In the Valley of the Sun Valley air pollution comes from several sources but most comes from vehicles.
Air pollution is influenced by wind, weather, and topography.
The Valley is a broad, shallow basin surrounded by mountains. The topography and mild desert climate make the Valley more vulnerable than most major metropolitan areas to stagnant air conditions. Temperature inversions and stagnation occurs when cooler air and pollution is trapped close to the ground. Vehicle miles traveled are increasing even faster than population is increasing in the Valley. CO is produced when fuels are burned.