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International Cooperation

Transboundary Air Pollution

Although most air pollution problems are caused by local or regional sources of emissions, air pollution does not stop at national borders.  Transboundary flows of pollutants occur between the United States and our closest neighbors, Mexico and Canada, as well as between North America, other continents, and sources in the global commons such as international shipping and aviation. Some air pollutants are known to circulate globally and deposit on land and water bodies far from their sources.

EPA is engaged in a variety of efforts to better understand the impact of air pollution sources outside the United States on health and environmental quality in the United States, and to enable and motivate the mitigation of these sources in other countries.

Addressing Transboundary Flows in North America

EPA works closely with our colleagues in Mexico and Canada through several bilateral and multi-lateral forums, including:

Understanding Intercontinental Flows of Air Pollution

EPA has taken a leading role in focusing attention on the intercontinental transport of air pollutants:

Starting with the First International Conference on Trans-Pacific Transport of Atmospheric Contaminants in July 2000, EPA has sponsored a series of workshops and conferences to focus the attention of the research community on quantifying intercontinental flows of air pollution.

EPA, along with NOAA, NASA, and NSF, sponsored a 2009 report of the National Research Council entitled National Research Council. Global Sources of Local Pollution: An Assessment of Long-Range Transport of Key Air Pollutants to and from the United States. Washington, DC: The National Academies Press, 2009Exit

Since 2005, EPA has co-chaired, along with the European Commission, the Task Force on Hemispheric Transport of Air Pollution (TF HTAP) Exit organized under the UNECE Convention on Long-Range Transboundary Air PollutionExit

  • In 2010, TF HTAP produced the first comprehensive assessment report Exit on the intercontinental transport of air pollution across the Northern Hemisphere, covering ozone and its precursors, fine particles and their components and precursors, mercury, and persistent organic pollutants.

Fostering Global and Regional Cooperation

In addition to working with key countries bilaterally, EPA works to address global and international flows and sources of air pollution through various international forums.  This work includes: