Within the MDAQMD's boundaries, sources of air pollution range from a large mining operations to the corner gas station. By far, the largest contributor of air pollution within District boundaries is motor vehicles. The chart below shows emission sources of r oxides of nitrogen, one of the main precursors for ozone formation.
As demonstrated above, NOx from on-road vehicles - which include light and heavy duty motor vehicles operating on roads, highway ramps and during idling that use gasoline diesel and other fuels - account for 40% of these types of emissions within the MDAQMD. NOx emissions from Stationary Sources - which includes factories, boilers, cement plants and power plants - account for only 27% of the MDAQMD's inventory.
Although many of the substances classified as pollutants do occur naturally at low concentrations, much higher and unhealthful levels can be created by human activity. Click here to read about common air pollutants, their sources and health effects.. Click here to read about common air pollutants, their sources and health effects.