CO is produced when fuels are burned. Carbon monoxide levels in the Valley have dropped by more than 50 percent since 1984. Improvements are attributed to cleaner engines, cleaner fuels, the vehicle emission inspection program, and a variety of other programs that improve traffic flow and reduce driving. Carbon Monoxide robs the blood of oxygen. In addition to vehicles and off-road equipment, sources of VOCs include paints, solvents, consumer products, and industrial activities.
Ozone is primarily a summer air pollution problem.
Ozone irritates and damages the lungs. Particulate Matter Particulate matter is tiny airborne particles, most of which are dust and soot. Half of these particles come from vehicle tailpipes, and the remainder is mostly dust from paved roads, construction activities, etc. The smallest particles, which come primarily form vehicle exhaust, make up the majority of the Brown Cloud. The highest concentrations tend to be found in the Phoenix urban core.