PM2.5 NAAQS Lookahead: Revision of the Annual Standard is Imminent
Posted: January 9th, 2024
Authors: Dan D.
Another year has gone by and another lookahead article about potential lowering of the particulate matter less than 2.5 microns (PM2.5) National Ambient Air Quality Standard (NAAQS) is front and center. In last year’s lookahead article I wrote about the then very recent (January 6, 2023) publishing of the proposed rule to lower the PM2.5 annual NAAQS from 12 micrograms per cubic meter (µg/m3) to a level between 9 µg/m3 and 10 µg/m3. Since then, U.S. EPA has requested and received public comment, held public meetings, and a final rule was sent to the White House Office of Management and Budget (OMB) for pre-publication on September 22, 2023. OMB review typically takes 90 days. However, for controversial, high-profile rules such as this one, the process can take longer to allow for stakeholders to meet with OMB and United States Environmental Protection Agency (U.S. EPA). ALL4 has been directly involved in some of these meetings and has provided technical support to trade organizations for others. One of the requests ALL4 has been involved in supporting is a delayed effective date for a the final PM2.5 NAAQS rule to allow for an implementation period. A delayed effective date would allow time for air quality modeling policy and guidance to be updated and refined to incorporate less conservative and more accurate modeling methods to be developed. As presented in my 2023 look ahead article, a major concern with a lowered annual PM2.5 NAAQS is the difficulty with air quality modeling demonstrations which require the inclusion of background concentrations from ambient monitoring stations where many of those PM2.5 background concentrations across the country are approaching the proposed lower PM2.5 annual NAAQS. This leaves little headroom for new projects and industrial growth. While there is still a question where the revised standard will be set, it is very likely that it will be lowered.
As I write this article in the first week of 2024 the final rule is still at OMB and on January 2, 2024, U.S. EPA filled a motion with the U.S. Court of Appeals for the District of Columbia to extend abeyance of the lawsuit brought by the State of California, the American Lung Association, and the Center for Biological Diversity against the 2020 rule that retained the NAAQS until January 30, 2024. The final reconsideration rule may make petitioners’ claims moot. This motion gives U.S. EPA until the end of the January 2024 to finalize the PM2.5 NAAQS rule and then it can take an additional one to two weeks for the final rule to be published in the Federal Register. Based on this timeline I expect a final published rule to be released in mid-February 2024.
A final, lowered PM2.5 NAAQS (without a delayed effective date) will immediately impact air permit applications that contain PM2.5 NAAQS air quality modeling demonstrations. Any air permit applicant that has not received a final permit that has a modeling demonstration included may need to re-submit the annual PM2.5 NAAQS air quality modeling demonstration to model below a revised lowered annual PM2.5 NAAQS if they haven’t already. One nuance to be aware of is whether you are conducting a modeling demonstration to meet a state or federal requirement. If your modeling demonstration is to meet a state requirement, in some cases the state you are located in will need to first adopt the lowered standard into the state rules which means you could have more time (although the public could object to the state issuing a permit based on the old NAAQS). If your modeling demonstration is to meet a federal requirement such as the Prevention of Significant Deterioration (PSD) permitting program the new PM2.5 NAAQS will be immediate upon publishing of the final rule.
The second major impact on the regulated community will take longer to become effective. States are required to propose updated attainment/nonattainment designations to U.S. EPA based on ambient monitoring data and U.S. EPA is required to finalize the updated designations within two years of a final revised PM2.5 NAAQS, which would put updated designations in February of 2026. There is the potential for a substantial increase in PM2.5 nonattainment areas, which will trigger more stringent nonattainment new source review (NNSR) permitting requirements, including Lowest Achievable Emissions Rate (LAER) requirements and requirements to purchase PM2.5 emissions reduction credits (ERCs) to offset project emissions. PM2.5 NNSR permitting is also complicated by the fact that there are potentially four PM2.5 precursors that must be considered: oxides of nitrogen (NOX), sulfur dioxide (SO2), ammonia (NH3), and volatile organic compounds (VOC). However, the NNSR permitting requirements won’t kick in until 2026 so there is still time to go through the permitting process and receive a permit before these more stringent permitting requirements take effect.
ALL4 has substantial experience in PM2.5 air quality modeling demonstrations and NNSR PM2.5 permitting. For more information about how a lowered PM2.5 NAAQS will affect your facility and how ALL4 can help check out ALL4’s PM2.5 NAAQS Resource webpage or contact Dan Dix at ddix@all4inc.com or (610) 422-1118.
