Regulatory Developments, Special Topics in Environmental Management

EPA Issues Implementation Requirements for 2015 Ozone NAAQS

After grumbling that it intended to resist implementing the revised National Ambient Air Quality Standards (NAAQS) for ozone it issued in 2015, in August 2018, the EPA informed a federal court that it had decided to uphold and defend the NAAQS as they had been promulgated. That decision set in motion the Agency’s responsibility to issue final state implementation plan (SIP) requirements for the 2015 NAAQS. Those requirements have now been published in a final rule (December 6, 2018, Federal Register (FR)).

air emissions, pollution

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The rule applies to areas in nonattainment with the 2015 NAAQS and nonattainment areas in the Ozone Transport Region ((OTR), comprising 13 Eastern states from Virginia north to Maine plus the District of Columbia). States now have direction and deadlines for submitting SIPs that show how they will bring nonattainment areas into attainment with the 2015 NAAQS.

Cost Disagreements

The Agency’s 2015 final rule (October 1, 2015, FR) revised the NAAQS from 75 parts per billion (ppb) to 70 ppb to ensure the protection of public health and welfare. The revision sparked considerable debate about the cost that would be imposed on the U.S. economy. When the NAAQSs were issued, the EPA estimated the cost at about $1.5 billion. Industry viewed this estimate as grossly inaccurate and came forward with numbers ranging from $90 billion to $1 trillion. Those estimates were highlighted in many lawsuits challenging the rule. Along the way, the EPA announced that it would reconsider certain methods used to determine nonattainment, including consideration of background and international ozone.

Components of the Rule

The Agency now says the final implementation rule is largely an update to the implementing regulations previously promulgated for the 2008 ozone NAAQS.

“We are retaining without significant revision the majority of those provisions to implement the 2015 ozone NAAQS,” states the EPA.

The final rule addresses a range of nonattainment area and OTR SIP requirements for the 2015 ozone NAAQS, including requirements for:

  • Attainment demonstrations
  • Milestone compliance demonstrations to address reasonable further progress requirements;
  • Planning and implementation deadlines for reasonably available control technology (RACT);
  • Reasonably available control measures (RACMs);
  • Consideration of pollution sources within a state but outside a nonattainment area for purposes of attainment planning;
  • Optional ozone NAAQS trading provisions for pollutants that react to form ozone, which would allow either volatile organic compounds (VOCs) or nitrogen oxides (NOx) emissions reductions to satisfy nonattainment New Source Review permitting emissions offset requirements for VOC or NOx emissions increases;
  • The timing of required SIP submissions and compliance with emissions control measures in the SIP; and
  • Emissions inventories and emissions statements.

The rule states that the EPA is maintaining its existing approach to evaluating potential impacts of international transport of ozone and ozone precursors under the Clean Air Act (CAA) Section 179B. The EPA also clarifies that a demonstration prepared under CAA Section 179B could consider emissions emanating from North American or intercontinental sources and is not restricted to areas adjoining international borders.


The rule includes multiple deadlines for states, including:

  • 2 years from the effective date of nonattainment designations for states with nonattainment areas to submit SIP revisions addressing emissions inventories;
  • 3 years from the effective date of nonattainment designations to submit SIP revisions addressing 15 percent rate of progress (ROP) plans; and
  • 4 years from the effective date of nonattainment designations to submit SIP revisions addressing 3 percent per year reasonable further progress (RFP) plans.

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