Opinion ID: 786322
Heading Depth: 2
Heading Rank: 1

Heading: Weight of Evidence Analysis

Text: 38 Having disposed of the threshold matters, we turn to the merits. Petitioner's primary argument is that the weight of evidence analysis applied by New York and EPA contravenes the Act and the EPA's regulations. It believes this supplementary analysis fundamentally alters the results of the model to a degree that the attainment demonstration no longer can fairly be said to be based on photochemical grid modeling.
39 We discuss this challenge first with respect to the Act, and then with regard to the regulations. We begin with the language of the statute. The Clean Air Act requires that the attainment demonstration be based on photochemical grid modeling. 42 U.S.C. § 7511a(c)(2)(A). The phrase based on means to be used as a base or basis for. Webster's Third New International Dictionary 180 (1986) (definition 2). The relevant definition of basis in turn is principal component or fundamental ingredient. Id. at 182 (definition 2). In its plain meaning, based on means having as the foundation or arising from. McDaniel v. Chevron Corp., 203 F.3d 1099, 1111 (9th Cir.2000) (based on means arising from and ordinarily refers to a starting point or foundation); Mount Vernon Fire Ins. Co. v. Creative Hous. Ltd., 88 N.Y.2d 347, 645 N.Y.S.2d 433, 668 N.E.2d 404, 406 (1996) (based on essentially equivalent to arising out of); United States ex rel. Siller v. Becton Dickinson & Co., 21 F.3d 1339, 1348 (4th Cir.1994) (the ordinary meaning of based upon is derived from). The appropriate question then is whether New York's attainment demonstration, after the weight of evidence analysis, has the photochemical grid model as its foundation. 40 The statute does not articulate the role of the photochemical grid model with precision. Other courts of appeals that have examined the Act's language and the phrase based on photochemical grid modeling have found the phrase ambiguous, and we agree. See BCCA, 355 F.3d at 835; Sierra Club v. EPA, 356 F.3d 296, 305-06 (D.C.Cir.2004). The attainment demonstration need not rely solely on the grid model, and by the same token the demonstration may not abandon the model altogether. Between these two extremes is an attainment demonstration based on photochemical grid modeling; though precisely where between them is not clear. EPA has said that where the modeled results form the principal component of the analysis, an attainment demonstration obtained by adjusting those results with supplemental information is still based on the grid model. 41 The grid model is not flawless, as petitioner recognizes, and EPA concedes the model contains potential inaccuracies. It could not be otherwise when one considers the photochemical grid model is a highly complex method of predicting how chemicals will combine in the atmosphere to create ozone years in the future. A reviewing court must remember that the agency is making predictions at the frontiers of science. In examining this kind of scientific determination, as opposed to simple findings of fact, a reviewing court must generally be at its most deferential. Baltimore Gas & Elec. Co. v. Natural Res. Def. Council, Inc., 462 U.S. 87, 103, 103 S.Ct. 2246, 76 L.Ed.2d 437 (1983). 42 Although the photochemical grid analysis is the best available method of predicting ozone concentrations, EPA, based on its experience and the experience of states within its regulatory purview, has identified many inaccuracies in this form of measurement. See Guidance on Modeled Results, supra, at Table S.1; Approval and Promulgation of Implementation Plans, New York, 67 Fed.Reg. at 5175. For that reason the agency has taken appropriate steps to address those inaccuracies in the model, which steps are permissible so long as they are taken in a manner consistent with the agency's statutory mandate. 43 The record supports the EPA's conclusion that further analysis was appropriate for the New York plan. EPA found the model predicted comparable ozone levels in 2007 to levels measured in the period 1995-98 and believed this result improbable since numerous emissions reduction measures were due to be implemented between 1999 and 2007. It also found the model predicted that 87 percent of the points measured in the grid that exceeded the ozone levels in 1990 were predicted to attain the attainment standard by 2007. Given that high degree of improvement, EPA considered it anomalous that the model also predicted ozone peaks as high as 171 ppb in 2007. 44 EPA declares that even with the supplemental analysis, photochemical grid modeling results constitute the principal component of its analysis, with the additional analysis simply aiding its accounting for uncertainties in the model. 67 Fed.Reg. at 5175. The grid model results formed not only the starting point of New York's weight of evidence analysis, but they also served as a prominent part of the substantive aspects of that analysis. That analysis attempted to project future design levels based on the modeled results, a method known as design value rollback. This method explicitly used the results of the grid modeling to estimate air quality benefits from Clean Air programs implemented through 2007. The photochemical grid model results were also used to estimate the air quality benefits from EPA's proposed ozone transport program. By subtracting the model's predicted improvements from the current design values, New York predicted that its design values in 2007 would be 118-122 ppb. 45 EPA supplemented New York's analysis by evaluating different years, and having as its starting point an average of the design values for the years 1990, 1991, and 1992. The agency then calculated the percentage of peak ozone reductions from the base year to the model's predictions for the attainment year, a percentage it calls the Relative Reduction Factor. By applying the factor to the design levels of the base period, EPA estimated the design values for the attainment year. It concluded from these computations first that the varying results from different applications of the design value rollback supported its belief that there was uncertainty in the grid model's projections. It also concluded that New York's real design value in 2007 was likely to be about 129 ppb — close to, but not quite attaining the one-hour national air quality standards. 46 Such analysis is consistent with the language of the statute because under EPA's approach, grid modeling forms the foundation and principal component of the attainment demonstration. Each aspect of the weight of evidence analysis used data from the photochemical grid model, and the corrections were applied to the results of the model. The record suggests that this analysis was applied to correct for errors in the model, with an eye towards the ultimate goal of assessing whether the state plan provided for attainment by the deadline. It is not our charge to second guess the agency's scientific conclusions. If it has articulated a rational reason why weight of the evidence analysis was appropriate, and that reason finds support in the record, we must affirm it. See Motor Vehicle Mfrs. Ass'n of the United States v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29, 42-43, 103 S.Ct. 2856, 77 L.Ed.2d 443 (1983). 47 Accordingly, we are persuaded that the EPA's analysis was based on a reasonable interpretation of the Act and was applied after satisfactory evaluation of the relevant data. EPA has articulated a rational explanation for its actions based on the facts found. That is all that is required.
48 Petitioner also believes that EPA's supplemental analysis contravenes its own regulations. Those rules provide that [t]he adequacy of a control strategy shall be demonstrated by means of applicable air quality models, data bases, and other requirements specified in appendix W of this part (Guideline on Air Quality Models). 40 C.F.R. § 51.112(a)(1). Appendix W in turn offers broad guidance on the use of grid modeling, including recommended types of models, design considerations, and a discussion of uncertainty of the models. 40 C.F.R. pt. 51 app. W § 6.1 (2002). The appendix recommends the Urban Airshed Model for photochemical grid modeling, and refers users to EPA's Guideline for Regulatory Application of the Urban Airshed Model (Guideline). See id. § 6.2.1(a). 49 EPA first issued the Guideline in 1991 and then revised it in 1996 and subsequently. The 1991 Guideline provided that there should be no predicted daily maximum ozone concentrations greater than 0.12 ppm anywhere in the modeling domain, and if attainment is not demonstrated, the model must be repeated as an iterative process until attainment is shown for each modeled episode. Office of Air Quality Planning and Standards, U.S. EPA, Guideline for Regulatory Application of the Urban Airshed Model, 14, 63 (July, 1991) [hereinafter Guideline for Regulatory Application]. However, the 1996 revision superseded this strict language and allowed more flexibility in the testing to track more closely the limited exceedances permitted by the air quality standards. See Guidance on Modeled Results, supra, at § 2. The 1996 guidance also recognized uncertainties in the grid models that practitioners were beginning to identify through experience. 