Final answer:
Air pollution refers to the introduction, into the atmosphere, of harmful substances that have negative effects on humans, other organisms, and the environment. Major sources of air pollution include vehicles and industrial processes. Smog is a specific type of air pollution that often forms over urban areas.
Step-by-step explanation:
Air pollution refers to the introduction, into the atmosphere, of substances that have harmful effects on humans, other living organisms, and the environment either as solid particles, liquid droplets or gases. Major sources of air pollution include gas emissions from fossil fueled vehicles and their reaction products (CO, NOx, Ozone) as well as particulate matter, SO₂, and VOCs. Examples of toxic air pollutants include benzene, perchloroethylene, methylene chloride, dioxin, asbestos, toluene, and metals such as cadmium, mercury, chromium, and lead compounds.
Smog is a mixture of air pollutants (sulfur dioxide, nitrogen oxides, ozone, and particulates) that often form over urban areas as a result of fossil fuel combustion. Numerous scientific studies have linked air pollution to a variety of health problems.