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Fall 2009 Vol. 9 Number 2

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No Borders for Air Pollutants

Take a deep breath. Now take another. Did you know that the air you are inhaling could contain pollution that traveled here all the way from Asia? Or that air particles from the United States can drift across the Atlantic Ocean to Europe?

A recent report from the National Research Council finds that air pollutants can be transported aloft across the Northern Hemisphere to continents that lie downwind. Although air quality is nearly always dominated by local or regional emissions, air pollutants from abroad are becoming a growing concern as emissions from developing countries increase and environmental protection standards tighten in industrialized nations.

“Air pollution does not stop at national borders,” said Charles Kolb, chair of the committee that wrote the report and president and chief executive officer of Aerodyne Research Inc. “It travels through the atmosphere to distant regions of our planet and can affect the health of people and ecosystems.”

Distinguishing between domestic and foreign components of air pollution and quantifying how global sources actually affect air quality and ecosystems is currently constrained by modeling and observational capabilities. Yet, some air pollution plumes observed in the U.S. can be attributed unambiguously to sources in Asia based on meteorological and chemical analyses. For example, one study found that a polluted airmass detected at Mt. Bachelor Observatory in Oregon took approximately eight days to travel from East Asia.

In the coming decades the concern over pollutants will grow, particularly as manmade emissions are expected to rise in East Asia. However, these increases could potentially be mitigated by progressively more stringent pollution control efforts and international cooperation in developing and deploying pollution control technology.

Projected climate change will also likely affect the emissions and travel of pollutants, but predicting the net impacts of these potential changes is extremely difficult with present knowledge.

To improve understanding of long-range transport of pollution, the report recommends a variety of research initiatives, such as “fingerprinting” techniques to better identify source-specific pollutant characteristics, atmospheric modeling, ground-based and remote sensing observations, and focused field studies. — Jennifer Walsh

 Global Sources of Local Pollution: An Assessment of Long-Range Transport of Key Air Pollutants to and from the United States. Committee on the Significance of International Transport of Air Pollution, Board on Atmospheric Sciences and Climate, Division on Earth and Life Studies (2009, approx. 250 pp.; ISBN 0-309-0-30914401-9; available from the National Academies Press, tel. 1-800-624-6242; $35.00 plus $5.00 shipping for single copies).

The committee was chaired by Charles Kolb, president and chief executive officer of Aerodyne Research Inc., Billerica, Mass. The study was funded by the Environmental Protection Agency, NASA, National Oceanic and Atmospheric Administration, and National Science Foundation.

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Copyright 2009 by the National Academy of Sciences