Smog is a kind of air pollution; the word "smog" is a portmanteau of smoke and fog. Classic smog results from large amounts of coal burning in an area caused by a mixture of smoke and sulfur dioxide. Modern smog does not usually come from coal but from vehicular and industrial emissions that are acted on in the atmosphere by sunlight to form secondary pollutants that also combine with the primary emissions to form photochemical smog.

The United States Environmental Protection Agency has designated over 300 U.S. counties to be non-attainment areas for one or more pollutants tracked as part of the National Ambient Air Quality Standards. These areas are largely clustered around large metropolitan areas, with the largest contiguous non-attainment zones in California and the Northeast. Various U.S. and Canadian government agencies collaborate to produce real-time air quality maps and forecasts. Have been made a effect on humans.

Being in a low basin surrounded by mountains, Los Angeles is notorious for its smog. The millions of vehicles in the city plus the added effects of the Los Angeles/Long Beach port complex contribute to further air pollution in the city. While strict regulations by the Californian government have reduced the number of Stage 1 smog alerts from several hundred annually to just a few annually, Los Angeles' pollution level still exceeds health standards and is a pressing issue for the more than 15 million people who live there. L.A is the most resantly city that it has happened to. I dont want smog to happen in celeste. www.google.com/smog