FILED United States Court of Appeals Tenth Circuit 

### July 24, 2018 Elisabeth A. Shumaker Clerk of Court PUBLISH
UNITED STATES COURT OF APPEALS
TENTH CIRCUIT

ROBERT UKEILEY, Petitioner, v. No. 16-9556 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY; and ANDREW WHEELER, * Acting Administrator, United States Environmental Protection Agency, Respondents.

APPEAL FROM THE UNITED STATES ENVIRONMENTAL PROTECTION ADMINISTRATION (AGENCY NO. EPA-R08-OAR-2015-0042)

Vincent P. Calvano, Vincent P. Calvano, LLC, Boulder, Colorado, for Petitioner. Allan D. Greenberg, Attorney, Environment & Natural Resources D ivision (Jeffrey H. Wood, Acting Assistant Attorney General, United Sta tes Department of Justice, Denver, Colorado, and Randall Cherry, Office of Reg ional Counsel, Region 8, and Jonathan Skinner-Thompson, Office of General Coun sel, United States Environmental Protection Agency, with him on the brief) United States Attorney’s Office, Denver, Colorado, for Respondents.

* Pursuant to Federal Rule of Appellate Procedure 43(c)(2), Andrew Wheeler is substituted for Scott Pruitt as the respondent in th is case.Before TYMKOVICH , Chief Judge, SEYMOUR , andMcHUGH , Circuit Judges.

TYMKOVICH , Chief Judge.

This petition for review challenges the Environmental Protectio n Agency’s 2016 decision to certify Colorado’s compliance with air qualitystandards despite a number of days in which Colorado failed to meet those standar ds. Robert Ukeiley is a local property owner who suffers from a lun g condition worsened by airborne particulates. He spends substantial time at a residence near Lamar, Colorado, a town on Colorado’s eastern plains. Like the rest of the high plains region, Lamar experiences many windy days, and the resul ting dust storms generate airborne particulate pollution that affects its reside nts. Due to this pollution, between the early 1990s and 2005 the Environmental P rotection Agency designated Lamar as a nonattainment area under the CleanAir Act. To achieve attainment, Lamar needed to comply with National Amb ient Air Quality Standards (Standards) promulgated by the EPA. The Stan dards impose a variety of regulatory requirements designed to reduce the expos ure of the public to dangerous levels of airborne pollutants. To achieve complia nce with the Standards, Colorado developed a state implementation plan in 19 94. In 2002, Colorado requested the EPA to redesignate the Lamar area as an attainment area and submitted a ten-year maintenance plan to demonstrate expect ed compliance

-2-through 2015. The EPA approved the plan in 2005 and redesignat ed Lamar as an attainment area. In 2013, as part of its requirement for achieving attainment, C olorado submitted its second proposed ten-year maintenance plan for the Lamar area. Along with its submission, Colorado asked the EPA to exclude a number of days in which Lamar’s airborne pollutants exceeded the Standards. T he EPA concurred on the request for some of the days and approved the plan in 2016. Ukeiley challenges that 2016 approval in his petition for revie w. He contends the EPA abused its discretion by granting Colorado’s r equest to exclude certain instances in which airborne dust exceeded the Standards . As we explain, the EPA did not err in approving Colorado’s maintenance plan. The EPA’s interpretation of the Clean Air Act and its application of thatinterpretation are correct. And the EPA’s regulations, related guidance, and the extensive administrative record all support the EPA’s decision. We there fore deny Ukeiley’s petition for review. 

### I. Background We start with an overview of the statutory and regulatory schem e. We then discuss the specifics of Colorado’s request to exclude some ins tances in which it failed to comply with the Standards and the EPA’s rationale in granting the request.

