DEEP: Ozone Information


Ozone is a colorless gas that is a major constituent of smog. This pollutant alone contributes to the majority of unhealthy air quality days in CT, as measured by the Air Quality Index (AQI). Ozone is found both at high altitude and ground level. High altitude ozone is beneficial because it shields the earth from the sun's ultraviolet radiation. Ground level ozone is harmful because it reacts with the mucus membranes of the respiratory system and causes inflammation.

Ozone forms in the air from other pollutants: volatile organic compounds (VOCs) and nitrogen oxides (NO and NO2) in the presence of ultraviolet (UV) radiation. Ozone does not come directly from any source. The VOCs that form ozone come from vehicle and industrial exhaust as well as evaporation of gasoline, solvents and paints, and many other sources.

Ozone Fact Sheet

Annual Summary of Ozone Monitoring Data

Air Quality Trends - Ozone

EPA Analysis of National and Regional Ozone Trends

Ozone Planning Efforts

Related Information

Daily Air Quality Index