Which is a major source of air pollution created by humans?

Air pollution is defined as the presence of or introduction of harmful or toxic substances into the air. 

Most of the air pollution that is created by humans is due to the emission of burning fossil fuels into the air.Fossil fuels are buried geologic deposits of organic materials, formed from decayed plants and animals that have been exposed to heavy pressures of and heat in the Earth's crust over hundreds of millions of years. Examples...

Air pollution is defined as the presence of or introduction of harmful or toxic substances into the air. 

Most of the air pollution that is created by humans is due to the emission of burning fossil fuels into the air. Fossil fuels are buried geologic deposits of organic materials, formed from decayed plants and animals that have been exposed to heavy pressures of and heat in the Earth's crust over hundreds of millions of years. Examples of fossil fuels include crude oil, natural gas, gasoline, and coal. When such fuels are burned and released into the atmosphere they block the Sun's radiation that reflects off of the Earth's surface. Thus, the radiation is not able to leave Earth's atmosphere and is converted into heat energy. This is one source of global warming.