February 13, 2023 / KELLY HANSON
Current requirements addressing regional haze are ineffective, as evidenced by the fact that many national parks suffer from significant air pollution, notably in the State of California. A study by the National Parks Conservation Association reports that out of 417 parks, 401 had air pollution issues related to one or more of the following: visibility, damage to ecosystems, climate change, and respiratory-related concerns. In some cases, the pollution is due to industry sources. For example, the Grand Canyon National Park receives polluted air from various sources, including mining and power plants using coal in the Four Corners area.
Congressional mandates require regulation of air pollution as defined by the Clean Air Act (CAA), which originally was enacted in 1955 with substantial revisions in 1970, 1977, and 1990. Pursuant to the CAA, the Environmental Protection Agency (EPA) must set National Ambient Air Quality Standards (NAAQS) that apply to certain air pollutants. When areas within a state do not meet the standard, the governor will designate them as nonattainment areas. Within three years of the application of the NAAQS, all states are required to institute a State Implementation Plan (SIP) that sets forth measures to meet the standards. When setting the restrictions, consideration of pollution that drifts into other states must be evaluated under the “‘Good Neighbor Provision.’” If the state’s SIP plan does not meet requirements under the CAA, the EPA must prepare a Federal Implementation Plan (FIP) instead. Other provisions in the CAA include programs setting emissions standards, cap-and-trade for acid rain, prevention of deterioration where air is clean, phasing out chemicals that affect the ozone, and elimination of regional haze in areas designated as national parks or wilderness. This last provision is known as the regional haze rule (RHR).
In 2018, the EPA suggested that the CAA’s RHR has made considerable improvements due, at least in part, to other provisions of the CAA. This position by the Trump administration indicates that the RHR is duplicative with other provisions in the CAA, but would the decision to water-down the RHR’s measures lead to noticeably worsened aesthetic and environmental conditions? Is the congressional mandate to address haze met, if the agency allows fewer procedural requirements? If it is, will it make any difference in the way states address plans to reduce haze? Contrary to the assumptions of duplication, recent issues demonstrate that the RHR is not redundant.
On August 20, 2019, the Director of the Regional Air Division signed a memorandum entitled, “Guidance on Regional Haze State Implementation Plans for the Second Implementation Period.” While the memorandum notes that the guidance is non-binding, it replaces the 2016 draft guidance and reflects the EPA’s position with regard to the SIP plans. The EPA also provided clarifications to the guidance ahead of the deadline for the state SIP plans, which was July 31, 2021.
The EPA guidance is intended to provide a detailed explanation of the reform roadmap, which was issued in 2018 and suggests that emission control can be addressed by other state and federal CAA programs. The guidance may be interpreted as allowing states to avoid visibility considerations and omitting instructions concerning identification of sources of pollution emissions. The purpose of the policy was to streamline plan requirements for pollution reduction around federal parks and wilderness lands and to focus the states on other CAA provisions that have visibility goals. The reform roadmap reflected the EPA’s plan to reform the RHR and promote the executive branch’s economic policies.
In Part II, this paper addresses the background of the RHR including the political ramifications, as well as the statutory and judicial authorities and limitations of the requirements. Next, Part III describes the specific technical aspects of the RHR requirements. In Part IV, the paper explores the changes initiated by the Trump administration and their effects, noting items that did not remain. Part V makes predictions about additional changes. Finally, Part VI analyzes the issue of duplicative legislation with regard to the function of the RHR.
II. Background: Regional Haze Rule
Unlike the other provisions of the CAA and other pollution measures, the RHR focuses on safeguarding nature and ecosystems in protected federal lands rather than on public health. This contributes to its vulnerability to political pressure. The science behind the RHR indicates that minimal exposure can reduce visibility substantially, which means that strict enforcement would limit a wide range of economic development. Accordingly, the federal mandates can have a severely limiting effect on the states’ use of the land, and the states’ regulation of private businesses that affect it. The RHR has improved visibility in some of the parks in the western states from 90 to 120 miles, while eastern parks have improved from 50 to 70 miles.
