Opinion ID: 187302
Heading Depth: 2
Heading Rank: 2

Heading: Morbidity Among Vulnerable Subpopulations

Text: The state petitioners believe the EPA unreasonably concluded morbidity studies did not provide a basis for setting a primary annual standard for PM2.5 below 15 ¢g/m3. First, they argue the EPA arbitrarily refused to rely upon a study finding an association between irreversible lung damage in children and long-term exposure to PM2.5 at levels below 15 ¢g/m3. See W. James Gauderman et al., Association Between Air Pollution and Lung Function Growth in Southern California Children, 162 AM. J. RESPIRATORY & CRITICAL CARE MED. 1383 (2000). The staff thought the Gauderman Study, if given appreciable weight, indicated an annual standard of 13 ¢g/m3. See STAFF PAPER § 5.3.4.1, at 5-22-23. Although the CASAC did not advert to the Gauderman Study, it recommended a level of 13 to 14 ¢g/m3 based upon the risk assessment and the short-term studies. See CASAC Mar. 21 Letter at 1. The EPA acknowledged the Gauderman Study presented important new findings but decided not to rely upon it because it was the only study measuring decreased growth in lung function over time and it focused solely upon children in one location. 2006 Final Rule, 71 Fed. Reg. at 61,172/2-3. The state petitioners complain that the EPA's rejection of the Gauderman Study was based upon the faulty premise that further study ... would be needed to increase confidence in the reported associations because no other study in the record was consistent with the results of the Gauderman Study. Id. at 61,172/3. According to the state petitioners, the findings of the Gauderman Study are supported by Mark Raizenne et al., Health Effects of Acid Aerosols on North American Children: Pulmonary Function, 104 ENVTL. HEALTH PERSP. 506 (1996) (24-Cities Study). The EPA disagreed: the 24-Cities Study measured decreased lung function at a single point in time while the Gauderman Study found decreased growth in lung function over time. 2006 Final Rule, 71 Fed.Reg. at 61,172/3. We believe the EPA's approach to the Gauderman and 24-Cities studies was unreasonable in light of the agency's obligation to explain how the annual standard it set would protect not only average healthy individuals, but also `sensitive citizens.' Am. Lung Ass'n v. EPA, 134 F.3d 388, 389 (D.C.Cir.1998). As the American Lung Association argued during the rulemaking and the EPA agreedwith each breath a child aspirates more pollution relative to its body weight than does an adult. See American Lung Association (ALA) et al., Comments, 2006 Rulemaking, Pub. Dkt. No. OAR-2001-0017-1890.1, at 17 (filed Apr. 17, 2006); 2006 Proposed Rule, 71 Fed.Reg. at 2637/1 (Several factors may make children susceptible to PM-related effects, including the greater ventilation rate per kilogram body weight in children). We therefore doubt whether the studies of adult mortality upon which the EPA relied provide the necessary confidence concerning the risk of morbidity in children. We doubt the reasonableness of the EPA's analysis for a second reason: the agency imputed undue significance to one difference, despite many similarities, between the Gauderman Study, which focused upon the growth over time of lung function in children, and the 24-Cities Study, which focused upon the level of lung function of children at a particular time. Both studies found an association between exposure to PM2.5 at levels below 15 ¢g/m3 and impairment of lung function in children, although the association in the 24-Cities Study was not statistically significant below 15 ¢g/m3, 2006 Final Rule, 71 Fed.Reg. at 61,172/3. Indeed, the 24-Cities Study predicted the children it examined might continue on [a] track [of reduced] ... growth of their lung function, as suggested by previous studies, Raizenne et al. at 513, which was consistent with the findings of the later Gauderman Study, see Gauderman et al. at 1388. The EPA also relied upon its 1997 conclusion that the 24-Cities Study does not show a statistically significant association between health effects and annual average concentrations of PM2.5 below 15 ¢g/m3. See 2006 Final Rule, 71 Fed.Reg. at 61,172/3. Viewed in isolation, of course, the studies are far from conclusive. Viewed together in the context of the studies the EPA considered when deciding whether to revise the standard for PM2.5, however, the conclusion reached after comprehensive scientific review by the EPA's National Center for Environmental Assessment in the Criteria Document seems the only reasonable one: the findings of the Gauderman and 24-Cities studies are related and together indicate a significant public health risk. See CRITERIA DOCUMENT § 8.4.6.4, at 8-314; cf. 2006 Final Rule, 71 Fed.Reg. at 61,154/1 ([T]he Criteria Document found that new studies of a cohort of children in Southern California have built upon earlier limited evidence to provide fairly strong evidence that long-term exposure to fine particles is associated with development of chronic respiratory disease and reduced lung function growth). On this record, therefore, it appears the EPA too hastily discounted the Gauderman and 24-Cities studies as lacking in significance. See Am. Radio Relay League, Inc. v. FCC, 524 F.3d 227, 241 (D.C.Cir.2008) (agency's inadequate explanation for dismissing empirical studies rendered decision arbitrary and capricious); cf. ATA I, 175 F.3d at 1052-53 (EPA arbitrarily and capriciously placed upon some studies higher information threshold than it placed upon others). Second, the state petitioners argue the EPA should have explained how an annual standard of 15 ¢g/m3 would provide an adequate margin of safety for vulnerable subpopulations, such as children, the elderly, or those with conditions that expose them to greater risk from fine particles. The EPA said there was insufficient evidence that vulnerable subpopulations will be exposed to adverse health effects at annual levels of PM lower than 15 ¢g/m3. See 2006 Final Rule, 71 Fed.Reg. at 61,173/1. Having concluded the EPA failed adequately to consider the Gauderman and 24-Cities studies, however, we are constrained to agree with the state petitioners that the EPA was unreasonably confident that, even though it relied solely upon long-term mortality studies, the revised standard would provide an adequate margin of safety with respect to morbidity among children. Notably absent from the final rule, moreover, is any indication of how the standard will adequately reduce risks to the elderly or to those with certain heart or lung diseases despite (a) the EPA's determination in its proposed rule that those subpopulations are at greater risk from exposure to fine particles and (b) the evidence in the record supporting that determination. See 2006 Proposed Rule, 71 Fed.Reg. at 2637/1; STAFF PAPER § 3.3.2, at 3-19-22 & fig.3-2 (charting risk of morbidity for persons with various diseases, but noting associations between exposure to PM2.5 and certain heart diseases and stroke are not statistically significant); CRITERIA DOCUMENT § 8.4.9, at 8-327-28 (citing studies discussing risks to older adults and children); ALA Comments at 52 (discussing risk to elderly at level of 12 ¢g/m3). We therefore grant the petition for review and remand this matter for the EPA to explain why it believes the NAAQS will provide, as required by the CAA, an adequate margin of safety against morbidity in children and other vulnerable subpopulations. See Am. Lung Ass'n, 134 F.3d at 393 (remanding because EPA had failed adequately to explain [why there is] ... no public health threat to asthmatics).