The area designated by EPA that exceeds the acceptable national standard for PM
10 (particulate matter less than 10 microns) pollution levels. PM
10 includes dust, soot and other tiny bits of solid materials that are released into and move around in the air. PM
10 is produced by many sources, including exhaust from cars, trucks, buses and planes, industrial sources like power plants, fugitive dust sources like construction, mining and agricultural activities, as well as fuel combustion like the operation of fireplaces and wood stoves.
The area designated by EPA that exceeds the current acceptable national standard for ozone pollution levels. At ground-level, ozone is the primary constituent of smog. Ozone is not emitted directly into the air but is formed by the reaction of VOCs and NO
x in the presence of heat and sunlight. VOCs are emitted from a variety of sources, including motor vehicles, chemical plants, refineries, factories, consumer and commercial products, and other industrial sources. Nitrogen oxides are emitted from motor vehicles, power plants, and other sources of combustion.
The area designated by EPA that exceeds the now defunct (replaced by the 8 Hour Ozone Standard) acceptable national standard for ozone pollution levels. At ground-level, ozone is the primary constituent of smog. Ozone is not emitted directly into the air but is formed by the reaction of VOCs and NO
x in the presence of heat and sunlight. VOCs are emitted from a variety of sources, including motor vehicles, chemical plants, refineries, factories, consumer and commercial products, and other industrial sources. Nitrogen oxides are emitted from motor vehicles, power plants, and other sources of combustion.
The area previously designated by EPA that exceeded acceptable national standards for CO (carbon monoxide) pollution levels. EPA redesignated this area in attainment of the national CO standards in 2005, thus declaring the area a maintenance area as opposed to a nonattainment area. Carbon monoxide (CO) is an odorless, colorless gas. It forms when the carbon in fuels does not completely burn. Vehicle exhaust contributes roughly 60 percent of all carbon monoxide emissions nationwide, and up to 95 percent in cities. Other sources include fuel combustion in industrial processes and natural sources such as wildfires.
Area A was originally drawn by the Arizona Department of Environmental Quality (ADEQ) as the area under which the clean burning gasoline measures (emissions testing, summer and winter fuel formulations) are applicable. Since then, the boundary has been used by many other state statues, rules and ordinances (such as residential wood-burning) as the area of applicability for those respective regulations.
