EPA Accelerates Review of Air Quality Standards for Fine Particulate Matter
In October 2009, the U.S. Environmental Protection Agency ("EPA") announced an accelerated schedule for issuing new National Ambient Air Quality Standards ("NAAQS") for fine particulate matter, or "PM2.5." Specifically, EPA intends to propose new NAAQS for PM2.5 by July 2010 and implement a final rule by April 2011. Particulate matter is a mixture of microscopic solids and liquid droplets suspended in the air. Particulate matter is produced through all types of combustion activities and certain industrial processes. According to EPA, exposure to particulate matter can cause a variety of serious health problems, including heart and lung diseases, decreased lung function, asthma attacks, and even premature death. Fine particles are believed to pose the greatest health risks, because they are small enough to lodge deeply in the lungs.
In October 2006, EPA revised the NAAQS for PM2.5 (the "2006 PM2.5 NAAQS"). The 2006 PM2.5 NAAQS tightened the primary and secondary daily standards from 65 micrograms per cubic meter ("µg/m3") to 35 µg/m3, but retained the primary and secondary annual standards of 15 µg/m3. Several groups, including environmental groups and states and state agencies, among others, filed petitions for review in the U.S. Circuit Court of Appeals for the District of Columbia Circuit, challenging the 2006 PM2.5 NAAQS. On February 24, 2009, finding that EPA failed to adequately explain why an annual level of 15 µg/m3 is required to protect the public health, the Court remanded the primary annual PM2.5 standard to EPA for reconsideration. The Court also remanded the secondary PM2.5 standards, determining that EPA unreasonably concluded that the NAAQS are adequate to protect the public welfare from adverse effects on visibility.