Air Quality Standards for PM | Power Plants Are Reducing Emissions | Better Science Needed | Resources
Very small, or fine, particles are released into the air around us—or are created—by emissions from many natural and manmade sources, including power plants. There are hundreds of types and sources of fine particles. While electric utilities remove more than 99 percent of direct fine particle emissions produced by their power plants, reactions in the atmosphere involving emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) generate sulfates and nitrates, two of the many types of fine particulate matter.
Air Quality Standards for PM
In 1997, the U.S. Environmental Protection Agency (EPA) revised the National Ambient Air Quality Standards (NAAQS) for particles to create new fine particle (PM2.5) standards—15 micrograms per cubic meter for an annual average and 65 micrograms per cubic meter for a 24-hour average. Even as states are now preparing implementation plans to meet the 1997 standards (with deadlines to attain the standards by 2010), EPA recently revised the daily standard again.
In September 2006, EPA tightened the daily standard from 65 to 35 micrograms per cubic meter; however, EPA did not find compelling evidence to support a change to the annual standard of 15 micrograms per cubic meter. Existing air quality improvement programs are expected to bring most of the country into compliance with the 1997 standards by 2010. In December 2008 EPA told Governors in 25 states that the 2006 standard was not met in one or more localities.
Power plants are reducing emissions.
The U.S. electric power sector has reduced air emissions substantially under existing programs. The industry has cut sulfur dioxide (SO2) emissions by 48 percent and nitrogen oxides (NOX) emissions by 54% between 1980 and 2007. The industry will achieve much greater reductions over the next decade due to EPA and state regulations like EPA's Clean Air Visibility Rule, the tightened 2006 particulate matter standard, the tightened 2008 ozone standard and EPA's Clean Air Interstate Rule or whatever replaces it. The power sector also has cut emissions of mercury by about 40 percent through efforts to reduce other pollutants. The electric power industry has achieved these reductions despite enormous increases in electricity generation (75% since 1980).
Better science is needed to set appropriate PM standards.
Imposing stricter regulations for fine particulate matter will not necessarily produce additional health benefits beyond those achieved through the current standards, but will further exacerbate energy prices and prove burdensome to local economies. In fact, EPA’s September 2006 rule is estimated to have an annual price tag of tens of billions of dollars. Even if it is assumed that current concentrations of fine particulate matter in the ambient air contribute to adverse health effects, it has not been established that emissions from power plants generate the particles of concern. EPA’s own Office of Inspector General and the National Academy of Sciences, among others, have found that more research is needed to determine the specific types of particulate matter responsible for health concerns so that EPA can set meaningful standards and implement air quality programs with tangible benefits.
See EPA's Particulate Matter Web Site