The RHR has its origins in a 1999 addition to the rules implementing the CAA. The RHR governs two issues. First, it establishes the deadline for attaining natural conditions for visibility in Class 1 areas as the year 2064. Class 1 areas refers to national parks and federal wilderness lands. Second, it requires the states to show efforts toward making “reasonable progress” at ten year intervals. The RHR added to the existing efforts to reduce pollution including emission controls and other standards. This rule promoted both flexibility and regional cooperation in developing strategies under a multi-state approach.
The requirement to improve visibility is a statutory one. It extends to those areas that are mandatory Class I, if the EPA determines that “visibility is an important value of the area.” Although pollution can affect general health and other sensory functions such as olfactory and, in some cases, auditory, those are not necessarily addressed by the RHR. The federal statute mandates began in 1977, and these requirements included “modeling techniques (or other methods) for determining the extent to which manmade air pollution may reasonably be anticipated to cause or contribute” to the impairment of visibility. The regulations also would set methods for “preventing and remedying” pollution. The legislation allows for the exemption of a stationary source, if by itself or combined with other emitters, would not significantly impair visibility in a Class I area. The exemption does not apply to larger-capacity, “fossil-fuel fired” powerplants, unless it demonstrates that it is not located in such a close proximity to the protected areas that it would “cause or contribute to significant impairment of visibility in any such area.” The federal land manager must concur with the exemption.
If the source is covered by the RHR, then the state must impose best available retrofit technology (BART). An earlier RHR allowed one of the factors testing for BART to be based upon an “’area wide’” or group basis. The D.C. Court of Appeals determined that this provision infringed upon the states’ authority under the CAA.
III. Regional Haze Rule Requirements
The program requirements for regional haze involve a state plan that must be submitted to the EPA. The elements of the plan include setting progress goals, calculating baseline and visibility conditions, establishing a long-term strategy, and then monitoring strategy requirements as well as implementation.
First, the goals must consider economic factors and the rate of progress needed to achieve natural visibility by 2064. Each state must consult with other states that contribute to the impairment. If the states disagree, the state must incorporate in its plan the measures it employed to resolve the disagreement.
Secondly, the state calculates the baseline using conditions from 2000 to 2004. The conditions are assessed with monitoring data that evaluates the “most impaired and least impaired days,” using available data and analysis techniques. Also, the first plan includes the “number of deciviews by which baseline conditions exceed natural visibility conditions for the most impaired and least impaired days.”
Third, the long-term strategy must incorporate means to achieve the progress goals, including schedules for compliance and emissions limits that are enforceable. Here, again, the state must consult with other states that will be affected by its emissions in a Class 1 area, and whose emissions will affect its Class 1 area. The plan must include provisions to ensure the state will meet any required portion of reduction as agreed upon in a regional planning process. In listing all anthropogenic sources, it should consider “major and minor stationary sources, mobile sources, and area sources.” Also, the strategy must be based upon consideration of at least seven factors: other reduction programs, mitigation of construction, limits and schedules for goals, source schedules, smoke management, enforceability, and net effect of changes of emissions.
Finally, the plan must include the monitoring strategy along with an implementation plan. States can participate in the Interagency Monitoring of Protected Visual Environments (IMPROVE) network or use other authorized means and must comply with reporting and record-keeping requirements. Revisions to the plans have similar requirements. These include calculating the baseline, formulating the long-term strategy, establishing reasonable progress goals, and monitoring.
IV. The 2017 Regulatory Revisions and Later Guidance
The revisions in 2017 did not eliminate significant requirements of the RHR. Updates to the 1999 RHR addressing state requirements became final on December 14, 2016 and were published on January 10, 2017. The EPA’s revisions purported to clarify the interpretations of the RHR in place since inception. These include the focus on long-term goals, factoring contributions of other states’ pollution, and “setting reasonable progress goals that provide for a slower rate of progress than that needed to attain natural conditions by 2064.”
In addition to coordination among regional states, the RHR addresses consultation between the states and the federal land managers. The 1999 RHR required that the state provide the manager an opportunity to consult before the public hearing and discuss assessments and recommended strategies. With the revisions for the 2017 RHR, the agency proposed early consultation requirements to ensure that the manager’s concerns could be incorporated in the long-term strategy. Second, the 1999 RHR required continuing consultations regarding SIPs and other visibility programs. The 2017 version did not recommend changes to this part of the RHR. Additionally, the 2017 version retained the periodic revision updates to the monitoring strategy but eliminated them for the progress reports.
