More Heat Means More Smog, Breathing Problems

Residents of cities in the eastern and southern U.S. could see higher levels of smog, more frequent days of unhealthy air and a greater risk of respiratory problems as average temperatures continue to rise, according to a study released today by the Natural Resources Defense Council (NRDC).

The analysis indicates that, by the middle of this century, 50 U.S. cities could see twice as many "red alert" unhealthy air days as today, as well as a 15-percent drop in the number of summer days with good air quality and an average of 5 1/2 more days in which ozone levels exceed the current eight-hour health standard set by the U.S. Environmental Protection Agency (EPA).

"The air in many of our nation's cities is already unhealthy," said Dan Lashof, the science director for NRDC's Climate Center. "Hotter weather means more bad air days for millions of Americans. People with asthma are especially at risk, but everyone is adversely harmed by breathing unhealthy air. This research provides another compelling reason to establish enforceable limits on pollution."

The study was prepared by researchers at Yale, Johns Hopkins and Columbia universities, the State University of New York at Albany and the University of Wisconsin-Madison. The science and medical experts developed the analysis using climate, ozone and public health data from the 2007 journal Climatic Change.

Their report, "Heat Advisory: How Global Warming Causes More Bad Air Days," predicts that higher average temperatures across the U.S. will generate higher levels of smog, even if the level of pollutants entering the air remains the same as today. Smog is formed when auto and industrial emissions react with sunlight and heat. Severe instances of smog have been blamed for hundreds of deaths on several occasions in the U.S. alone.

The researchers focused on data for 10 cities in the eastern and southern U.S. with different populations, sizes and geographies: Asheville, North Carolina; Cleveland, Ohio; Columbus, Ohio; Greenville, South Carolina; Memphis, Tennessee; Philadelphia, Pennsylvania; Raleigh, North Carolina; Virginia Beach, Virginia; Washington, D.C.; and Wilmington, North Carolina. They found, among other results, that Washington, D.C. could expect a 24-percent drop in clean air days during the summers by mid-century.

The study also points to the need for the EPA to reduce its acceptable level for ozone pollution from 84 parts per billion to between 60 parts per billion and 70 parts per billion, something that had been recommended earlier by a panel of science advisers.

"EPA should reduce the ozone standard to within the range recommended by its science advisers," said Kristen Welker-Hood of Physicians for Social Responsibility's Environment and Health Programs. "A standard at the lower end of that range will save more lives. During warmer months high ozone levels already create breathing problems for children, elderly and those with respiratory diseases. We know that global warming will lead to higher temperatures, especially in urban areas, and as this study shows, we can expect more and more suffering related to unhealthy air the longer we wait to address global warming."

Natural Resources Defense Council, "New Study: Smog Poses Greater Health Risk Because of Global Warming." URL: (http://www.nrdc.org/media/2007/070913.asp)