## Facts

- EPA listed lead as a criteria pollutant under Clean Air Act (CAA) §§ 108–109 and issued primary and secondary National Ambient Air Quality Standards (NAAQS) for lead.
- In 1978, EPA set identical primary and secondary lead NAAQS at 1.5 micrograms per cubic meter of air, averaged over a calendar quarter.
- EPA relied on a scientific criteria document and public comments, concluding lead exposure can harm hematologic and neurological systems and that young children and pregnant women are especially vulnerable.
- Lead producers and a major lead producer petitioned for review, arguing EPA lacked statutory authority to set the standard without considering feasibility and that the standard was scientifically and procedurally defective.
- Petitioners also challenged EPA’s use of total suspended particulate lead (including insoluble and non-respirable particles) as the indicator for the standard.

## Issues

1. Whether CAA §§ 108–109 require EPA to consider economic and technological feasibility when setting primary (and related) NAAQS for lead.
2. Whether EPA’s lead NAAQS were arbitrary or capricious because they relied on “subclinical” effects and addressed scientific uncertainty through an “adequate margin of safety.”
3. Whether EPA’s selection of the pollutant indicator (including insoluble and non-respirable particles) and its rulemaking procedures were legally sufficient.

## Decision

- The D.C. Circuit denied the petitions for review and upheld EPA’s lead NAAQS in full.
- The court held EPA did not exceed statutory authority by setting the standards without considering compliance costs or technological feasibility.
- The court held the standards were not arbitrary or capricious and were supported by the administrative record.
- The court rejected challenges to EPA’s indicator choice and rejected the asserted procedural deficiencies.

## Legal Principles

- Primary NAAQS under CAA § 109(b)(1) must be set at levels “requisite to protect the public health” with “an adequate margin of safety,” and this directive does not permit consideration of economic or technological feasibility.
- EPA may regulate to protect sensitive populations and may treat statistically supported “subclinical” effects as adverse health effects when determining what is “requisite” to protect public health.
- The “adequate margin of safety” authorizes EPA to make protective judgments in the face of scientific uncertainty; the Act does not require proof of clinical disease before regulation.
- Under arbitrary-and-capricious review, courts generally defer to EPA’s reasonable resolution of competing scientific evidence and expert opinions when the agency explains its choice and grounds it in the record.
- EPA has latitude to choose a workable indicator and form of a NAAQS, so long as the selection is rational and consistent with the statute.
- Notice-and-comment rulemaking is sufficient where EPA provides an opportunity to comment, responds to significant comments, and builds a record supporting its conclusions.

## Conclusion

The court sustained EPA’s lead NAAQS, holding that primary ambient air standards are health-based and exclude cost considerations, and that EPA may use reasoned scientific judgment—accounting for uncertainty and protecting vulnerable groups—so long as its decisions are adequately explained and supported by the record.


Lead Indus. Ass’n, Inc. v. EPA, 647 F.2d 1130 (D.C. Cir. 1980)