Thus, the updates in 2017, as reflected by this section, did provide some minor editing of the requirements of the RHR. The updates also encouraged participation with tribes regarding visibility issues, although the CAA and RHR did not require it. The purpose of the revisions to the regulations in 2017 was to streamline the administrative requirements the agency found to be “burdensome.”
Similarly, the final guidance aimed to streamline the processes, and it did make some important changes to the draft guidance. The purpose of the guidance is to assist with developing plans by reducing the burden on states and leveraging other pollution programs’ reduction of pollution. In the section covering consultation with other states, the guidance states that the requirements are procedural. It would require only that the states share and consider the data, but it would not require that the states duplicate their thresholds, approaches, or measures. Further, the guidance recommends that a state with concerns about pollution effects from a neighboring state request adoption of specific measures to reduce pollution from the sources.
Additionally, the 2019 guidance revised the 2016 draft in several respects. For example, the 2016 draft indicated that the states would need to account for 80 percent of the relevant sources. In other words, the 2016 version required states to evaluate at least 80 percent of their pollution sources for compliance purposes, and anything less would not be considered reasonable. That requirement was deleted from the 2019 version of the guidance.
Another missing element is a provision in the 2016 draft that could impose additional pollution controls on older facilities that use coal to generate power. The effect of this revision is lessened by the fact that the previous ten year SIPs addressed the coal plants, and most of them have been either upgraded or closed down. Nevertheless, these changes are significant and could result in more pollution emissions that contribute to haze issues. The remaining sources left to regulate include prescribed fires and petroleum-based facilities. Ultimately, the states can proceed with more flexibility, which helps the states that cannot or do not want to meet the requirements, provided that the state acts reasonably.
V. Possible Forthcoming Revisions to the 2017 Regional Haze Rule
Presumably, the EPA will continue to evaluate additional requirements under the RHR. Subsequent to the 2017 revisions, the EPA posted an announcement on its website that it intends to revisit the RHR again. The agency intended to update provisions relating to the reasonably attributable visibility impairment (RAVI) requirements, consultation with the federal land managers, and possibly other sections of the RHR.
Rarely used, the National Park Service has the ability under RAVI to identify a pollution source near the park lands as a significant source of emissions and, with state consent, make plans for reducing them. The RHR addresses large-scale areas with pollution from multiple sources in federal Class I areas. Conversely, the RAVI program can provide a mechanism to address either a single source or sources in smaller sections that are identified as causing the visibility impairment. If the EPA eliminates this seemingly forgotten provision, an objection may be difficult to justify.
VI. Duplication of Efforts
Although the RHR does not allow states to enforce emissions reductions against another state, other provisions may assist with interstate air pollution. The EPA issued the cross-state air pollution rule (CSAPR), after the D.C. Circuit court invalidated its predecessor in 2008. This is a cap-and-trade provision that addresses pollution across state lines. The CSAPR requires 27 states to reduce power plant emissions of ozone or fine particles that travel to other states. In 2014, the United States Supreme Court upheld the CSAPR, which allows the EPA to dictate the proportion of emission reduction among states. This provision could provide more effective remedies than the consultation provisions of the RHR.
Recent rules implementing changes to CSAPR have been challenged in court, however. The EPA determined that all states would meet the NAAQS 2008 standard for ozone by 2023, and it promulgated a rule to close-out this CSAPR provision. Second, the CSAPR update proposed pollution budgets, using readily available and cost-effective pollution controls. The D.C. Circuit rejected both rules, vacating the close-out and remanding the update. As a result of the lack of FIPs for twenty states, various environmental groups filed a lawsuit on February 7, 2020 in that court seeking declaratory and injunctive relief against the EPA based upon these two previous rulings. Accordingly, the idea that CSAPR will replace RHR provisions loses steam in the wake of the efforts by EPA to abandon the CSAPR provisions and its requirements.
Additional problems arise when pollution stems from international sources. In one case, Mexican coal-fired plants released sulfur dioxide that impaired visibility in Texas’s Big Bend National Park. The Mexican government denied responsibility and noted that the emissions met Mexico’s standards. Presumedly, international agreements would be required to address all regional haze issues. In the meantime, states are permitted to treat international, anthropogenic sources as natural visibility conditions in calculating the 2064 endpoint.
