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