The Environmental Protection Agency today confirmed that New Englanders experienced a decrease in the number of unhealthy air quality days this year, compared to 2010. The decrease in number of days with unhealthy air quality is related to weather conditions and because emissions of the chemicals that create ozone continue to decline.
Based on preliminary data collected between April and September 2011, there were 16 days when ozone monitors in New England recorded concentrations above levels considered healthy. By contrast, in 2010 there were a total of 28 unhealthy ozone days.
The number of unhealthy ozone days in each state this summer are as follows:
- 14 days in Connecticut (compared to 24 in 2010)
- 10 days in Massachusetts (14 in 2010)
- 6 days in Rhode Island (6 in 2010)
- 3 days in Maine (8 in 2010)
- 2 days in New Hampshire (8 in 2010)
- 1 day in Vermont (0 in 2010).
The decrease in the number of days with unhealthy air this year was directly related to the decrease in the number of hot days this year. Sunlight and high temperatures speed the formation of ground-level ozone smog. For example, at Bradley Airport near Hartford, Conn. there were 34 days when the temperature was at or above 90°F, during the summer of 2010, compared to only 15 such days this year.
Although the number of unhealthy days may vary from year to year due to weather conditions, 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 16 this summer.
A major factor in the long-term decline in unhealthy days is the substantial decrease in air pollution emissions. For example, since 2004, new cars, SUVs, pickup trucks, and mini-vans have stringent new emission standards resulting in vehicles that are 77 to 95 percent cleaner than older models. In addition, to further reduce air pollution, on July 7, 2011, EPA announced the Cross-State Air Pollution Rule, that requires 27 states to significantly reduce power plant emissions that contribute to ozone and/or fine particle pollution. By 2014, combined with other final state and EPA actions, the new rule will reduce power plant sulfur dioxide (SO2) emissions by 73 percent and nitrogen oxide (NOx) emissions by 54 percent from 2005 levels.
Ground-level ozone is the main ingredient of smog. In 2008, EPA made the ozone standard more stringent. Ozone levels are unhealthy when average concentrations exceed 0.075 parts per million over an 8-hour period. Ground-level ozone is formed when volatile organic compounds and oxides of nitrogen, chemically react in the presence of sunlight. Cars, trucks, motorcycles and buses give off the majority of the pollution that makes smog. Fossil fuels burning at electric power plants, which run at high capacities on hot days, emit substantial 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.
Although the 2011 ozone season is ending, pollution from small particles in the air is a year-round concern. The daily air quality index forecast will continue to be available (http://www.epa.gov/ne/aqi/). New Englanders can also sign up at this address to receive air quality alerts. These alerts are issued by e-mail, whenever necessary, to notify program participants when high concentrations of ground-level ozone or small particles are predicted to occur, in their area.
Historical charts of unhealthy air days from 1983 through 2011 are available for each New England state on EPA New England’s web site at: www.epa.gov/ne/airquality/standard.html. 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: www.epa.gov/region1/airquality/o3exceed-11.html.