The value in having the RHR is in the fact that it is regionally-focused to some extent and fosters cooperation between and among states. It does not, however, provide for enforcement against a neighboring state. Also, the requirement for federal land manager consultation may be helpful in bringing issues to light when attempting to influence the state to address certain sources. The RHR does not allow states to address sources on federal lands or on tribal reservations, although tribes may be permitted to comment. Theoretically, the other provisions in the CAA regarding interstate emissions may create some overlap with the RHR. If the other provisions of the CAA effectively limited or controlled pollution, then the special provisions for Class I areas under the RHR might not be needed. Evidently, the other provisions are not utilized or enforced, and further curtailments of the RHR will not solve the pollution problems in Class I areas.
Further, if the parks have higher levels of pollution than other areas, that seems to indicate a failure to make progress under the RHR, despite previously noted improvements. Certainly, the deleted provisions in the above-referenced guidance, which historically required reduction of emissions in a high percentage of sources, as well as measures to address coal-fired plants, would be useful in meeting the progress goals and target date. Alternatively, if the states meet their target goals under CSAPR, the regional haze may be reduced or eliminated, but this provision only applies to about half of the states.
Although there are multiple avenues for clearing haze, the EPA and partners can improve efforts by ensuring all states have a SIP or else a FIP in place. Additionally, revisions to the RHR should incorporate additional provisions to address identifying, monitoring, and reducing levels of pollution in the national parks and wilderness lands, either through existing provisions or another enforcement mechanism. The EPA should continue enforcement of Good Neighbor provisions and extend the area to include all 48 continental United States. Also, efforts to reduce pollution from outside the nation’s borders, including areas near Alaska, may be necessary to meet the RHR’s goal. In conclusion, the EPA position noted in the Director of the Regional Air Division’s 2021 clarification paper is that the RHR requirements must be met, though states may pursue other statutory provisions and methods to reduce emissions, thus ensuring a crisp, clear view of the treasured areas protected by this legislation.
Michael McGough, Pollution is a ‘significant’ problem at 401 national parks, report says (May 30, 2019) www.phys.org/news/2019-05-pollution-significant-problem-national.html. (A temporary policy regarding enforcement during the pandemic may have affected monitoring and report deadlines, however. See Memorandum from Susan Parker Bodine, Asst. Administrator, Environmental Protection Agency (March 26, 2020) EPA, https://www.epa.gov/sites/default/files/2020-03/documents/oecamemooncovid19implications.pdf.)
 Id. The pollutants that affect visibility include nitrogen oxides, sulfur dioxide, particulate matter, volatile organic compounds, and ammonia. EPA, Guidance on Regional Haze State Implementation Plans for the Second Implementation Period (August 20, 2019) at 11. EPA, https://www.epa.gov/sites/default/files/2019-08/documents/8-20-2019_-_regional_haze_guidance_final_guidance.pdf .
 Melissa Breyer, Nearly every US National Park is plagued by ‘significant’ air pollution (May 8, 2019) https://www.treehugger.com/us-national-parks-are-plagued-air-pollution-4855006 (citing www.nps.gov/grca/learn/nature/airquality.htm).
 Congressional Research Service, Clean Air Act: A Summary of the Act and Its Major Requirements, (February 25, 2020 and updated September 13, 2022) https://sgp.fas.org/crs/misc/RL30853.pdf (citing 42 U.S.C. §7401 et seq.)
 www.4cleanair.org (citing New York, et al. v. Environmental Protection Agency, 781 F.App’x *4, *5 (D.C. Cir. 2019)). The District of Columbia Court of Appeals (J. Millett) held that that EPA erred in denying New York’s petition regarding the CAA Good Neighbor provisions and remanded the case back to the EPA. US Courts, https://www.cadc.uscourts.gov/internet/opinions.nsf/59B283676622CF1F852585A5005203B9/$file/19-1231.CORRECTED.pdf, New York, et al. v. Environmental Protection Agency, No. 19-1231 (D.C. Cir. 2020).
 Id. at *6.
Congressional Research Service, supra note 4.