-3-A. Clean Air Act The Clean Air Act requires the EPA to establish National Ambien t Air Quality Standards aimed at reducing airborne dust and soot part icles in the air. Pursuant to that statutory mandate, the EPA adopted Standards t hat set pollution limits for various air contaminants, including the po llutant at issue here—fugitive dust or s oot particles known as “PM- 10.” P M-10’ s are “particulate matter with an aerodynamic diameter less than or equal to a nom inal ten micrometers.” 42 U.S.C. § 7602(t). The Standards applicable h ere are based on the daily particulate amounts for a geographic area averaged ov er a longer period of time. See 71 Fed. Reg. 61,144 (Oct. 17, 2006). A geographic area meets the Standards if it averages one or fewer 24-hour periods of concen tration above the limit per calendar year, averaged over a three-year period. See 40 C.F.R. 50.6 and 40 C.F.R. part 50, appendix K. The Clean Air Act requires the EPA to designate any geographic location that does not meet this standard as a “nonattainment area.” 42 U.S.C. § 7513(a). If the EPA designates a nonattainment area within a state, the state is required to submit a corrective plan that will ensure compliance with the a ir quality standards. 42 U.S.C. § 7513a(a)(2)(A). Once a state achieves compliance, it can request the EPA to redesignate the nonattainment geographic area. 42 U.S.C . § 7407(d)(3). To be eligible for redesignation, the state must submit a plan that describes how the state will maintain air quality compliance for ten or more years after the

-4-redesignation. 42 U.S.C. § 7505a(a). And at the eight year ma rk after redesignation, the state must further revise its plan to demons trate how it will maintain its air quality for an additional ten years following expiration of the initial ten-year maintenance period. 42 U.S.C. § 7505a(b). B. Exceptional Events Rule The air quality standards are subject to certain exceptions und er the Clean Air Act. Section 7619 directs the EPA to promulgate “regulations governi ng the review and handling of air quality monitoring data influenced b y exceptional

events .” 42 U.S.C. § 7619(b)(2) (emphasis added). Under § 7619(b)(1 ), an event is exceptional if it meets four statutory conditions: (1) it “a ffects air quality”; (2) it is not “reasonably controllable or preventable”; (3) it is “an event caused by human activity that is unlikely to recur at a particular locati on or a natural event”; and (4) the EPA has certified the exceptional event criteria ha ve been met. 42 U.S.C. § 7619(b)(1)(A). If all of these conditions are met, th e EPA may exclude certain air-quality monitoring data when determining whether ornot a state complied with its implementation plan. Consistent with its statutory mandate, the EPA has promulgated rules for administration of its exceptional events regime and specific gu idelines as to what constitutes an exceptional event. Under the EPA’s Exceptional Events Rule (Rule), “[a] State . . . may request the Administrator to exclu de data showing

-5-exceedances or violations of any national ambient air quality s tandard that are directly due to an exceptional event . . . .” 40 C.F.R. 50.14( a)(1)(ii). In defining “exceptional event,” the Rule largely tracks the st atutory definition: Exceptional event means an event(s) and its resulting emissions that affect air quality in such a way that there exists a clear causal relationship between the specific event(s) and the monitored exceedance(s) or violation(s), is not reasonably controllable or preventable, is an event(s) caused by human activity that is unlikely to recur at a particular location or a natural event(s). 40 C.F.R 50.1(j) (second emphasis added). In addition, the EPA defines “natural event”:
Natural event means an event and its resulting emissions, which may recur at the same location, in which human activity plays little or no direct causal role. For purposes of the definition of a natural event, anthropogenic sources that are reasonably controlled shall be considered to not play a direct role in causing emissions. 40 C.F.R 50.1(k) (second emphasis added). The Rule’s definitions crystalize a basic foundation for the co ntours of exceptional events. To supplement these definitions, the EPA h as also issued detailed technical guidance for exceptional events in various c ircumstances such as high wind events.

-6-C. High Wind Guidance The EPA issued guidance for applying the Rule to high wind even ts, such as those that generate fugitive dust. See Treatment of Data Influenced by Exceptional Events, 72 Fed. Reg. 13,560 (Mar. 22, 2007). In pa rticular, the guidance instructs that for a state to be eligible for an exclu sion, it must meet a number of technical elements. These elements include a showing that the high wind event (1) was not reasonably controllable; (2) caused the attainment area to be out of compliance with the standards; (3) was a natural even t; and (4) was in excess of natural historical fluctuations. 1

