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Court of Appeals for the D.C. Circuit • 1999

American Lung Association v. Environmental Protection Agency

134 F.3d 388

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Takeaway

In short, this case holds that EPA may exercise scientific judgment in setting NAAQS, but it must clearly explain why documented, repeated harms to thousands of sensitive individuals do not constitute a public-health problem requiring national protection.

Background

The Clean Air Act requires EPA to set primary national ambient air quality standards (NAAQS) that, with an adequate margin of safety, are requisite to protect public health. In setting those standards, EPA must consider sensitive populations, including people with asthma, and may not base the health standard on cost or technological feasibility.

Sulfur dioxide (SO2), produced largely by fossil-fuel combustion, can cause bronchoconstriction in asthmatics. The dispute concerned short, high-level SO2 bursts of at least 0.50 parts per million lasting five minutes or more. Clinical evidence showed that, when mildly or moderately asthmatic people exercised and breathed heavily while exposed to 0.60 ppm of SO2 for five minutes, at least 25 percent experienced lung-function effects beyond ordinary daily variation. Those effects could disrupt activities, require bronchodilator medication, or lead to medical attention.

After years of petitions, litigation compelling agency action, notice, and comment, EPA declined to revise its existing annual and 24-hour primary SO2 standards or add a five-minute standard. EPA acknowledged estimates of 180,000 to 395,000 annual exposure events, affecting as many as 166,000 asthmatics, but described the episodes as localized, infrequent, and site-specific. It concluded that the bursts did not present a broad public-health problem requiring a national standard, while proposing to encourage state-level responses.

The environmental petitioners sought direct judicial review of EPA's final NAAQS decision under the Clean Air Act. There was no lower-court merits decision; the D.C. Circuit reviewed the agency action and remanded it to EPA for further explanation.

Issues

Issue #1

Whether EPA adequately explained its conclusion that short-term high-level SO2 bursts did not create a public-health problem requiring a new national ambient air quality standard.

Holding

No. EPA's explanation was insufficient for arbitrary-and-capricious review, so the court remanded the decision to the agency for further elucidation.

Reasoning

The court accepted, under the deferential review owed to EPA's scientific expertise, the agency's treatment of the exposure studies. On EPA's own reading of the record, thousands of asthmatics could experience atypical reactions to repeated short-term SO2 bursts each year. That factual premise made an explanation of EPA's ultimate public-health judgment especially necessary.

EPA had found that repeated episodes of substantial bronchoconstriction were significant from a public-health standpoint. Yet it never explained why the estimated number of repeated exposures—potentially affecting as many as 41,500 asthmatics under the agency's own figures—was too small or too infrequent to qualify as a public-health problem under the Clean Air Act.

Calling the emissions localized, site-specific, and infrequent did not bridge the gap in EPA's reasoning. Pollution can be local and still endanger public health, and the record identified at least six communities with repeated five-minute peaks above 0.60 ppm. EPA did not explain why those locations, or other places with repeated exposure, amounted only to a local concern outside the proper scope of a NAAQS.

Reasoned decision-making is a prerequisite to judicial deference. Because EPA did not articulate a standard for deciding how many affected people, how many repeated exposures, or what degree of symptom disruption constitutes a public-health problem, the court could not determine whether the agency had acted lawfully under the Clean Air Act's requirement to protect public health with an adequate margin of safety.

Issue #2

Whether EPA was required to decide whether a single asthmatic reaction to a short-term SO2 burst was an adverse health effect, and whether the Clean Air Act permits EPA to decline national protection from documented adverse effects.

Holding

The court did not decide either question because EPA's unexplained public-health determination independently required remand.

Reasoning

Petitioners argued that EPA's findings effectively established adverse health effects and therefore triggered a duty to promulgate a more protective standard. EPA responded that it had deliberately left unresolved whether a single reaction—such as activity disruption, medication use, or possible medical attention—was an adverse health effect rather than an ordinary and reversible asthma symptom.

The court held that resolving this dispute was unnecessary at that stage. Even accepting EPA's decision to focus on repeated occurrences rather than individual episodes, the agency still had to explain why repeated effects that it regarded as significant did not amount to a public-health problem.

The court also declined to resolve the broader statutory question whether EPA may refuse to establish a margin of safety for an identifiable sensitive group facing known adverse effects. Prior precedent establishes EPA's broad discretion to err on the side of caution amid scientific uncertainty, but it did not definitively answer the converse question. The court left that issue for a future case or a better-explained agency decision.