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Media Alerts - Mississippi v. EPA
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July 23, 2013
  Mississippi v. EPA
Headline: D.C. Circuit Upholds Reduced Ozone Emissions Standards

Area of Law: Environmental law; Administrative Law

Issue(s) Presented: Whether EPA adequately considered reliable scientific evidence in deciding to reduce ozone emissions standards.

Brief Summary: Two groups, one a coalition of industry associations and the state of Mississippi, and one a coalition of environmental groups and cities, challenged recent changes to the National Ambient Air Quality Standards (NAAQS) for ozone, a main component of smog, in the Court of Appeals for the District of Columbia Circuit. The Clean Air Act directs EPA to establish and periodically review and revise primary and secondary emissions standards for pollutants that "cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare." 42 U.S.C. § 7408(a)(1)(A). Both primary and secondary standards are statutorily mandated to limit pollutants to levels "requisite to protect the public health [or welfare]" with an "adequate margin of safety" and are committed to the "judgment of the Administrator [of the EPA]." 42 U.S.C. §7409(b). Current ozone standards were implemented in 1997, setting 8-hour primary and secondary standards at 0.08 parts per million (ppm). The revisions under consideration were issued in 2008 and lowered both standards to 0.075 ppm. In reaching its conclusion that the old standard was not sufficient to meet the statutory requirements, EPA exhaustively examined available scientific data on the association of exposure to ambient ozone and a broad range of "health endpoints," emphasizing new clinical studies and epidemiological evidence demonstrating health effects at exposure levels below 0.08.

The industry petitioners challenged the threshold decision to revise the primary NAAQS standards, arguing that several aspects of that decision were arbitrary, including EPA's reliance on unsupported findings that more stringent standards would provide increased public health and welfare protections, EPA's failure to compare the risk assessment completed in support of the revisions with the one supporting the previous standard, and EPA's decision to base the revisions on "inadequate and distorted" science. The environmental petitioners challenged the revisions as not stringent enough, claiming that EPA failed to rationally consider scientific evidence of adverse health effects from lower ozone levels, failed to calculate an adequate margin of safety in setting permissible levels, and failed to adequately defend its decision to depart from Clean Air Scientific Advisory Committee recommendations, which would have resulted in standards under 0.07 ppm.

Emphasizing that the science regarding the health effects of ozone and what constitutes a safe level of exposure is far from settled, and that the court's role is not to "referee battles among experts ... only to evaluate the rationality of EPA's decision," the D.C. Circuit rejected most of the challenges to the revised standards, finding that EPA had considered all the evidence available to it and had adequately explained its scientific and policy judgments in weighing that evidence and determining appropriate emissions standards. However, the court upheld the environmental petitioners' challenge to the secondary standard, which protects against the harmful effects of ozone on vegetation and indirect effects on other ecosystems. Relying on American Farm Bureau Fed'n v. EPA, 559 F.3d 512 (D.C. Cir. 2009), the court found that EPA had not adequately demonstrated that the new secondary standard was sufficient to protect public welfare. It remanded that portion of the rule for further consideration.

For the full text of the opinion, please visit

    Posted By: Ripple Weistling @ 07/23/2013 03:47 PM     DC Circuit  

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