EPA Proposes to Strengthen the Ozone NAAQS



On September 19, 2009, the U.S. EPA Administrator Lisa Jackson announced that EPA would take rulemaking action to reconsider the 2008 primary and secondary ozone national ambient air quality standards (NAAQS) of 0.075 parts per million (ppm), that was promulgated in March 2008.  On January 6, 2010, Administrator Jackson announced that upon reconsideration of EPA’s original scientific advisory committee recommendations used to establish the March 2008 standards, EPA was proposing to further lower the primary and secondary ozone standards to ensure adequate protection of public health and the environment.  The range of ozone standard under consideration in the January 2010 proposal represents a significant strengthening of the ozone NAAQS that may ultimately result in major portions of the U.S. being designated as nonattainment.

Why the Continued Focus on Ozone?

For decades, scientific evidence has indicated that adverse public health effects occur as a result of exposure to significant concentrations of ground-level ozone, particularly in children, the elderly, and adults with lung disease.  In addition, cumulative ozone exposure can damage sensitive vegetation, reducing growth and increasing susceptibility to disease.  Ongoing research regarding human health and ecological impacts indicates that lower ozone levels than first recognized have deleterious health effects, particularly on sensitive populations.

Section 109(b)(1) of the Clean Air Act (CAA)requires that primary NAAQS be established with an adequate margin of safety to protect human health and Section 109(b)(2) requires secondary NAAQS  to protect the public welfare from any known or anticipated adverse effects.  The primary NAAQS for any criteria pollutant, such as ozone, must be set without regard to costs to attain and maintain compliance (supported by the Supreme Court’s decision in Whitman v. American Trucking, 531 U.S. 457 - 2001); however, the anticipated costs and benefits of such standards are routinely evaluated when a NAAQS is established.

Long and Winding Path of the Ozone Standards

As scientific knowledge regarding the effects of ozone has progressed, EPA has set traffic jamprogressively more stringent standards.  In 1971, EPA established the first ozone standard at 0.08 ppm, 1 hour average, which was revised to 0.12 ppm, 1-hour average, in1978.  In 1997, EPA strengthened the standard, reducing the level to a 0.08 ppm, 8-hour average (effectively, a 0.084 ppm standard, when considering rounding). Nonattainment designations and the basic implementation rule for the 1997 standard were finalized in 2004 resulting in the designations currently in effect.  A map depicting current ozone nonattainment areas is presented in Figure 1 above.

In March 2008, both the primary and secondary ozone standards were reduced to 0.075 ppm, based on an 8-hr average.  There was sharp disagreement by many in the scientific community and by public health advocates who believed that the standard did not comport with the level of stringency mandated by the CAA since EPA’s Clean Air Scientific Advisory Committee (CASAC) clearly indicated adverse impacts at lower levels, as seen in Figure 2 above.

EPA was poised to promulgate nonattainment designations under the March 2008 NAAQS in December 2009.  These nonattainment designations would have become effective by March 12, 2010, impacting a considerable amount of the U.S. currently “in attainment” with the previous ozone NAAQS.  A map depicting counties in the U.S. that have monitors indicating violation of the March 2008 standard is presented above.  While the 322 counties shown in the figure above is substantial, the number of counties that would have actually been designated nonattainment would have been considerably higher.  This would result from EPA guidance, issued on December 4, 2008, which requires not only counties with a monitor indicating violation of the standard be designated nonattainment, but also one or more counties near violating monitors be included in the nonattainment area designation (typically consistent with counties grouped under metropolitan statistical areas).  

On September 19, 2009, EPA announced that it would take rulemaking action to reconsider the 2008 primary and secondary NAAQS, and on January 19, 2010, EPA said that it would delay final designations for the 2008 NAAQS until March 12, 2011 to allow adequate time for reconsideration and possible revision of the 2008 NAAQS.

Proposed Revised Standard 

On January 19, 2010, EPA published in the Federal Register the following proposed revisions to the ozone standards:

  • A primary ozone NAAQS in the range of 0.060 to 0.070 ppm, based on the 3-year average of the fourth-highest daily maximum 8-hour average ozone concentrations
  • A secondary NAAQS in the range of 7 to 15 ppm ozone, with a “W126” averaging   time, where the W126 uses a sigmoidal weighting methodology to assign a weight to each hourly ozone concentration within the 12-hour daylight perio (8 am to 8 pm)

As previously indicated, EPA did not propose a specific value for either the primary or secondary NAAQS; however, EPA has requested comments as to what the specific values should be within the ranges contained in the proposed rule.

Proposed Timeline

According to EPA, the planned promulgation and implementation of the revised ozone standards is as follows:

  • August 31, 2010 – final standards are issued
  • January 2011 – states make recommendations for areas to be designated attainment, nonattainment, or unclassifiable
  • July 2011 – EPA makes final designations under an accelerated designation schedule
  • August 2011 – designations become effective December 2013 – State Implementation Plans (SIPs) are due to EPA
  • December 2013 - State Implementation Plans (SIPs) are due to EPA
  • 2014 to 2031 – states are required to meet the primary standard, with deadlines depending upon the severity of the problem

It should be noted that EPA is considering delaying designations and the subsequent implementation milestones for the secondary ozone standard until two years after promulgation, the maximum time allowed under the Clean Air Act.

