EPA Opens Assault On PM

Posted on December 21, 2005

The U.S. Environmental Protection Agency’s (EPA) expected assault on particulate matter (PM) has started with EPA proposing revisions to its national air quality standards for fine particle pollution and from some coarse particles.

The proposed revisions will address two categories of particulate matter: fine particles which are particles 2.5 micrometers in diameter and smaller; and "inhalable coarse" particles, which are particles between 2.5 and 10 micrometers (PM10-2.5). EPA has had national air quality standards for fine particles since 1997 and for coarse particles 10 micrometers and smaller (PM10) since 1987. The proposed revisions include the significant strengthening -- by nearly 50 percent -- of EPA's standards to protect the public from short-term exposure to high levels of fine particles. For fine particles, EPA is also taking comment on a range of annual and 24-hour standards, including strengthening these standards as well as retaining the standards at their present levels.

In addition, EPA is proposing a standard for reducing inhalable coarse particles, or PM10-2.5. For these particles, EPA is proposing a 24-hour standard of 70 micrograms per cubic meter. The standard would apply to airborne mixes of coarse particles that come from sources such as high-density traffic on paved roads and industry. The proposed standard would not apply to mixes of coarse particles that do not pose much risk to public health, such as windblown dust and soils and agricultural and mining sources.

The Bush Administration has proposed Clear Skies legislation and issued a number of rules that will make significant strides toward reducing particles regionally and nationally -- the Clean Air Interstate Rule to reduce emissions from power plants in the eastern United States; the Clean Diesel Program to reduce emissions from highway, non-road and stationary diesel engines across the country; and the Clean Air Visibility Rule to reduce emissions near national parks.

In a separate but related action, EPA is proposing amendments to its national air quality monitoring requirements, including those for monitoring particle pollution. The changes will help EPA, states and local air quality agencies in their efforts to improve public health protection and inform the public about air quality in their communities, and they will allow air quality regulators to take advantage of improvements in monitoring technology.

EPA is seeking comments on a number of alternative levels for the PM standards, including retaining the current standards. The agency will take public comment for 90 days following publication of the proposal in the Federal Register and will hold three public hearings.

For additional information see: