Opinion ID: 786322
Heading Depth: 3
Heading Rank: 2

Heading: EPA Regulations

Text: 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 However, the 1996 revision superseded this strict language and allowed more flexibility in the testing to track more closely the limited exceedances permitted by the air quality standards.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.