National Association of Manufacturers v. Environmental Protection Agency

In 2013, the Environmental Protection Agency (EPA) (defendant) established stricter National Ambient Air Quality Standards (NAAQS) for fine particulate matter. This rule was enacted after an EPA notice of proposed rulemaking requesting comments on all issues related to the EPA’s proposal to lower the particulate-matter NAAQS. Under the new rule, the EPA revised the existing acceptable level of particulate-matter emissions down from the previously acceptable level established by the EPA in 2007 after concluding that the existing standards were not sufficiently protective of public health. The EPA based this decision on several epidemiological studies that showed statistically significant associations between adverse health and levels of particulate matter that were below the 2007 particulate-matter NAAQS. The new standard was slightly lower than the lowest concentration reported to cause health effects in epidemiological studies. The National Association of Manufacturers (the manufacturers) (plaintiff) petitioned the court to review the EPA’s new rule, arguing that the EPA’s revisions to the NAAQS for fine particulate matter were unreasonable. The manufacturers argued that the EPA failed to request comments on whether to revise the particulate-matter NAAQS and also did not address comments submitted to the EPA by the manufacturers that cited studies supporting the maintenance of the existing standards. The manufacturers also claim that the EPA afforded disproportionate weight to those studies that found associations between particulate-matter exposure and adverse health effects.