Memorandum from Andrew Wheeler, then-Acting Administrator, Environmental Protection Agency (September 11, 2018) Regional Haze Reform Roadmap, EPA, www.epa.gov/visibility/epa-releases-regional-haze-reform-roadmap. While recognizing that states may pursue various and sundry provisions of the CAA to reduce emissions, the EPA demands “rigorous reasonable progress analyses” that further the goals of visibility under the statutes and regulations. EPA, https://www.epa.gov/visibility/visibility-guidance-documents, Clarifications Regarding Regional Haze State Implementation Plans for the Second Implementation Period, Peter Tsirigotis, p. 2 (July 8, 2021).
EPA, supra note 2.
 Id. See EPA, www.epa.gov/visibility/draft-guidance-second-implementation-period-regional-haze-rule.
 Id. and EPA supra note 11. Although the District of Columbia and 35 states submitted a SIP, 15 states did not meet the due date. Finding of Failure to Submit Regional Haze State Implementation Plans for the Second Planning Period, 87 Fed. Reg. 52856 (August 30, 2022) (to be codified at 40 C.F.R. pt. 52).
 www.eelp.law.harvard.edu/2018/04/regional-haze-rule/ (Citing EPA, www.epa.gov/visibility/visibility-regulatory-actions. The memorandum by then-Acting EPA Administrator Andrew Wheeler stated that the RHR was adopted in 1999 and revised in 2017. His memorandum set out a path for the EPA’s Office of Air and Radiation to implement the regional haze program with states having primary roles, reduce planning “burdens,” and defer to other CAA programs to reduce emissions and increase visibility. It referenced the updated 2028 platform accounting for United States, as well as international, sources of pollution affecting Class I lands. Also, the roadmap indicated that EPA would pursue rulemaking to amend provisions related to the reasonably attributable visibility impairment (RAVI) rules, the consultation with Federal Land Manager sections, and possibly other requirements. See id.)
 Id. (Citing Sean Reilly, EPA unveils final haze guidelines, sparking enviro protest, E&E News (August 20, 2019) www.eenews.net/eenewspm/2019/08/20/stories/1061013699).
 Id. (Citing Reilly, supra note 16.) (The guidance was developed without transparency in contrast to previous administrations. Id. With a July 2021 suspense date, the guidance may be too late to influence the state plans. Id.) (Also citing Presidential Memorandum dated April 12, 2018, which directed the EPA to ensure efficiency and cost-effective measures for implementing programs including Regional Haze and National Ambient Air Quality Standards (NAAQS). Id. This directive ordered a review of all FIPs and development “at the request of affected States, consistent with law” to replace them with SIPs. Id.)
 Id. The EPA memorandum cites 83 Fed. Reg. 16761 (April 16, 2018), Presidential Memorandum to the EPA, Promoting Domestic Manufacturing and Job Creation—Policies and Procedures Relating to Implementation of Air Quality Standards. The President’s memorandum directs EPA to review FIPs and, where permissible, convert to SIPs, as well as providing, among other revisions, directions regarding consideration of international emissions.
 Arnold W. Reitze, Jr., Visibility Protection Under the Clean Air Act, 9 Geo. Wash. J. Energy & Envtl. L. 127, 161 (Spring 2019). But see Caitlin McCoy and Laura Bloomer, Regional Haze State Implementation Plans, Environmental & Energy Law Program, Harvard (April 23, 2018) (This article notes the public health benefits of the RHR in reducing pollutants such as nitrogen oxides, volatile organic compounds, and sulfur dioxide, which cause health effects and acid rain. Id.)
 McCoy and Bloomer, supra, note 19.
 Clinton and Gore on Clearing the Air in Our National Parks, 1999 WL 235189 (White House) (April 22, 1999). Vice President Gore announced the RHR at Shenandoah National Park in Virginia, noting that emissions trading options as well as a focus on regional partnership promised new avenues for combatting pollution in these special lands. Id.
 Id. There are five regional planning organizations (RPOs): Western Regional Air Partnership (WRAP), Central States Air Resources Agencies (CENSARA), Lake Michigan Air Directors Consortium (LADCO), Southeastern Air Pollution Control Agencies (SESARM), and Mid-Atlantic Northeast Visibility Union (MANE-VU). EPA, https://www.epa.gov/visibility/visibility-regional-planning-organizations.
