EPA Must Rethink Standard For Particles

The Environmental Protection Agency has an opportunity to make the national air quality standard for fine particulate matter more protective because of a federal appeals court ruling on Feb. 24.

In its decision, the U.S. Circuit Court for the District of Columbia instructed EPA to reconsider the Bush Administration's 2006 decision to maintain, and not tighten, the 1997 standard for fine particulates. That annual standard is 15 µg of fine particulate matter per cubic meter of air.

Exposure to fine particulate matter, defined as particles with a diameter of 2.5 µm or less, is linked to cardiovascular problems and premature death. Sources of fine particulates include power plants, industrial processes, vehicle exhaust, and forest fires.

EPA set the 15 µg/m³ standard in 1997. As required by the Clean Air Act, the Bush Administration reviewed that standard in 2006. During that review, EPA's Clean Air Scientific Advisory Committee recommended lowering the fine particulate standard to between 13 and 14 µg/m³ to protect health, on the basis of health studies conducted since 1997.

In September 2006, EPA's then-Administrator Stephen L. Johnson, a Bush appointee, chose not to heed the recommendation of the science advisers and decided to maintain the 15 µg/m3 standard.

The court faulted EPA for not describing how the 15 µg/m³ standard would be protective of health. "EPA failed adequately to explain why, in view of the risks posed by short-term exposures and the evidence of morbidity resulting from long-term exposures, its annual standard is sufficient to protect the public health," the court said.

The court returned the standard to the agency for reconsideration, providing the Obama Administration with an opportunity to tighten it.

Environmental activists and 16 states challenged the 15 µg/m³ standard in court, saying it was not protective enough.