Final answer:
Smog, a type of atmospheric pollution, is primarily caused by emissions from vehicles and industrial activities, comprising substances like sulfur dioxide, particulate matter, and ozone.
Step-by-step explanation:
Smog is a kind of atmospheric pollution caused mainly by exhaust and emissions from vehicles and industrial processes. There are two main types of smog: industrial and photochemical. Industrial smog primarily comes from the burning of fossil fuels like coal and oil, and contains pollutants such as sulfur dioxide and particulate matter.
On the other hand, photochemical smog is formed when sunlight drives chemical reactions between primary pollutants from automobiles and normal atmospheric compounds, producing a mix of over 100 different chemicals with ozone being the most abundant. Catalytic converters in gas powered vehicles help to reduce these emissions. Efforts in green chemistry and industrial ecology also play a role in reducing smog formation.