Air Quality: EPA's 2006 Changes to the Particulate Matter (PM) Standard [Updated May 14, 2007] [open pdf - 408KB]
"On October 17, 2006, the EPA published its final revisions to the National Ambient Air Quality Standards (NAAQS) for particulate matter (particulates, or PM). The EPA reviewed more than 2,000 scientific studies and found that the evidence continued to support associations between exposure to particulates in ambient air and numerous significant health problems, including aggravated asthma, chronic bronchitis, reduced lung function, heart attacks, and premature death in people with heart or lung disease. Based on several analytical approaches, the EPA estimated that compliance with the new NAAQS will prevent 1,200 to 13,000 premature deaths annually, as well as substantial numbers of hospital admissions and missed work or school days due to illness. Although a tightening of the standards, the new particulates NAAQS are not as stringent as recommended by EPA staff or the independent scientific advisory committee (Clean Air Scientific Advisory Committee, or CASAC) mandated under the Clean Air Act. The new particulates NAAQS strengthen the pre-existing (1997) standard for 'fine' particulate matter 2.5 micrometers or less in diameter (PM2.5) by lowering the allowable daily concentration of PM2.5 in the air. The new daily standard averaged over 24-hour periods is reduced from 65 micrograms per cubic meter (µg/m3) to 35 µg/m3. However, the annual PM2.5 standard, which is set in addition to the daily standard to address human health effects from chronic exposures to the pollutants, is unchanged from the 1997 standard of 15 µg/m3, although the CASAC had recommended a tighter annual standard in the range of 13 to 14 µg/m3."
CRS Report for Congress, RL33254
National Agricultural Law Center http://www.nationalaglawcenter.org/crs/