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New Actions on Acid Rain, Ozone, and Particulate Matter

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The federal government’s clean air initiative, Turning the Corner: An Action Plan to Reduce Greenhouse Gases and Air Pollution, includes a regulatory framework for air emissions that sets out proposed mandatory and enforceable reductions in emissions of air pollutants and greenhouse gases from industrial sectors, as well as regulatory and other action plans for transportation and consumer and commercial products. In addition to delivering measurable overall health and environmental benefits, the expected reductions in SO2 and NOX emissions from industry and transportation will lead to reductions in acid deposition and improvements in visibility.


Due to recent research on health effects from ozone, EPA established new, tighter primary and secondary National Ambient Air Quality Standards (NAAQS) for ozone. In October 2006, EPA completed a required five-year review of the PM standards, maintained the existing annual PM2.5 standard, and established a more protective 24-hour standard. EPA also retained the existing 24-hour PM10 standard but revoked the annual PM10 standard because of a lack of evidence linking health problems to long-term exposure to coarse particle pollution.

Particulate Matter

PM includes both solid particles and liquid droplets found in the air. Many manmade and natural sources emit PM directly or other pollutants that react in the atmosphere to form PM. PM comes in a range of sizes and is associated with numerous health effects. Particles less than 10 micrometers in diameter (PM10)—especially those less than 2.5 micrometers in diameter (PM2.5)—pose the greatest health risk because they can be inhaled and impact both the respiratory and cardiac systems. Sulfates (SO4) and nitrates (NO3) formed from SO2 and NOX are significant components of PM2.5. PM is also a major contributor to regional haze, which reduces visibility.

New England Governors (NEG) and Eastern Canadian Premiers (ECP)

The 31st Conference of the NEG/ECP was held in June 2007. During this meeting, the governors and premiers established a standing committee to draft a regional Transportation and Air Quality Action Plan. More information on this work and other work of the NEG/ECP can be found at <www.cap-cpma.ca/>.

PM Annex Negotiations

Both countries are committed to negotiating the addition of a PM Annex to the United States–Canada AQA while actively developing and implementing emission reduction programs to reduce fine particle concentrations. The United States and Canada have held two negotiating sessions on a PM Annex under the United States–Canada AQA: one in November 2007 and one in May 2008. Substantial progress was made during the most recent session, and intersessional work is continuing.

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