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New England States Experienced Fewer Smog Days During Recent Summer

Release Date: 09/30/04
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Contact: David Deegan, 617-918-1017

For Immediate Release: September 30, 2004; Release # 04-09-20

BOSTON – As the 2004 summer ozone season comes to an end, the EPA today confirmed that New Englanders experienced fewer poor air quality days this year than in 2003. Based on preliminary data collected between May and September, there were 13 days when ozone monitors in New England recorded concentrations above levels considered healthy. By contrast, in 2003 a total of 17 unhealthy ozone days occurred.

The number of unhealthy ozone days in each state this summer were as follows: Eight days in Massachusetts (compared to 11 in 2003 and 30 in 2002); Six days in Connecticut (14 in 2003 and 36 in 2002); Four days in Rhode Island (10 in 2003 and 17 in 2002); Four days in New Hampshire (one in 2003 and 13 in 2002); One day in Maine (five in 2003 and 17 in 2002); and One day in Vermont (none in 2003 and five in 2002).

The reduced number of unhealthy days during both 2003 and 2004 was directly related to a decrease in the number of hot, sunny days during those summers, as well as the longer term decline in the air pollution emissions that causes ozone smog. Ground-level ozone, the main ingredient of smog, is unhealthy when average concentrations exceed 0.08 parts per million over an 8-hour period. The formation of ground-level ozone smog is exacerbated by sunlight and high temperatures.

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 43 days in 2002, and 17 and 13 unhealthy days during the past two cool summers, respectively. 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 pollution,” said Robert W. Varney, regional administrator of EPA’s New England regional office. “That we still experience unhealthy ozone days during cool summers emphasizes that our efforts for cleaner cars and fuels, and our commitment to reducing power plant emissions, must continue.”

Ground-level ozone (smog) 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 smog-making pollution. Gas stations, print shops, household products like paints and cleaners, as well as gasoline-powered lawn and garden equipment, also contribute to smog formation.

Exposure to elevated ozone levels can cause serious breathing problems, and aggravate asthma and other pre-existing lung diseases. It can also make people who are vulnerable more susceptible to respiratory infection. Studies have shown an association between ozone levels in the outdoor air and increased hospital admissions for respiratory causes, such as asthma. Ozone air pollution in the northeastern United States has been associated with as much as 10 to 20 percent of all summertime respiratory hospital visits and admissions.

In recent years, EPA has taken a number of steps to further reduce air pollution and implement strong, health-protective standards for different air pollutants. Stringent emission standards for passenger vehicles and new requirements for gasoline have been established. Beginning with the 2004 model-year, new cars, pick-up trucks and sport utility vehicles are 77 to 95 percent cleaner than vehicles already on the road. EPA has also set stringent standards for heavy duty trucks and buses. Beginning in 2004, heavy duty trucks and buses are emitting 40 percent less nitrogen oxides (NOx). In 2007, these vehicles will be required to meet even more stringent standards and use cleaner fuel that will reduce both particulate matter and NOx emissions by more than 90 percent.

Last May, EPA adopted tough standards for new nonroad diesel engines used in construction, agricultural, and industrial equipment, as well as the fuel used in these vehicles. The combination of cleaner engines and fuel will reduce pollution from these engines by 90 percent starting in 2008. EPA also has set emission standards for lawn and garden equipment, marine engines and locomotives.

In January 2004, EPA proposed the Clean Air Interstate Rule, which focuses on states whose sulfur dioxide and NOx emissions are significantly contributing to fine particle and ozone pollution problems in other downwind states. The proposed Clean Air Interstate Rule covers 29 states in the Eastern U.S. and the District of Columbia. By 2015, this rule is expected to reduce NOx emissions by approximately 1.8 million tons, and virtually eliminate acid rain.

The Agency has also taken aggressive steps to quickly reduce pollution from power plants in the eastern United States. Nineteen eastern states and the District of Columbia adopted and implemented the NOx Budget Trading Program which established emission caps on the amount of nitrogen oxide that can be emitted from power plants and other large combustion sources during the ozone season (May through September each year). These emission caps were expected to reduced NOx emissions by about 600,000 tons this year.

Additional improvements in air quality are expected as states begin to implement plans to meet the new 8-hour health-based ozone standard. The first step in this process occurred in April when EPA formally designated areas that are not complying with this standard. All of Connecticut, Massachusetts and Rhode Island, as well as parts of New Hampshire and Maine, are out of compliance. States with these nonattainment areas must submit plans by 2007 that will outline how they will meet the 8-hour ozone standard. A map showing the 8-hour ozone nonattainment areas in New England can be found at: .

Although the 2004 ozone season has ended, pollution from small particles in the air is a year-round concern. The daily air quality index forecast will continue to be available at New Englanders can also sign up at this address to receive air quality alerts. These alerts are issued by e-mail or fax, whenever necessary, to notify program participants when high concentrations of ground-level ozone or fine particles are recorded, or are predicted to occur, in their area.

Historical charts of unhealthy air days from 1983 through 2004 are available for each state on EPA New England’s web site at: A preliminary list of the unhealthy readings recorded this summer by date and monitor location, and corresponding air quality maps for each day, can be found at:

Relative Information:
Unhealthy Air Days 2004
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Air Quality Index
Air Quality Web Site
Historical Data: Unhealthy Air Days 1983 - 2004