 42 U.S.C. §7491 (2022). Visibility impairment is defined as “reduction in visual range and atmospheric discoloration.” 42 U.S.C. §7491 (g) (6) (2022). US Code, https://uscode.house.gov/view.xhtml?path=/prelim@title42/chapter85/subchapter1&edition=prelim
 Id. “Areas statutorily designated as Class I Federal areas consist of national parks exceeding 6,000 acres, wilderness areas and national memorial parks exceeding 5,000 acres, and all international parks that were in existence on August 7, 1977.” https://www.govinfo.gov/content/pkg/FR-2022-08-30/pdf/2022-18678.pdf,
Finding of Failure to Submit Regional Haze State Implementation Plans for the Second Planning Period, 87 Fed. Reg. 52856 (August 30, 2022) (to be codified at 40 C.F.R. pt. 52) (citing CAA §162(a)). The list of the 156 land areas to which the RHR applies is in 40 C.F.R. pt. 81, subpart D. Id. See also, EPA, https://www.epa.gov/visibility/regional-haze-program, which provides a map of the United States marking the sites protected by the RHR.
 US Code, https://uscode.house.gov/view.xhtml?path=/prelim@title42/chapter85/subchapter1&edition=prelim, 42 U.S.C. §7491 (a) (1) and (3) (B) (2022).
 Id. 42 U.S.C. §7491 (a) (3) (C) (2022).
 Id. 42 U.S.C. §7491 (c) (1) (2022).
 Id. 42 U.S.C. §7491 (c) (2) (2022).
 Id. 42 U.S.C. §7491 (c) (3) (2022).
 Id. 42 U.S.C. §7491 (b) (2) (A) (2022).
 American Corn Growers Association v. E.P.A., et al., 291 F.3d 1, 6 (D.C. App. 2002).
 Id. at 9.
40 C.F.R. §51.308 (d).
 Id. 40 C.F.R. §51.308 (d) (1) – (4).
 Id. 40 C.F.R. §51.308 (d) (1)(i)(A)(B).
 Id. 40 C.F.R. §51.308 (d) (1) (iv).
 Id. 40 C.F.R. §51.308 (d) (1) (iv).
 Id. 40 C.F.R. §51.308 (d) (2) (i).
 Id. 40 C.F.R. §51.308 (d) (2) (iii).
 Id. 40 C.F.R. §51.308 (d) (2) (iv). “Deciview is the unit of measurement on the deciview index scale for quantifying in a standard manner human perceptions of visibility.” ECFR, https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-51, 40 C.F.R. §51.301.
 Id. 40 C.F.R. §51.308 (d) (3).
 Id. 40 C.F.R. §51.308 (d) (3) (i).
 Id. 40 C.F.R. §51.308 (d) (3) (ii).
 Id. 40 C.F.R. §51.308 (d) (3) (iv).
 Id. 40 C.F.R. §51.308 (d) (3) (v) (A) – (G).
 Id. 40 C.F.R. §51.308 (d) (4).
 Id. 40 C.F. R. §51.308 (d) (4). Additional reporting requirements are listed in subsection (e) for the plan implementation of best available retrofit technology (BART). Id. 40 C.F. R. §51.308 (e). Progress reports and determinations of adequacy also are required. Id. 40 C.F.R. §51.308 (g) and (h).
 Id. 40 C.F.R. §51.308 (f).
 Protecting Visibility in National Parks and Scenic Areas, Amendments to the Regional Haze Rule, EPA, www.epa.gov/visibility/final-rulemaking-amendments-regulatory-requirements-state-regional-haze-plans
 Protection of Visibility: Amendments to Requirements for State Plans, 82 Fed. Reg. 3078 (January 10, 2017) (to be codified at 40 C.F.R. pts. 51 and 52).
 EPA, supra note 2, at 3. (This section lists the significant changes to the rule in 2017.)
 Protection of Visibility: Amendments to Requirements for State Plans, 82 Fed. Reg. 3078 (January 10, 2017) (to be codified at 40 C.F.R. pts. 51 and 52).
 Id. See also EPA, supra note 2, at 3-4.
 EPA, supra note 2, at 1.
 Id. at 52.
