This is accomplished through a comprehensive program of planning, regulation, compliance assistance, enforcement, monitoring, technology advancement, and public education. The AQMD is the air pollution control agency for the four-county region including Los Angeles and Orange counties and parts of Riverside and San Bernardino counties. It is the second most populous urban area in the United States. Many of the same factors that make living in Southern California so desirable also contribute to the worst smog problem in the nation. Gentle ocean breezes carry pollutants into the inland valleys where they are trapped by the surrounding mountains.
Thermal inversions act like a lid over the basin.
Bright sunshine and warm temperatures cause some pollutants to react with each other, forming even more pollution. These natural conditions, along with the pollution from over 9 million motor vehicles, thousands of businesses and industries, and countless consumer products, create an ideal smog factory. Because this area's smog problem is so severe, AQMD often finds itself at the forefront of the nation's efforts to reduce air pollution. WHAT AQMD DOES AQMD is responsible for controlling emissions from stationary sources of air pollution. These can include anything from large powerplants and refineries to the corner gas station.