Ozone occurs in two layers of the atmosphere. In the stratosphere, ozone protects the earth from harmful ultraviolet rays. At ground-level it is an air pollutant that can be harmful to human health and the environment. Motor vehicle exhaust and industrial emissions, gasoline vapors, and chemical solvents are some of the major sources of ozone. The Clean Air Act requires EPA, states, and cities to implement programs to further reduce emissions of ozone precursors from sources such as cars, fuels, industrial facilities and power plants. The EPA also encourages lifestyle changes such as recycling and conservation that can result in significant air quality improvements.
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