 Juan Carlos Rodriguez, 4 Takeaways From EPA’s Regional Haze Rule Guidance, www.law360.com (citing Draft Guidance on Progress Tracking Metrics, Long-term Strategies, Reasonable Progress Goals and Other Requirements for Regional Haze State Implementation Plans for the Second Implementation Period, (July 2016) at 73-74.)
 See id.
 Id. According to Mary Uhl, who serves as executive director of the Western States Air Resources Council, motor vehicle emissions constitute a significant source, but those emissions are subject to federal regulation. Id.
 See id. (Quoting Debra Jezouit, Esq.)
 EPA’s Decision to Revisit Aspects of the 2017 Regional Haze Rule Revisions, EPA, www.epa.gov/visibility/epas-decision-revisit-aspects-2017-regional-haze-rule-revisions.
Id. See also Rodriguez, supra, note 71.
 Protecting Visibility in National Parks and Scenic Areas, Amendments to the Regional Haze Rule, EPA, www.epa.gov/visibility/final-rulemaking-amendments-regulatory-requirements-state-regional-haze-plans.
 Id. (“‘The Western states have put down their marker that RAVI is a process that’s seen its time.’” Id. (Quoting Mary Uhl.))
George Cameron Coggins and Robert L. Glicksman, Interstate Pollution, 2 Pub. Nat. Resources L. §18:17 (2nd ed.) (February 2020) (citing North Carolina v. EPA, 531 F.3d 896 (D.C. Cir. 2008) and 71 Fed. Reg. 25304 (2006) wherein EPA denied petitions for reconsideration concerning the previous Clean Air Interstate Rule (CAIR)).
 Id. The CSAPR covers most of the eastern half of the United States, except for New England and Florida. See EPA, www3.epa.gov/airmarkets/progress/reports/program_basics_figures.html#figure2.
 Id. (Citing Environmental Protection Agency v. EME Homer City Generation, L.P., 134 S. Ct. 1584, 1609-10 (2014)).
 www.4cleanair.org Washington Update (February 8-14, 2020).
 www.4cleanair.org Washington Update (February 8-14, 2020).
 Id. (Linking to Complaint, Downwinders at Risk, et al. v. Wheeler, No. 1:20-cv-00349 (February 7, 2020) (citing State of Wisconsin, et al. v. Environmental Protection Agency, et al., 938 F.3d 303 (2019) and State of New York, et al. v. Environmental Protection Agency, 781 Fed.App’x *4 (2019)).
 Coggins and Glicksman, supra note 85.
EPA, https://www.epa.gov/system/files/documents/2021-08/epa-454-r-21-007.pdf. Technical Support Document for EPA’s Updated 2028 Regional Haze Modeling for Hawaii, Virgin Islands, and Alaska at 28 (August 13, 2021) (citing 40 C.F.R. §51.308(f)(1)(vi) and EPA, https://www.epa.gov/visibility/technical-guidance-tracking-visibility-progress-second-implementation-period-regional, Technical Guidance on Tracking Visibility Progress for the Second Implementation Period of the Regional Haze Program (December 28, 2018)).
 The Eastern Band of the Cherokee Nation is part of the SESARM RPO, however. EPA, supra note 29. Hopefully, this will encourage additional participation.
 See EPA, www3.epa.gov/airmarkets/progress/reports/index.html (Progress reports from 2018 show some improvement but only for the eastern states in the program.) See also EPA, www3.epa.gov/airmarkets/progress/reports/program_basics_figures.html#figure2.
“On April 13, 2022, a coalition of environmental groups sued EPA for failing to enforce a July 2021 deadline for states to submit regional haze implementation plans; litigation is ongoing.“ Environmental & Energy Law Program, https://eelp.law.harvard.edu/2018/04/regional-haze-rule/.
 See EPA, https://www.epa.gov/csapr/good-neighbor-plan-2015-ozone-naaqs (The EPA already has made recent, proposed additions to the CSAPR and Good Neighbor provisions. Id. “Under a consent decree, EPA must finalize the rule by December 15, 2022.” Environmental & Energy Law Program, https://eelp.law.harvard.edu/2017/09/cross-state-air-pollution-rule-and-section-126-petitions/.)
 EPA, supra, note 11.