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New England Experienced Fewer Smog Days During Recent Summer

Release Date: 10/02/2006
Contact Information: David Deegan, (617) 918-1017

(Boston, Mass. - Oct. 2, 2006) – As the 2006 summer ozone season comes to an end, EPA today confirmed that New Englanders experienced a decrease in the number of poor air quality days this year, compared to 2005. Based on preliminary data collected May through September, there were 16 days when ozone monitors in New England recorded concentrations above the health standard. By contrast, in 2005, there were a total of 26 unhealthy ozone days.

The number of unhealthy ozone days in each state this summer were as follows: 13 days in Connecticut (compared to 20 in 2005); 11 days in Massachusetts (20 in 2005); 3 days in Rhode Island (8 in 2005); 2 days in New Hampshire (4 in 2005); 1 day in Maine (4 in 2005); and no days in Vermont (no days in 2005).

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 smog, and many areas of New England had fewer days exceeding 90 degrees this summer than during the summer of 2005. Ground-level ozone, the main ingredient of smog, is unhealthy when average concentrations exceed 0.08 parts per million over an 8-hour period. Over the long-term, New England has experienced a decreasing number of ozone days, and peak ozone concentrations have decreased significantly over the last 30 years. In 1983, New England had 90 unhealthy days, compared with 16 this summer. Overall, ozone concentrations in New England have decreased by more than 20 percent since 1980.

“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.

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.

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

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 will 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 will reduce NOX and particulate matter emissions by up to 95 percent. In addition, EPA is requiring a 97 percent reduction in the sulfur content of highway diesel fuel. This diesel fuel has already been widely distributed, and starting on October 1, 2006, must be available at retail stations for these cleaner vehicles.

The record demand for electricity this summer is also a factor contributing to air pollution. High electricity demand worsens air quality by forcing power plants in the region to run near peak capacity, thus increasing air emissions from those plants. Preliminary data shows that regional electricity use reached record levels on July 18, August 1, and August 2, with the highest usage of 28,021 megawatts occurring on August 2, 2006. Unhealthy ozone levels were experienced in New England on all three of these record energy demand days.

EPA is working to address the air pollution challenges resulting from this increase in energy demand. In March 2005, EPA issued the Clean Air Interstate Rule (CAIR) to help reduce the transport of air pollution from power plants across state boundaries. When fully implemented, CAIR will reduce power plant NOX emissions by over 60 percent and sulfur dioxide emissions by over 70 percent from 2003 levels.

Also, additional improvements in air quality are expected as states implement plans to meet the 8-hour ozone standard. In 2004, EPA formally designated areas that are not complying with the 8-hour ozone standard. Connecticut, Massachusetts, and Rhode Island, are out of compliance with the ozone standard. These three states must submit plans by mid 2007 that will outline how they will meet the standard by the end of 2009.

More information:

A map showing all the 8-hour ozone nonattainment areas in New England (

The daily air quality index forecast ( including information on pollution from fine particles (soot) that is a year-round concern

Historical charts of unhealthy air days from 1983 through 2006 (

A preliminary list of the unhealthy readings recorded this summer ( by date and monitor location

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