The Nickel Report

In response to judicial remand of its Cross-State Air Pollution Rule (CSAPR) Update, EPA published a revised CSAPR Update – the latest of EPA’s interstate transport rules using its CSAPR methodology – at the end of April 2021, slashing ozone-season budgets for emissions of nitrogen oxides (NOx) for a dozen states.[1]  By the end of the 60-day period for filing petitions for judicial review on June 29, a single petition for judicial review had been filed in the US Court of Appeals for the DC Circuit.

On October 30, 2020, EPA published in the Federal Register a proposed rule to revise its 2016 Cross-State Air Pollution Rule Update (the CSAPR Update) to further reduce interstate air pollution from 12 upwind states. EPA is proposing this revision pursuant to its authority under the Clean Air Act’s “Good Neighbor” provision (section 110(a)(2)(D)(i)(l)), which requires upwind states to prevent sources located within their borders from contributing significantly to nonattainment or interfering with maintenance, of the national ambient air quality standards (NAAQS) in downwind states.

As I have reported previously, the US Court of Appeals for the DC Circuit issued a significant decision in September 2019 on EPA’s implementation of the so-called “Good Neighbor Provision” of the federal Clean Air Act (CAA). That is the CAA’s principal provision addressing what is often termed “interstate transport,” the physical process in which emissions from cars, trucks, factories, power plants, and myriad other sources—and the resulting air pollution—are carried by prevailing winds across state borders. The main purpose of the Good Neighbor Provision (section 110(a)(2)(D)(i)(I) of the CAA) is to prevent “significant contribution” by “upwind” states’ emissions to violations of national ambient air quality standards (NAAQS) in “downwind” states. Although states have the principal responsibility to implement this provision, EPA periodically has invoked its CAA authority to impose requirements to curb interstate transport when it determines upwind states have not adopted adequate controls.

A previous post, EPA Makes Room for State Flexibility in Addressing “Interstate Transport” Under the Clean Air Act, discussed the evolving policy of the US Environmental Protection Agency (EPA) regarding approval of state plans—required under the “Good Neighbor Provision” of the federal Clean Air Act—addressing “interstate transport” of air pollution. That article reviewed a series of guidance documents EPA issued in 2018 to allow states flexibility in addressing wind-borne emissions that can contribute to ground-level ozone pollution in other states located downwind. At stake are not only downwind states’ air quality objectives but the prospect of expensive additional emission controls on upwind states’ manufacturing facilities and power plants.

One of EPA’s 2018 guidance documents addresses the seemingly technical question of what “contribution threshold” to apply. That term refers to the quantity—measured in parts per billion (ppb) of ozone in the air at ground level—below which an upwind state’s impact on a downwind state’s ozone concentrations is small enough that any contribution would be considered essentially de minimis. Generally, a state will want its emission contributions to be deemed low enough that it would be clear that its emission sources would not need new control requirements.

As we have discussed previously, the federal Clean Air Act (CAA) addresses what is often termed “interstate transport.” That is the phenomenon in which emissions from factories, power plants, motor vehicles and many other emission sources are transported by prevailing winds across state lines, sometimes over great distances. The CAA looks to states, first and foremost, to include control measures in implementation plans to reduce emissions that travel into other states. The statutory objective is to prohibit “significant contributions” by upwind states to violations of national ambient air quality standards (NAAQS) in downwind states. Although states have primary responsibility, EPA sometimes has invoked its CAA authority to establish federally enforceable requirements to address significant contributions when it concludes upwind states have not taken sufficient steps. In 2016, EPA adopted its most recent set of regulatory interstate transport controls in a rulemaking action called the “Cross-State Air Pollution Rule Update”—or the “CSAPR Update” for short. On September 13, the US Court of Appeals for the DC Circuit issued a decision in closely-watched litigation involving challenges to the CSAPR Update. (The case is Wisconsin v. EPA, No. 16-1406.) While upholding this EPA regulation in most respects, the court ruled in favor of a challenge that concerns the timing of upwind-state emission controls.

The phrase “interstate transport” conjures images of planes, trains and trucks carrying people and goods cross-country. But, under the federal Clean Air Act (CAA), the term is often used to refer to interstate air pollution—emissions from factories, power plants, motor vehicles, refineries and other sources that are transported by prevailing winds across state lines, sometimes over hundreds of miles. The interstate transport phenomenon often has posed for the US Environmental Protection Agency (EPA) what the Supreme Court has called “a thorny causation problem: How should EPA allocate among multiple contributing upwind States responsibility for a downwind State’s excess pollution?” EPA v. EME Homer City Generation, L.P., 134 S. Ct. 1584, 1604 (2014). EPA’s efforts to address this issue have yielded, over the last two decades, a series of complex federal regulatory programs imposing increasingly stringent controls on emissions in most states in the eastern half of the country—first the “NOx SIP Call” rule in 1998, then the Clean Air Interstate Rule in 2005, followed by the Cross-State Air Pollution Rule (CSAPR) in 2011 and, most recently, the 2016 “CSAPR Update” rule. Now, however, EPA, while vigorously defending the CSAPR Update rule against pending litigation challenges, is signaling a fresh approach for potential future interstate transport regulation, an approach that may involve greater deference to states’ analyses and determinations and that may eschew additional broad regulatory mandates imposed by EPA.