What are ground-level ozone and ozone transport?
Although it acts as a protective layer high above the earth, ground-level ozone can be harmful to breathe. Ozone is the prime ingredient of smog; it is not emitted directly into the air but rather is formed by gases called nitrogen oxides (NOx) and volatile organic compounds (VOCs). In the presence of strong sunlight, these gases react with oxygen in the air to form ozone concentrations that can remain high over large regions. Certain urban areas tend to have high ozone levels. However, areas downwind of urban settings are also subject to high ozone exposure, as winds carry VOCs and NOx from their original sources. The process of ozone traveling to these downwind areas is referred to as ozone transport. It is especially significant in certain areas of the eastern United States, including the “northeast corridor” (roughly, from Washington, D.C. to Boston) and the vicinity of Lake Michigan. In these areas, transport of ozone to downwind areas, even across state boundaries, can contribute
