Ozone Monitoring Program

The Bureau of Air Quality operates and maintains a variety of ambient air monitoring equipment around the state. Some of these instruments operate on a continuous basis and provide hourly averages of pollutants or meteorological data that is used in the evaluation of the air pollutant data. Data may also be collected over a twenty-four hour period such as particulates or it may be collected as a composite over an entire week. Examples of the latter are the atmospheric and mercury deposition monitoring programs. The number of monitoring sites and the pollutants that are monitored may vary from year to year depending on the expected concentrations of the pollutants, the origin of the pollutants and new programs based on changes in existing regulations or the establishment of new regulations. Ozone is an extremely reactive gas comprised of three atoms of oxygen. Ozone exists naturally in the earth's upper atmosphere, the stratosphere, where it shields the earth from the sun's harmful ultraviolet rays. However, ozone found close to the earth's surface, called ground-level ozone, is a component of smog and a harmful pollutant. Sponsor: Maine Department of Environmental Protection, United States Environmental Protection Agency, National Park Service - Air Resources Division