Human: What is air pollution, and what are the causes of it? Assistant: 
Air pollution is a type of pollution that occurs when harmful substances – typically chemical compounds or particles – are released into the atmosphere. These pollutants can come from both naturally occurring phenomena like dust and smoke, as well as from human activities such as burning fossil fuels, manufacturing processes and transportation. Common causes of air pollution include the burning of fossil fuels, vehicle exhaust, power plants, industrial and agricultural processes, and deforestation. Burning of plastics, aerosol cans and other materials in open fires can also contribute to air pollution.