Click the colors above to learn about their meanings. For more information about the the Air Quality Index and air pollution go to the Environmental Protection Agency's Air Now Web site . You may also hear a recorded message of the daily AQI for the Minneapolis-St. This value places it in the Moderate catagory. There are no health implications for AQI values less than 100.
Ozone is formed when nitrogen oxides and certain hydrocarbons combine in the presence of sunlight.
Produced mainly from automobiles, ozone is one component of photochemical smog. It can affect the tissues in plants and is irritating to the eye, nose, throat and respiratory systems. SO2 is a heavy, pungent, colorless gas formed primarily by the combustion of fossil fuels. Sulfur dioxide can affect the respiratory tract as well as vegetation and other materials. Coal, with high amounts of sulfur, must usually be cleaned before or during burning in order to meet clean air standards.