1 Elements for the Technical Demonstration of High Wind Dust Ev ents • Air agencies’ demonstrations must address the following six technical elements under the EER before the EPA can concur on a high wind dust event demonstration: 1. whether the event was not reasonably controllable or preventable (nRCP) 2. whether there was a clear causal relationship (CCR) 3. whether there would have been no exceedance or violation but for the event (NEBF) 4. whether the event affects air quality (AAQ) 5. whether the event was caused by human activity unlikely to recur or was a natural event (HAURL / Natural Event) 6. whether the event was in excess of normal historical fluctuations (HF) R., Vol. 3 at 1960 (EPA, Interim Guidance on the Preparation of Demonstrations in Support of Requests to Exclude Ambient Air Quality Data Affected by High (continued...)
-7-As with the Exceptional Events Rule, the guidance tracks the st atutory language concerning the frequency of exceptional events. The E PA requires exceptional events attributable to human activity be “unlikely to recur,” but it permits recurring “natural event[s].” R., Vol. 3 at 1960

. “The EPA acknowledges that natural events, such as high wind dust events, can recur a nd still be eligible for exclusion under the [Rule]. Therefore, events do not neces sarily have to be rare to satisfy this element.” Id. at 1978. But the EPA guidance still requires all exceptional events, including natural events, to be outside “no rmal historical fluctuations.” Id. To determine whether an event is in excess of historical fluctuations, the EPA uses a “weight-of-evidence approach.” Id. In this approach, no absolute numerical value or percentile of the event’s relati ve rarity will guarantee a successful demonstration that the event was in factoutside normal historical fluctuations. Instead, the EPA uses a holistic methodology looking to factors such as meteorological and soil conditions, in additionto statistical data about the event’s frequency. D. Colorado’s Compliance with the Standards In 1991, the EPA designated Lamar as a nonattainment area. 56 Fed. Reg. 56,735 (Nov. 6, 1991). As a result, Colorado was required to d evelop and institute

1 (...continued) Winds Under the Exceptional Events Rule (May 2013)) (emphasis added).

-8-a State Implementation Plan, which the EPA approved in 1994. I n 2005, the EPA redesignated the Lamar area as attainment and approved Colorado ’s ten-year maintenance plan. In 2013, Colorado submitted a revised ten-ye ar PM-10 maintenance plan to the EPA that would ensure attainment throug h 2025. For approval of its revised maintenance plan, Colorado had to s how that it was in compliance with the Standards. As explained above, thatmeant demonstrating that the Lamar area did not exceed the applicable Standard for more than one-day-per-year on a rolling three-year average. Over th e period between 2001 and 2015, the Lamar area experienced numerous exceedances of the Standard. Colorado asked that 55 of these exceedances be set a side as excludable high wind events. In support of its request, Colorado submitted meteorological an alysis for each of these events to show there would have been no exceedanc e but for the high wind event. The analysis included comparisons to historical wi nd fluctuations and other information suggesting the winds were aberrational on the se occasions—even though high winds might be expected with some le vel of frequency in the area. E. The EPA’s Decision and Rationale The EPA granted Colorado’s request for 34 of the 55 flagged exc eedances. It found Colorado adequately showed each of the 34 events met the criteria listed in the guidance for high wind exceptional events: each event wa s not reasonably
-9-controllable or preventable; a causal relationship existed betw een correlation data and wind speeds; reasonable controls were implemented and enfor ced; the wind speed was high enough to overwhelm the controls; the event was outside historical fluctuations; and it was a natural event. After examining the data and making an initial determination th at it would exclude the exceedances, the EPA solicited public comments on i ts proposed decision. After receiving only one comment, the EPA issued a f inal rule that approved Colorado’s plan revision for PM-10 and excluded the 34 exceedances on the basis that these were exceptional events. 

