The Environmental Protection Agency has established a maximum ozone health standard. A single hour of exposure to ozone at this level is sufficient to cause negative respiratory effects. During heavy exercise these people are at particular risk for short-term health effects. Many more individuals maybe repeatedly exposed to lower ozone levels which may cause long- term adverse effects. About 64 million people live in areas with ozone levels greater than the maximum health standard.
Ozone reduces the ability of trees and plant to fight disease.
Ozone has been shown to damage various tree seedling. The Clean Air Act of 1990 requires EPA, states, and cities to implement a series of programs that will further reduce emissions of ozone-causing VOCs and NOx from cars, fuels, industrial and chemical facilities, power plants, and consumer and commercial products among other sources. Cleaner cars and fuels, new kinds of gasoline nozzles, enhanced vehicle inspection, and other programs will be phased in over the next decade. Ozone is naturally produced and destroyed at a constant rate in the stratosphere. These ozone depleters degrade slowly and can remain intact until they reach the stratosphere.