The SCAQMD is the air pollution control agency for the South Coast Air basin. The Basin includes California’s largest metropolitan region including the western portions of Riverside and San Bernardino Counties, the southern two-thirds of Los Angeles County, and all of Orange County. The air basin covers 6,729 square miles, is home to more than 40 percent of California’s population, and generates about 29 percent of the State’s total criteria pollutant emissions. The California Air Resources Board has current and historic data for the South Coast, as well as the whole state, including the Latest Ozone Summary.