On March 6, 2024, EPA published its final rule lowering the primary annual National Ambient Air Quality Standards (“NAAQS”) for fine particulate matter (“PM2.5”) to 9.0 micrograms per cubic meter (“µg/m3”). The new, more stringent standard replaces the prior primary annual PM2.5 NAAQS if 12.0 µg/m3, which were established in 2012. In support of lowering these health-based standards, EPA cited to recent studies suggesting that adverse health effects from exposure to PM2.5 are occurring at concentrations allowed by the 2012 standard, with additional studies demonstrating improvements in public health, including reductions in mortality, following reductions in PM2.5 in areas with air quality below 12.0 µg/m3. The new 9.0 µg/m3 standard is within the range recommended by the Clean Air Scientific Advisory Committee, which had recommended lowering the standard between 8-10 µg/m3.
The rule will become effective on May 6, 2024, 60 days after it was published in the Federal Register. After the rule becomes effective, EPA will begin the process of implementing the revised PM2.5 NAAQS. Within two years after the effective date, EPA must designate areas as meeting (attainment areas) or not meeting (nonattainment areas) the new PM2.5 NAAQS considering the most recent air quality monitoring data and input from states. Within three years after the effective date, states must submit State Implementation Plan revisions to show they have the basic air quality management program components in place to implement the revised PM2.5 NAAQS. Areas designated as nonattainment will then have planning obligations to demonstrate attainment and must submit nonattainment area State Implementation Plans within 18 months after the effective date of the designations outlining how they will meet the new standard within six years. Under this timeline, the earliest that states would likely need to come into attainment with the revised PM2.5 NAAQS is 2032.
Notwithstanding the longer timeline for states to come into compliance with the rule, the revised PM2.5 NAAQS will immediately begin applying to stationary source permitting under the New Source Review (“NSR”) construction permitting program. States will use the attainment designations for the prior PM2.5 NAAQS to determine whether a source must pursue Prevention of Significant Deterioration (“PSD”) permitting for attainment areas or Nonattainment New Source Review (“NNSR”) for nonattainment areas. Applicants will need to demonstrate that their new or modified major source will not cause or contribute to a violation of the new PM2.5 NAAQS.
After EPA makes its attainment designations, certain areas that are currently designated as attainment areas may be reclassified as nonattainment areas, with the result that new or modified major sources in those areas would become subject to more onerous NNSR permitting requirements, including obligations to comply with the lowest achievable emission rate (“LAER”) and obtain emissions offsets. Based on air monitoring data collected from 2020 to 2022, EPA has estimated that 119 counties do not currently meet the 9.0 µg/m3 standard. Taking into account anticipated reductions in PM2.5 emissions from federal regulations, EPA has projected that 52 counties (half of which are in California) will not meet the revised PM2.5 NAAQS by 2032. NNSR permitting for new major sources or major modifications to existing sources will be challenging in these projected nonattainment areas, which may drive industry to move forward with projects in areas currently designated as attainment before EPA designates them as nonattainment areas in the future.
In the final rule, EPA also revised the PM2.5 monitoring network design criteria to include an environmental justice factor that accounts for the proximity of populations at increased risk of PM2.5-related health effects to air pollution sources of concern. EPA currently determines how many monitors, at minimum, are required in an area based on two factors: the population of the area, as well as the expected air quality status of the area relative to the NAAQS. Under the final rule, areas with additional required State or Local Air Monitoring Stations (“SLAMS”), a monitoring station is to be sited in an at-risk community where there are anticipated effects from sources in the area. This change is consistent with Executive Orders issued by President Biden relating to environmental justice.
The final rule is sure to be challenged through petitions for reconsideration submitted to EPA and in lawsuits filed in the U.S. Court of Appeals for the D.C. Circuit which, in each case, must be submitted within 60 days the final rule is published in the Federal Register. Continue to follow our blog for further updates regarding implementation and litigation of this rule.
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