### II. Analysis Ukeiley claims the EPA wrongfully categorized these 34 exceedan ces where air quality exceeded the maximum PM-10 standard. He argues the exclusion criteria were not met because windy days in Lamar are common oc currences, therefore meeting neither the statutory nor the regulatory defi nitions for exceptional events. As a result, he contends the EPA arbitrari ly and capriciously applied the exceptional events standard found in the Clean Air Act. 2

2 The EPA argues Ukeiley’s challenge is untimely. In the EPA’s view, Ukeiley is arguing that the EPA should have included an additio nal factor of “rarity” when classifying an exceptional event. In short, the EPA claims Ukeiley is challenging the Exceptional Events Rule itself, a challenge he should have brought when the Rule was promulgated in 2007. We do not agree. Ukeiley specifically challenges the EPA’s dec ision as (continued...) -10-A. Standard of Review We review agency action under the Administrative Procedure Act. “The APA requires courts to consider agency action in conformity with the agency’s statutory grant of power, and agency action is unlawful if it i s ‘in excess of statutory jurisdiction, authority, or limitations, or short of statutory right.’” Sinclair Wyoming Ref. Co. v. EPA , 887 F.3d 986, 990 (10th Cir. 2017) (citing 5 U.S.C. § 706(2)(C)). Our APA review is limited. “Under the APA, we will not set asi de agency action unless it is procedurally defective, arbitrary or capric ious in substance, or manifestly contrary to the statute.” US Magnesium, LLC v. EPA , 690 F.3d 1157, 1164 (10th Cir. 2012) (internal quotation marks and citations o mitted). “Agency action is arbitrary or capricious if the agency has relied on f actors which Congress has not intended it to consider” or “entirely failed to conside r an important aspect of the problem.” Id. (internal quotation marks and citations omitted). An agency’s decision is likewise arbitrary if it “offered an explanation for its decision that runs counter to the evidence before the agency, or is so i mplausible that it could not be ascribed to a difference in view or the product of agency expertise.”
Id. (internal quotation marks and citations omitted). Accordingly, although our

2 (...continued) inconsistent with “the statutory term ‘exceptional event’ and i ts regulatory definition.” Pet. Br. at 8. This is a challenge to the decisi on and its statutory provenance, not to the Rule itself. -11-inquiry is “searching and careful,” our “review is ultimately anarrow one.” Maier
v. EPA , 114 F.3d 1032, 1039 (10th Cir. 1997)

. When reviewing agency action, we apply the familiar analytical framework set forth in Chevron v. Natural Resources Defense Council , 467 U.S. 837 (1984). Under Chevron , we first consider if “Congress has directly spoken to the pre cise question at issue” and, if so, we apply the statute’s plain mea ning and the inquiry ends. Sinclair , 887 F.3d at 990 (quoting Chevron , 467 U.S. at 842–843). But “if the statute is silent or ambiguous about the question at issue” then “we defer to the authorized agency and apply the agency’s construction so long a s it is a reasonable interpretation of the statute.” Oklahoma v. EPA , 723 F.3d 1201, 1207 (10th Cir. 2013). At the second Chevron step, we defer to administrative determinations on matters of technical evaluation and judgment. See City of Albuquerque v.
Browner , 97 F.3d 415, 427 (10th Cir. 1996) (“We decline to second-guess the EPA’s technical determination, which is entitled to substantial deference . . . .”). Our review here, therefore, starts with the definition of an ex ceptional event set forth by Congress in § 7619(b). If we find no ambiguity, o ur inquiry ends. If we find some ambiguity, we proceed to analyze the reasonablenes s of the EPA’s interpretation of congressional intent as set forth in the Exce ptional Events Rule. Finally, we ask whether the EPA’s application of the Rule to Co lorado’s request was arbitrary or capricious.

