High court gives EPA a partial victory.

In a major setback for polluters, the U.S. Supreme Court ruled last week that the Environmental Protection Agency can implement tougher controls on tiny airborne particulates that can get deep inside people's lungs. The court also temporarily quashed EPA's ability to strengthen its limits on smog's ozone.

Four years ago, EPA proposed substantially tighter limits on out-door concentrations of both pollutants (SN: 12/21 & 28/96, p. 410). However, before the agency could implement the new rules, it was sued by several industries that would be affected by them.

The lawsuit raised three major issues. First, it argued that EPA should have weighed the impact of the rules' high implementation costs before determining that tougher pollution controls are justified. The high court countered that there is ample evidence that Congress had intended the Clean Air Act to prohibit EPA from considering such costs when setting pollution limits. In implementing the rules, the court said, states can consider costs when choosing specific pollution-control strategies.

The second issue pivoted on the Clean Air Act's charges to "protect the public health" and offer "an adequate margin of safety." The parties suing EPA argued that these terms lack the clarity needed to determine how much protection is too little or too much. The Court rejected this, arguing that the act directed the agency to use data from expert reviews, so EPA's leeway in setting limits is broad but not arbitrary.

Finally, the lawsuit noted that the proposed changes in ozone rules were confusing, if not illegal. Deadlines for these more stringent limits conflicted with congressionally mandated dead-lines for the existing ozone standard. The Supreme Court agreed and also argued that EPN's interpretation of how to resolve this knot was flawed. It therefore instructed the agency to hold up any implementation of the new ozone standard until it could rectify the apparent incongruities.

--J.R.