Between 1999 and 2003, levels of airborne particulate matter decreased in the United States: 10% for fine particles less than 2,5 micron diameter (PM2,5) - the most hazardous to health - and 7 % for those under 10 microns (PM10).
On 25 years, these declines even reach the 30%, according to estimates by the Environmental Protection Agency (EPA), which publishes this week an inventory of particulate pollution across the territory (http://www.epa.gov/airtrends/).
But if the global trend is positive, the local situations appear very variable. The Los Angeles area, for example, in California, remains the most polluted in the country despite significant progress. While in the Northeast, PM2,5 levels increased due to automotive and industrial emissions. According to the EPA, improvements in the Southeast and Midwest would be largely the result of the Acid Rain program, which reduced 33% from 1990 to 2003's sulfur dioxide emissions from power plants.
The agency also hopes that the application of the Clean Air Nonroad Diesel Rule, specifying fine particle standards, and the finalization of the Clean Air Interstate Rule will strengthen the results achieved so far. The environmental movements, while welcoming the government report, denounce repeated delays in adopting stricter rules, particularly in the energy sector.
LAT 15 / 12 / 04 (US registers drop in levels of fine-particle pollution) http://www.latimes.com/