More Areas Headed Toward Nonattainment

The estimated number of counties in the U.S. with monitoring data that currently exceeds the proposed 0.060 to 0.070 ppm 8-hour ozone NAAQS levels ranges from 515 to 650 counties, as shown in Figure 3 above.

A number of states across the U.S. will be dramatically impacted by a new primary ozone standard, especially states that are in attainment with current standards or have only a few counties violating existing standards.  For instance, the entire state of Florida is in attainment with the 1997 ozone standards and would only have a few counties exceeding the 2008 standard.  However, many more counties would exceed the proposed ozone standard even at the upper end of the proposed range (0.070 ppm).  According to EPA, it is unclear how many areas will not comply with the secondary standard because the “W126” standard is an entirely new “form” of air quality standard (i.e., averaging period and method).

According to EPA staff currently working on the revised ozone standards, due to past legal precedent, EPA will not consider allowing states to develop “Early Action Plans” to avoid nonattainment designations in exchange for early commitments to reduce ozone.

Although the map presented to the right depicts a significant increase in the number of counties designated as nonattainment, this only partially conveys the impact of the standard.  As was the case under the 2008 standard, future EPA designation guidance will likely require that counties meeting future-specified criteria that are near violating monitors also be considered part of a nonattainment area, thus drastically increasing the number of counties that will be designated nonattainment.

Another aspect of the proliferation of nonattainment areas across the country is that the current monitoring network is inadequate to determine attainment status in areas that do not have nearby monitoring sites.  If a standard of 0.070 ppm or lower is promulgated, EPA will likely require additional monitoring sites to enhance the existing monitoring network. These additional monitoring sites could potentially detect further violations of the standards.  Many such areas will likely be designated as “unclassifiable” and avoid immediate impacts under the standards.  However, once new monitoring sites have been operating the full three years required to assess compliance with the new ozone standard, many more counties throughout the country may be designated as nonattainment.  EPA has not developed preliminary plans regarding any of these “implementation” related issues, so there will be considerable uncertainty, until the revised standards are promulgated later this year.

“Backstop” Ozone Standard

Although it appears likely that EPA will promulgate lower primary and secondary ozone NAAQS later this year, establishing the standards will be contentious.  It is quite possible that revision of the 2008 ozone standards could be delayed.  To offset the possibility that implementation of ozone standards more protective than the 1997 standards of 0.08 ppm will be delayed if the current reconsideration of the 2008 standard encounters delays, EPA has left in place the 2008 ozone standard of 0.075 ppm.  If the current rulemaking effort to lower the standards is delayed, EPA intends to promulgate final designations under the 2008 standard by December 12, 2010 with an effective date of March 12, 2011.  Under either scenario, the standards are being lowered, and additional nonattainment areas will be designated.

Short and Long-Term Impacts to Industry

EPA, states, and industry are anticipating long-term challenges to meeting lower ozone standards.  Although EPA may promulgate significant federal regulations with the intent of reducing ozone concentrations within the next few years (such as a revised Clean Air Interstate Rule), many states will face difficult decisions regarding the stringency of existing state regulations including reasonably available control technology (RACT) requirements in ozone nonattainment areas.  Although reduction strategies in specific non-attainment areas are speculative at this time, it appears likely that many industrial facilities located in new nonattainment areas will eventually face tougher air pollution control requirements.

A more immediate impact to industry of upcoming nonattainment designations will be imposition of nonattainment new source review (NNSR) for new major sources and major modifications for ozone precursors, volatile organic compounds (VOC), and oxides of nitrogen (NOx).  Depending on the “severity” of the nonattainment designation, NNSR will be triggered at different thresholds.  In marginal and moderate areas, NNSR is triggered for new sources at 100 tons per year (tpy) and for existing sources at 40 tpy or less.  Both of these thresholds are lower as the severity of the nonattainment designation increases.  Once revised ozone designations are finalized (whether EPA designates under the 2008 standards or under the proposed ozone standards), NNSR will be triggered for any qualifying projects immediately upon the effective date of ozone nonattainment designations.  Qualifying projects for which “complete” air quality construction applications have been submitted to permitting agencies, but for which final permits have not yet been issued, will be subject to NNSR requirements including construction and operation of lowest achievable emission rate (LAER) technology and obtaining emissions offsets.

In addition to significant impacts under the New Source Review program, the new ozone standard will impact the Title V program.  Typically triggered in attainment areas at a potential to emit (PTE) of 100 tpy of VOC or NOx, if standards more stringent than the 2008 ozone standard are promulgated, the likelihood of areas being designated at “higher” severity levels increases.  Title V applicability thresholds in higher severity nonattainment areas can be 50 tpy or less, depending upon severity.

There are a number of uncertainties regarding the eventual outcome and impacts of EPA’s current rulemaking efforts. However, if the ozone standards are reduced to levels currently under consideration (even the high end of the ranges), the number of areas of the country likely to become nonattainment will increase dramatically and will have significant implications on pollution control requirements and permitting for industry for many years to come.