How is Ozone Transported?
Ozone is usually not formed at the point where the precursors, hydrocarbons and oxides of nitrogen, are emitted. Rather, these chemicals are typically carried some distance on the wind before the right mix and conditions for ozone formation are achieved. Pollutants in one area can contribute to ozone problems in other areas. In regions of the country where several urbanized areas are located close to each other, such as the northeast coastal region, ozone in one part of the area may be caused by a combination of ozone precursors emitted locally and those emitted in other, upwind areas. For example, NOx from an upwind source may combine with locally generated HC to form ozone in a particular area. This means that ozone precursors and ozone itself can move over large areas causing problems wherever the winds take them. Thus, ozone is a regional problem rather than a local problem.
