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New England Experienced Fewer Smog Days During Recent Summer

Release Date: 09/22/2008
Contact Information: David Deegan, (617) 918-1017

(Boston, Mass. – Sept. 22, 2008) – As the 2008 summer ozone season comes to an end, EPA today confirmed that New Englanders experienced fewer poor air quality days this year, compared to 2007. Based on preliminary data collected this April through September, there were 28 days when ozone monitors in New England recorded concentrations above the health standard. By contrast, in 2007, there were 53 unhealthy ozone days.

The number of unhealthy ozone days in each state this summer was:
- 22 days in Connecticut (compared to 42 in 2007)
- 18 days in Massachusetts (38 in 2007)
- 8 days in New Hampshire (22 in 2007)
- 6 days in Rhode Island (18 in 2007)
- 4 days in Maine (14 in 2007)
- 3 days in Vermont (5 days in 2007)

This year's decrease in the number of days with unhealthy air was directly related to the decrease in the number of hot days, combined with the longer-term decline in air pollution emissions causing ozone smog. Sunlight and high temperatures speed the formation of ground-level ozone, and most areas in New England had fewer days exceeding 90 degrees this summer than last summer. In addition, this summer there were many days with heavy showers and thunderstorms that helped keep ozone levels low.

Over the long-term, New England has experienced a decreasing number of unhealthy ozone days, and peak ozone concentrations have decreased significantly over the last 30 years. In 1983, New England had 113 unhealthy days, compared with 28 this summer, for a decrease of 75 percent.

“When we look back to the air quality conditions a generation ago, we can feel proud of the advances we’ve made in reducing air pollution in New England,” said Robert W. Varney, regional administrator of EPA’s New England regional office.

Earlier this year, EPA lowered the level of the ozone air quality health standard to 0.075 parts per million (ppm) on an 8-hour average basis. For comparison purposes, all statistics on the number of unhealthy days are presented in relation to the new standard.

Exposure to elevated ozone levels can cause serious breathing problems, and aggravate asthma and other pre-existing lung diseases.

Ground-level ozone is formed when volatile organic compounds and oxides of nitrogen chemically react in the presence of sunlight. Cars, trucks and buses give off the majority of the pollution that makes smog. Fossil fuel burning at electric power plants, which run at high capacities on hot days, gives off significant amounts of air pollution. Gas stations, print shops, household products like paints and cleaners, as well as gasoline-powered lawn and garden equipment, also contribute to ozone formation.

EPA has taken a number of steps to further reduce air pollution. Since 2004, new cars, sport utility vehicles, pickup trucks, and mini-vans are meeting stringent new emission standards. The requirements continue to be phased in through 2009 resulting in vehicles that are 77 to 95 percent cleaner than older models. The program also requires a 90 percent reduction in the sulfur content of gasoline. Beginning with model year 2007, EPA’s standards for new diesel trucks and buses reduce NOX and particulate matter emissions by up to 95 percent. In addition, EPA required a 97 percent reduction in the sulfur content of highway diesel fuel, beginning in 2006.

Furthermore, additional improvements in air quality are expected as states implement plans to meet the new ozone standard. In 2010, EPA plans to formally designate areas that are not complying with the 0.075 ppm 8-hour ozone standard. These states will then be required to submit plans that outline how they will meet the standard.

Although the 2008 ozone season has ended, pollution from fine particles (soot) in the air is a year-round concern. The daily air quality index forecast will continue to be available on EPA’s web site.

More information:
Daily Air Quality index (
Sign up for daily air quality alerts (
Historical air quality data in New England (1983–2008) (
A preliminary list of the unhealthy readings recorded this summer by date and monitor location (

09/29/08 : Press Release updated to reflect updated accurate information.
- Changed Vermont 2007 exceedence from "0" days to "5" days, due to data transcription error at EPA (5-day figure for 2007 is based on current, revised air quality standard, not the earlier air quality standard that was in place during 2007 ozone season).
- Changed Maine 2008 exceedence from "3" days to "4" days, based on updated information from Maine DEP