atmosphere by humans.
Examples of invisible pollutants:
1) nitrogen oxides
2) sulfur dioxide
3) volatile organic compounds
4) carbon monoxide
5) natural gas
6) chemicals like benzene and butadiene
Examples of visible pollutants:
1) Haze
2) Smoke
3) Dust
4) Ozone plumes