Massachusetts Agency Records Moderate Increase in Amount of Unhealthful Air Days

The close of the 2007 summer ozone season occurred Sept. 30th, and for the year, Massachusetts recorded a moderate increase in the total number of unhealthful summer air days compared to 2006, officials announced on Oct. 4.

The Massachusetts Department of Environmental Protection (DEP), which tracks daily ozone readings from April through September (and fine particle readings through the year), recorded ground level ozone in excess of the 8-hour national standard at one or more of its monitors on 20 days this year.

Most of the harmful ozone around us is created when hydrocarbons -- the main ingredients in gasoline and solvents -- chemically react on hot, sunny days with nitrogen oxides, which are produced when fuels are burned. Meteorologically, the period May through September 2007 was (on average) somewhat hotter and drier than normal, which provided more opportunity for ground-level ozone to build to levels that exceed the federal standard.

"Summertime smog can be harmful to us all, but the effect is more acute in children, and people with respiratory disease -- asthma for example -- and those who work or exercise outdoors," DEP Commissioner Laurie Burt said. "Providing this information to the public is why MassDEP monitors air quality continually throughout the summer and issues alerts when ground-level ozone is expected to reach unhealthful levels."

While the ozone season ended Sept. 30, MassDEP will continue to issue forecasts for fine particulate matter. For more information, contact DEP at

This article originally appeared in the 10/01/2007 issue of Environmental Protection.