Environmental Permitting

Cross-State Air Pollution Revisited – History and Purpose

A Brief History
The CSAPR was finalized on July 6, 2011, as a replacement for the 2005 Clean Air Interstate Rule (CAIR), which the U.S. District Court of Appeal for the District of Columbia ruled in 2008 had “more than several fatal flaws.”

Following the CAIR decision, the EPA implemented the CSAPR and again found itself in court in the case EME Homer City Generation, L.P. v. EPA, which found that while the CSAPR lawfully sets pollution threshold levels and addresses upwind exceedances contributing to downwind nonattainment, the court also found the CSAPR forces states to control pollution below set thresholds and that EPA’s federal implementation plan (FIP) first approach was “incompatible with the basic text and structure of the Clean Air Act.”

This decision effectively vacated the CSAPR and halted the January 2012 implementation of the rule. However, the EPA then appealed the case to the U.S. Supreme Court. In its decision, the nation’s highest court reinstated the CSAPR in a 6-to-2 decision (Justice Alito did not participate) ruling that the EPA lawfully applied the CSAPR to reduce emissions and that the agency’s approach was acceptable under the Clean Air Act (CAA).


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The Overriding Purpose
Both the CAIR and the CSAPR have the same basic purpose: to “require states to significantly improve air quality by reducing power plant emissions that cross state lines and contribute to ozone and fine particle pollution in other states.” The premise for this purpose is CAA’s Good Neighbor Provision at Section 110(a)(2)(D)(i)(I), which requires mandatory state implementation plans to:
“(D) contain adequate provisions—
(i) prohibiting, consistent with the provisions of this subchapter, any source or other type of emissions activity within the State from emitting any air pollutant in amounts which will—
               (I) contribute significantly to nonattainment in, or interfere with maintenance by, any other State with respect to any such national primary or secondary ambient air quality   standard,…”


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Sounds simple enough, but in fact achieving this requirement has proven to be not only contentious but also complex. During recent stakeholder meetings about moving forward with the CSAPR, the EPA found a very broad range of opinions among attendees regarding key meeting topics, such as roles and responsibilities, proportionality (i.e., how to approach calculating upwind/downwind proportionality of emissions), costs to attain National Ambient Air Quality Standards (NAAQSs) for both upwind and downwind states, and technical issues regarding modeling to determine state obligations. In addition, the EPA will keep communications open moving forward and has identified the following potential guiding principles for ongoing discussion:

  • Speed,
  • Fairness,
  • Transparency, and
  • Legal soundness.

The CSAPR, as promulgated, covers power plants in 28 states and requires annual reductions of sulfur dioxide (SO2) and annual emissions of nitrogen oxide (NOx) and/or ozone season NOx emissions to meet the limits set in 1997 for ozone and fine particles and in 2006 for fine particles according to the NAAQS. A supplemental rulemaking in late 2011 requires five states—Iowa, Michigan, Missouri, Oklahoma, and Wisconsin—to meet summertime NOx reductions under the CSAPR ozone season control program. Not every state must meet all reductions although most do. Tomorrow, we will look at the current state of power plant emissions and the benefits and costs of the CSAPR.