Sources of Air Pollution There are a number of sources of air pollution. But in urban areas throughout our state, motor vehicle emissions account for up to 40 percent of the pollutants that are toxic or noxious to people. Most of these pollutants come from cars, buses and trucks that aren't operating efficiently. It is especially dangerous to unborn and newborn children. A significant source of particulate matter is diesel exhaust.
Vehicles are the largest source of NOx.
Hydrocarbons are volatile organic compounds emitted primarily through fuel combustion from motor vehicles. They are toxic to human health, and readily combine with other pollutants to form ozone. Ground-level ozone is produced when emissions from motor vehicles and industry combine with sunlight on hot days. Ozone irritates eyes, nose, and throat, aggravates heart and lung diseases, and decreases lung function. Unlike the ozone in the upper atmosphere which protects the earth from the sun's harmful ultraviolet rays, ground-level ozone has no beneficial effects.