## Facts

- EPA, acting under Clean Air Act (CAA) §§ 108–109, revised the primary and secondary National Ambient Air Quality Standards (NAAQS) for lead in a 2008 final rule.
- The rule lowered the lead NAAQS from 1.5 µg/m³ (calendar-quarter average) to 0.15 µg/m³ and changed compliance from a calendar-quarter average to a rolling three-month average.
- EPA’s rulemaking relied on a large scientific record (including thousands of studies) indicating significant neurocognitive harms to children at low blood-lead levels and no recognized safe blood-lead level for children.
- EPA’s risk assessment emphasized protecting sensitive populations, especially young children, and used population-level IQ decrement as a regulatory endpoint linked to lead exposure.
- Petitioners (lead-emitting sources, including battery recyclers and lead producers) sought judicial review, contending the revised level and averaging time were arbitrary and capricious and inadequately supported by the record.

## Issues

1. Whether EPA acted arbitrarily or capriciously in substantially lowering the lead NAAQS to protect children from IQ loss and related neurocognitive effects.
2. Whether EPA reasonably selected and interpreted the scientific studies and modeling used to relate ambient lead to blood-lead levels and IQ decrements.
3. Whether EPA acted arbitrarily or capriciously in adopting a rolling three-month averaging time rather than an annual (or other) averaging period.
4. Whether EPA provided a reasoned explanation, consistent with CAA §§ 108–109 and the APA, for the form and stringency of the revised lead NAAQS.

## Decision

- The D.C. Circuit denied the petitions for review and upheld EPA’s 2008 revisions to the lead NAAQS.
- The court held EPA’s actions were supported by the rulemaking record and reflected reasoned decision-making rather than arbitrary or capricious action.
- The court sustained EPA’s focus on protecting sensitive populations (children) and its use of IQ decrement as a health endpoint.
- The court sustained EPA’s choice of studies and models as within EPA’s scientific discretion.
- The court sustained the rolling three-month averaging period as reasonably connected to evidence about health risks from shorter-term lead exposure.

## Legal Principles

- Under CAA §§ 108–109, EPA must set NAAQS at levels requisite to protect public health with an adequate margin of safety and may prioritize protection of sensitive populations.
- Judicial review of NAAQS under the APA’s arbitrary-and-capricious standard is deferential to EPA’s scientific and technical judgments when EPA evaluates the evidence, considers relevant factors, and explains its choices.
- EPA may tighten health-based standards in response to updated scientific evidence, including evidence of harmful effects at low exposure levels and uncertainty about a safe threshold.
- EPA may select reasonable averaging times and regulatory forms when the choice is explained and supported by the health evidence and exposure-risk relationships in the record.

## Conclusion

The D.C. Circuit upheld EPA’s 2008 lead NAAQS revisions, concluding EPA reasonably relied on the scientific record to protect children from neurocognitive harms, reasonably chose supporting studies and models, and adequately justified adopting a more stringent level and a rolling three-month averaging period under the CAA and APA.


Coalition of Battery Recyclers Ass'n v. EPA, 604 F.3d 613 (D.C. Cir. 2010)