According to the Union of Concerned Scientists, coal is the single biggest air polluter in the United States. America gets 54% of its electricity from coal and there is about 600 coal plants in the US. Consider that one coal plant burns 1.4 million tons of coals each year it pollutes when mined, transported, stored and burned. Its air pollution causes smog, soot, acid rain, global warming, and toxic air emissions.

According to the World Health Organization, the most common sources of air pollution are: particulate matter, ozone, nitrogen dioxide, and sulphur dioxide. Air pollution is estimated to have cause approximately 3.3 million deaths worldwide. The major causes of air pollution are industry and vehicles. National Ambient Air Quality Standards (NAAQS) are determined by the health effects of SO₂, NO_x, PM₁₀, PM_2.5, lead, ozone, and carbon monoxide. For the most part the US meets and exceeds air pollution standards.