On December 21, 2024, the Pennsylvania Department of Environmental Protection (PADEP) proposed recommendations for non-attainment areas (areas not meeting the revised annual health-based Nation Ambient Air Quality Standards [NAAQS]) for fine particulate (PM2.5) in Pennsylvania. These recommendations include nonattainment areas that are geographically broader than monitored non-attainment areas. These recommendations by the PADEP are in response to the NAAQS revisions issued by the United States Environmental Protection Agency (EPA) in February 2024. In these revisions, the EPA changed the annual PM2.5 standard from 12 micrograms per cubic meter of air (μg/m3) to 9.0 μg/m3, meaning that any area that does not have an annual concentration at or below 9.0 μg/m3, averaged over a 3-year period, are now classified as non-attainment area under the revised NAAQS. Note that under this proposed change there were no changes made to any other particulate NAAQS, including, primary 24-hour PM2.5 and PM10 standards and secondary PM2.5 and PM10 standards.
The EPA establishes ambient air quality limits on PM2.5 due to the health and environmental risks associated with fine particles. Health risks associated with PM2.5 include aggravation of respiratory and cardiovascular disease, lung disease, decreased lung function, asthma attacks, respiratory symptoms such as difficulty breathing, chronic bronchitis, and cardiovascular problems such as heart attacks and arrhythmia. Environmental risks include reduced visibility or haze, damage caused by soot, and settling damage. Additionally, components of PM2.5, such as nitrates and sulfates contribute to the formation of acid rain. Acid rain causes damage to lakes, rivers, and streams, as well as causing erosion to buildings, monuments, and cars.
Once the EPA finalizes its new PM2.5 standards, each state is required to submit recommendations for attainment/nonattainment areas no later than one year after the EPA published new or revised NAAQS. The EPA has defined criteria that states should examine to recommend nonattainment boundaries. These factors include air quality data, emission and emissions-related data, meteorology, geography and topography, and jurisdictional boundaries. The PADEP’s recommendations for nonattainment areas are based on 2021-2023 air quality monitoring data, whereas the EPA designation will most likely be based on 2022-2024 air quality monitoring data.
Based on their analysis, PADEP is proposing that the following areas be designated as nonattainment areas; Allegheny County, the Greater Philadelphia Area (consisting of Delaware, Montgomery, and Philadelphia Countries), Harrisburg-Carlisle-York area (Cumberland, Dauphin, and York counties), and Lancaster County. Notably, there are three nonattainment regions in Pennsylvania: Southwest Pennsylvania, Eastern Pennsylvania, and Southcentral Pennsylvania. All other counties and regions in Pennsylvania were recommended to be classified as either unclassifiable or attainment
In Southwestern Pennsylvania, PADEP is proposing that the nonattainment areas for the primary annual PM2.5 standard be limited to Allegheny County. The PM2.5 monitors in Allegheny County had a 2023 annual design value over the revised primary annual standard. PADEP found that these high PM2.5 readings were local to Allegheny County when looking at monitors throughout the region. This is likely due to both wind patterns and the urban designation of Allegheny County. Therefore, due to the PM2.5 exceedances and the localization of these exceedances, PADEP is recommending that only Allegheny County be classified as a nonattainment area.
In Eastern Pennsylvania, PADEP is proposing that the nonattainment areas for the primary annual PM2.5 standards be limited to Delaware, Montgomery, and Philadelphia Counties. In Philadelphia County, similarly to Allegheny County, the PM2.5 monitors showed greater concentrations than other regional concentrations in the same range. Additionally, it was found that Delaware Couty had the highest NOX and VOC point source emissions and PM2.5 emission density after Philadelphia County. In this region, most PM2.5 and precursor (SO2, NOX, VOC) point source emissions were located in Philadelphia, Delaware, and Montgomery Counties. Point sources emissions were much lower in Chester and Bucks Counties. Therefore, though the Delaware and Montgomery monitors were showing attainment for the primary annual PM2.5 standard, due to possible emission impacts, they are proposed to be classified alongside Philadelphia County as nonattainment.
In Southcentral Pennsylvania, there are two areas proposed as nonattainment. The proposed nonattainment areas are the Harrisburg-Carlisle-York area (consisting of Dauphin, Cumberland, and York Countries) and Lancaster County. The PM2.5 monitors in Dauphin and York Countries were shown to have a 2023 annual design value that exceeds the 2024 primary annual PM2.5 standard. These readings were found to be local to the Harrisburg and York Monitors. There are also several point sources along the Cumberland/Dauphin County Border. Thus, PADEP is proposing to designate Dauphin and York Counties as nonattainment due to their monitoring data and also designated Cumberland County as nonattainment due to possible emission impacts, particularly concerning those point sources on the county border.
One of the monitors in Lancaster County (Lancaster Downwind) saw greater concentrations than other regional concentrations in the same range. Additionally, Lancaster County has the largest ammonia area source emission density (ton/mi2) in Pennsylvania. This is important because excess ammonia can form ammonium nitrate, a significant component of PM2.5. Wind profiles have shown that this issue is local to the Lancaster Downwind Monitor. Therefore, PADEP is proposing to designate Lancaster County as a nonattainment area in Southcentral Pennsylvania.
The Department will provide the opportunity to hold three public hearings, if requested, to receive comments on the proposals. There is a public hearing scheduled for January 21-23rd, 2025.
The Department must receive comments no later than January 24, 2025. Commentators are encouraged to submit comments using the Department’s eComment system or by e-mail.
Final designations will be made and published by the EPA by February 2026. Once the final designations are made, states will have 18 months to complete State Implementation Plans (SIP) revisions. These revised SIPs will be due to the EPA by August 2027.
If you would like to discuss these new PM2.5 proposed designations and how they may impact your facility, please contact Trinity’s Philadelphia or Pittsburgh offices or call 908.432.8001 or 724.442.6808.