50 Petitioner contends that the 1991 Guideline is a rule because it was incorporated into Appendix W and that, as a rule, the 1991 Guideline can only be changed through notice and comment rulemaking. 5 U.S.C. § 553. It believes that the later revisions were invalid because they were not adopted through formal procedures. Thus, petitioner maintains EPA's actions with respect to the New York plan were inconsistent with its own 1991 Guideline, which it claims is still in effect. 51 We agree with EPA that the Guideline is not a rule and that the subsequent revisions were effective notwithstanding the lack of formal rulemaking procedures. While Appendix W may only be amended by notice and comment rulemaking, it only refer[s] users to the Guideline for additional data requirements and procedures for operating this model. 40 C.F.R. pt. 51 app. W § 6.2.1(a). The language referring users is not mandatory, nor does it express an intent to incorporate the Guideline. Cf. PPG Indus., Inc. v. Costle, 659 F.2d 1239, 1250 (D.C.Cir.1981) (where rule requires use of procedures described in guideline, then guideline intended to be mandatory and must be adopted through formal notice and comment procedure). The Guideline on its own terms is not legislative, but rather provides recommendations and procedures for conducting an analysis with the Urban Airshed Model. Guideline for Regulatory Application, supra, at 1. Hence, the Guideline is simply a useful manual and may be revised without formal procedures, although lack of such procedures also means that the Guideline has not the independent force of law. See Used Equip. Sales, Inc. v. Dep't of Transp., 54 F.3d 862, 867 (D.C.Cir.1995) (guidelines not promulgated pursuant to notice and comment rulemaking have no legal effect apart from the agency's ability to persuade this court to the view they reflect). 52 Petitioner further challenges the supplemental methodology on the ground that part of EPA's analysis violated Appendix W's mandate that [p]roportional (rollback/forward) modeling is not an acceptable procedure for evaluating ozone control strategies. 40 C.F.R. pt. 51 app. W § 6.2.1.e. Rollback is defined as [a] simple model that assumes that if emissions from each source ... are decreased by the same percentage, ambient air quality concentrations decrease proportionately. Id. § 14.0. When EPA calculated the additional emissions reductions New York needed to effectuate in order to attain the ozone standard, it used a method of estimating reductions in emissions of ozone precursors that assumed a linear relationship between those reductions and the corresponding reduction in ozone concentration. See Approval and Promulgation of Implementation Plans, New York, 67 Fed.Reg. at 5176-77. 53 EPA asserts that linear rollback has always had some degree of validity and widespread acceptance, and that the prohibiting clause of Appendix W was intended only to prohibit linear rollback as the sole basis for demonstrating attainment. When rollback is based on modeled test results, and addresses only a limited reduction in ozone concentrations, the agency maintains the method does not suffer from the same simplistic failures as when it is applied to the whole program. EPA believes linear approximations can be helpful in circumstances where (1) only a small increment of the overall ozone reduction is being addressed and (2) the relationship between precursors and ozone is derived from locally modeled or measured air quality. Id. 54 When interpreting its own regulations, set forth in a final rule, the agency's interpretation is controlling unless plainly erroneous or inconsistent with the regulation. Auer v. Robbins, 519 U.S. 452, 461, 117 S.Ct. 905, 137 L.Ed.2d 79 (1997). We believe that EPA's interpretation satisfies that highly deferential standard. The definition of proportional rollback as a simplistic model using a blanket assumption leaves room for EPA to conclude that a comparable type of analysis is not prohibited when it is based on measured data and applied only to a narrow range of effects. Whether and to what extent linear relationships exist between assorted variables and ozone reduction is a matter for the expert judgment of EPA, and its determination that the analysis used here does not contravene Appendix W is not unreasonable. 55 Consequently, since the 1996 revision and subsequent revisions to the Guideline were effective, and because those revisions contemplate the use of supplemental analysis, including weight of evidence, EPA's approval of the New York plan did not contravene its own rules or guidelines.