-12-B. Application of the Standard s Ukeiley first contends the EPA’s exclusion of the high wind exc eedances violates the plain meaning of 42 U.S.C. § 7619(b)(A)(iii). Spe cifically, he maintains the high frequency and regularity of these natural wind events does not make them “exceptional” under the statute. As he sees it, the “EPA can only exclude monitoring data that is rare and exceeding the usual ,” Pet. Br. at 32 (emphasis added), and he points to dictionary definitions for s upport. For instance, Black’s Law Dictionary defines “exceptional” as “out of the ordinary”; and the Merriam-Webster Collegiate Dictionary defines “exceptio nal” as “forming an exception: rare.” Pet. Br. at 32. Both definitions imply alimit on the frequency of any event, including a “natural event.” Ukeiley therefore concludes that since windy days in the Lamar area happen frequently, theyshould not be eligible for exclusion as an exceptional event. Because the Ex ceptional Events Rule varies from his interpretation of the statute, Ukeiley arg ues the EPA’s application of it here is arbitrary and capricious. We disagree. “When a statute includes an explicit definition, we must follow that definition, even if it varies from that term’s ordi nary meaning.” Stenberg v. Carhart , 530 U.S. 914, 942 (2000). Here we find no ambiguity. In § 7619, “exceptional event” functions as a two-word term of art . In defining the term, Congress provided several guideposts for interpreting the phrase: these events must “affect air quality”; not be “reasonably controllab le or preventable”;
-13-and be “an event caused by human activity that is unlikely to r ecur at a particular location or a natural event.” 42 U.S.C. § 7619(b)(A) (emphasis added). Furthermore, Congress specifies what cannot be an exceptional e vent: “stagnation of air masses or meteorological inversions”; “a meteorological event involving high temperatures or lack of precipitation”; or “air pollution relating to source noncompliance.” 42 U.S.C. § 7619(b)(B). These requirements se rved as a starting point for the EPA’s rulemaking to further define the boundaries of exceptional

events. Of great importance here, the congressional definition makes a distinction between human-causedevents and natural events. The EPA can only qualify a human-caused event as an exceptional event if it is unlikely to recur—meaning the event was a one-off that should have no long-term or recurring health-related consequences. For instance, human-induced recurring agricultur al practices would not be eligible for exclusion as exceptional events. By contra st, the statute’s definition does not include the same “unlikely to recur” limitation for natural events, such as high wind days. The import of this difference is clear: Congress did not exclude recurring natural variations from its definitio n of “exceptional
event.” We therefore disagree with Ukeiley’s interpretation of the statute and find the statute clear and unambiguous. And since the EPA’s Rule co mplies with the

-14-statute’s plain meaning, we cannot find its application here arbitrary and capricious. Additionally, both the Rule and the interim guidance outline fa ctors for classifying exceptional events derived from the statute. Speci fically, the EPA instructs state agencies seeking exclusions of exceedances to d emonstrate that exceedances—including those resulting from natural events—are n ot reasonably controllable, that the high wind actually caused the exceedance s, and that the events exceeded normal historical wind fluctuations. This meth odology confirms high wind events that recur based on local conditions found on the Colorado plains can qualify as exceptional events as long as they meet certain criteria. 3 Ukeiley further argues that even if the Rule and interim guidan ce reasonably interpret the statute, the EPA’s decision was still arbitrary a nd capricious because it was based on faulty reasoning and insufficient evidence. Bu t the record is clear that the EPA relied on considerable wind and meteorological dat a in reviewing Colorado’s application for exclusion. Colorado supported its r equest for an exclusion with reams of technical data, in accordance with the Rule and the EPA’s guidance. And for each set of exceedances excluded, the EPA ex amined multiple factors. For example, it looked at the percentile of the measurements based on location; whether any exceedances since 2005 were caused by eve nts other than

3 It follows that, even if we discerned some ambiguity, we woul d still uphold the EPA’s decision as a reasonable construction of the s tatute. -15-high winds from distant areas carrying PM-10 dust; soil conditi ons; and meteorological conditions. See, e.g. , R., Vol. 3 at 599, 860, 1060, 1161, 1407, 1692, 1874. Its decision thus relied on technical judgments gr ounded in data—not in arbitrariness or caprice. We conclude that in both promulgating the Rule and applying it, the EPA’s actions were not arbitrary or capricious. 

### III. Conclusion Socrates is said to have observed, “the same wind is blowing, a nd yet one of us may be cold and the other not.” The Dialogues of Plato 517 (Benjamin Jowett, trans., Encyclopedia Brittanica 1952). For the winds of Lamar, Ukeiley hopes his personal interpretation of “exceptional” will override Congress ’s statutory definition and the EPA’s reasonable application of it. But we are bound by law and reasonable decisions applying it. Therefore, we DENY the petition.

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