MARAMA Mid-Atlantic Regional Air Management Association

Mapping Ground Level Ozone

Ozone is the major component of summertime smog in the Mid-Atlantic Region. Ozone in the upper atmosphere is beneficial to life, shielding the earth from harmful ultraviolet radiation from the sun. In contrast, a high concentration of ozone in the air we breathe is a major health and environmental concern.

Ozone is formed when sunlight provides energy for chemical reactions between airborne volatile organic compounds and nitrogen oxides. Ozone can be formed miles downwind from sources of these pollutants, and high concentrations of ozone can occur over large areas.

The Ozone Map is created daily in the summertime from actual measurements of ozone throughout the Mid-Atlantic and Northeast Regions. It is updated two or three times each day and shows ozone as it builds up and moves downwind. It is the best source of information about where ozone levels are reaching unhealthful levels. During the summertime, the Ozone Map is also linked to forecasts prepared by some states and EPA. These forecasts predict whether air quality will be unhealthful tomorrow.

The ozone map was originally used in the Baltimore-Washington area in 1995 and was also used in New Jersey in 1996. Through a collaborative effort between MARAMA, NESCAUM (the Northeast States for Coordinated Air Use Management—our sister organization for the northeastern states), the Ozone Transport Commission, and the U.S. Environmental Protection Agency, a mapping system for the entire northeast was developed in 1997. In 1998 EPA developed the map for a larger area of the U.S.

To view the ozone map and related information please go to the EPA's Ozone Map Web Site. Further information about the map, including examples from summer 1997, can be found on EPA New England’s Web Site. The Maryland Department of the Environment’s Web Site also has related information.