Clean air, EJ, and facility siting in the Phoenix Metropolitan Area

Abstract

As in virtually all large urbanized areas in the US, air quality in the Phoenix Metropolitan Area (PMA) is largely determined by the mix of six common pollutants in the atmosphere: ground-level ozone, particulates, carbon monoxide, nitrogen oxides, sulfur dioxide, and lead. Air pollution is a mixture of these contaminants and is a major environmental risk to health (see Table 3.1).1 Ground-level ozone results from a chemical reaction between pollutants such as nitrogen oxides and volatile organic compounds (VOCs) in the presence of heat and sunlight. Exhaust from vehicles, industrial emissions, gasoline vapors, and chemical solvents are major sources of nitrogen oxides and VOCs. Ozone (O3) is a major constituent in smog. Particulates, or particulate matter (PM), include dust, soot, dirt, smoke, and liquid droplets suspended in air. Some particulates occur naturally, originating from volcanoes, dust storms, forest and grassland fires; others are manmade, originating as a result of human activities such as the burning of fossil fuels in vehicles, power plants, various industrial processes, fertilizer production and livestock operations.2 Carbon mon- oxide is a colorless, odorless gas generated from vehicle exhaust, wood burning, forest fires, and manufacturing processes. Nitrogen oxides are a group of highly reactive gases. Of particular concern is nitrogen dioxide