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On December 6, 2018, EPA published the final 2015 Ozone NAAQS Implementation Plan, effective February 4, 2019. The rule provides state implementation plan (SIP) requirements for nonattainment areas and the ozone transport region with respect to the 2015 Ozone NAAQS. While the rule outlines the requirements for state, local, and tribal air agencies with respect to SIPs, the requirements will impact regulated sources of volatile organic compounds (VOC) and nitrogen oxides (NOx).

The 2015 Ozone NAAQS Implementation Plan is largely an update of the 2008 Ozone NAAQS Implementation Plan with a few key changes and is codified at 40 CFR Part 51 Subpart CC. Note the rule does not include the proposed revocation of the 2008 Ozone NAAQS or anti-backsliding requirements as EPA is still evaluating comments submitted on those items. The EPA will address the proposed revocation of the 2008 Ozone NAAQS and anti-backsliding requirements in a future rulemaking.

Rule elements remaining largely the same as the 2008 Ozone NAAQS Implementation Plan include:

  • State Implementation Plan (SIP) submittal deadlines, format, and content
  • Requirements for nonattainment area re-designation for those initially designated as attainment areas
  • Eligibility determinations for 1-year attainment date extensions
  • Modeling and attainment demonstration requirements
  • Reasonable Further Progress (RFP) requirements
  • Requirements for Reasonably Available Control Technology (RACT) and Reasonably Available Control Measures (RACM)
  • NOX exemption provisions
  • Nonattainment New Source Review (NNSR) requirements
  • Ambient monitoring requirements
  • Ozone Transport Region (OTR) requirements
  • Fees for severe and extreme nonattainment areas failing to attain the NAAQS
  • International transport

Rule elements representing changes or additions to the 2008 Ozone NAAQS Implementation Plan include:

  • Addition of RPF requirements for periodic Milestone Compliance Demonstration (MCD) submittals by agencies to EPA
  • New RACT SIP revision submittal and implementation deadlines for area re-classifications and issuance of new Control Techniques Guidelines (CTGs) by EPA
  • RACM consideration of intrastate transport may require
    • The affected agency to consider impacts on the nonattainment area from that state's upwind attainment area sources' emissions
    • Control measures on upwind attainment area sources to allow downwind nonattainment areas to achieve attainment
  • Allowance of Interprecursor Trading (IPT) for ozone offsets - An agency interested in establishing IPT must submit a plan of IPT provisions and supporting modeling used to develop the area-specific IPT ratios or agree to use default IPT ratios.
  • Update to the emissions inventory requirements to include the same Air Emissions Reporting Requirement (AERR) thresholds for NOx as for VOC for serious, severe, and extreme nonattainment areas (other requirements for emissions inventories and emission statements remain the same as the 2008 Ozone NAAQS Implementation Plan)

Finally, while the rule did not include specific regulatory provisions, it does include additional guidance on policies for handling emissions from wildfires, transportation conformity, and contingency measures for areas failing to meet a milestone or attainment date, background ozone, and achieving emissions reductions.