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EPA's End-of-Season Ozone Data Show Increase in Bad Air Days

Release Date: 10/01/2001
Contact Information: Amy Miller, EPA press office (617) 918-1042

BOSTON – At the close of the 2001 summer ozone season, the U.S. Environmental Protection Agency announced that warm weather this summer caused New England to suffer more unhealthy air quality days than last summer, which was unseasonably cool.

Based on preliminary data, there were 31 days when ozone monitors in New England recorded concentrations above the level considered healthy. Last summer, there were a total of 19 unhealthy days. Ground level ozone, the main ingredient of smog, is unhealthy when average concentrations exceed .08 parts per million over an eight-hour period.

The number of unhealthy days in each state this summer were as follows: 25 days in Connecticut (compared to 13 in 2000); 27 days in Massachusetts (5 in 2000); 15 days in Rhode Island (8 in 2000); 15 days in Maine (3 in 2000); 10 days in New Hampshire (1 in 2000); and 2 days in Vermont (1 in 2000). In addition, Maine, Massachusetts, and Rhode Island saw more unhealthy days this summer than in any individual year in the past 10 years.

Although warmer temperatures this summer led to more unhealthy days, the long-term trend in the number of unhealthy days in New England is downward. Historical charts of unhealthy air days from 1983 through 2001 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:

"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, EPA's New England administrator. "A summer like this one, however, reminds us that our efforts to use cleaner cars and fuels and our commitment to reducing power plant emissions must continue. Too many New Englanders, especially children and those with respiratory illnesses, still suffer from unhealthy levels of air pollution during the summer months."

Progress in reducing the number of unhealthy days has been made as a result of air pollution control programs, such as cleaner cars, cleaner fuels, and more stringent controls on industrial pollution. Some of our progress, however, has been offset by a number of factors, including an increasing amount of vehicle miles traveled on New England's roads. Data collected by the New England states indicate that vehicle miles traveled has increased by about 15 percent over the last 10 years. The popularity of light duty trucks and sports utility vehicles is another factor offsetting our pollution reduction gains. Almost half of the passenger vehicles sold today are higher-polluting light-duty vehicles, such as sport utility vehicles (SUVs), minivans, vans and pick-up trucks.

EPA is working to address the challenges posed by these mobile source emissions. For example, EPA has issued tougher tailpipe emission standards for cars and light-duty vehicles, including sport utility vehicles that will begin in 2004. These new standards for the first time ensure that SUV's, mini-vans and light-duty trucks meet the same low levels of tailpipe emissions as other passenger cars. Also, heavy duty diesel trucks will be required to meet new very stringent standards in 2007. In addition, EPA is asked companies to join our Commuter Choice Leadership Initiative, which is a voluntary, national standard of excellence for employer-provided commuter benefits. Companies that meet the national standard provide incentives for employees to commute to and from work using alternatives means of transportation such as mass transit, biking, walking, and van pools.

The record demand for electricity this summer is also a factor since emissions are highest on days when all of the power plants in the region are running near peak capacity. According to the operators of the New England power grid, the four highest days of demand in history occurred on Aug. 7 to Aug. 10. This year's all-time record demand of 25,158 megawatts (MW) set on Aug. 9 eclipsed the previous all-time record of 22,544 MW set on July 6, 1999 by almost 12 percent. This is the same day that very unhealthy levels of ozone were recorded in coastal areas of Connecticut in excess of 150 percent of EPA's air quality standard.

EPA is working to address the air pollution challenges resulting from this increase in energy demand. EPA has taken aggressive steps to reduce pollution from power plants upwind of New England. These actions will result in an additional reduction of about 1 million tons of nitrogen oxides from power plants in the eastern United States by 2004. In addition, EPA is working with Congress to develop national legislation aimed at reducing multiple types of air pollutants emitted by power plants. This legislation is expected to establish mandatory reduction targets for sulfur, nitrogen oxide, and mercury. Furthermore, EPA's Energy Star program provides information and tools to help consumers and businesses improve their energy efficiency, save money, and reduce air pollution. Investments already made by the hundreds of New England businesses and public entities participating in Energy Star will save $1.9 billion dollars and billions of kilowatt-hours of electricity, while at the same time reducing air pollution equivalent to 42.2 billion pounds of carbon dioxide, 77.8 million pounds nitrogen oxides, and 166.5 million pounds of sulfur dioxide.

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

Ground-level ozone (smog) is formed when volatile organic compounds and oxides of nitrogen interact 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 lawn and garden equipment, also contribute to smog formation.

To inform New Englanders about ozone levels, EPA maintains an ozone mapping system that shows "real-time" images and daily forecasts of ground-level ozone levels. The daily ozone forecast is available from May through September on the EPA's air pollution information web page at Citizens can also sign up at this web address to receive free smog alerts from EPA's New England office.