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Allegheny County PM2.5 Levels Below Federal Standard but the Future is Still Hazy

Updated: Apr 16

The U.S. Environmental Protection Agency (EPA) in September announced that the agency intends to make a Clean Data Determination regarding levels of fine particulate matter (PM2.5) in Allegheny County. 

This means the EPA determined the three-year average PM2.5 concentration was below the annual federal standard of 12.0 micrograms per cubic meter (µg/m3) based on “quality-assured, quality-controlled, and certified ambient air quality monitoring data” from 2018 to 2020.

Clean Data and Air Quality Standards

Setting aside the issue of whether the EPA’s current annual PM2.5 standard is truly protective of public health, Clean Data alone is not the final word on Allegheny County complying with that standard.

At an Oct. 12 meeting, Allegheny County Health Department (ACHD) staff laid out several issues the department still must address before EPA classifies Allegheny County as officially “attaining” the National Ambient Air Quality Standard (NAAQS) for PM2.5.

Even for regular attendees of these meetings, it was a lot to take in.

Given the complexity of the issue and the fact we get a lot of questions about how air quality standards work, we thought explaining what the meeting covered and related implications for Allegheny County “attaining” the NAAQS would be helpful. 

To start, it will be useful to understand how the EPA designated Allegheny County as a “nonattainment” area in the first place.

For air pollutants throughout the country that “may reasonably be anticipated to endanger public health or welfare,” the Clean Air Act requires the EPA to create NAAQS that, after “allowing an adequate margin of safety, are requisite to protect the public health.”

In 2012, the EPA lowered the annual PM2.5 NAAQS from 15.0 to 12.0 µg/m3. EPA stated at the time that the lower standard would “provide increased protection for children, older adults, persons with pre-existing heart and lung disease, and other at-risk populations against an array of PM2.5-related adverse health effects.”

According to the EPA, those adverse health effects may include premature mortality as well as “aggravation of respiratory and cardiovascular disease, changes in lung function, and increased respiratory symptoms.”

Having lowered the standard, the next step was for states to assess and determine what areas were not meeting the new standard. For prior NAAQS (both PM2.5 and other pollutants), the state and county have carved out specific locations (e.g., “Liberty-Clairton” or “Pittsburgh-Beaver Valley”).

In this case, Allegheny County was assessed on the whole.

In January 2015, EPA published a complete list of annual average PM2.5 levels for these areas covering the years 2011 to 2013. All locations below 12.0 µg/m3 were considered “attainment” areas and locations exceeding the NAAQS were labeled nonattainment areas. Allegheny County – at 13.4 µg/m3 – became a “nonattainment” area.

To ensure that we, as well as more than 300 million other Americans, are breathing “attainment” level air, the EPA relies on more than just the shame of the nonattainment label: The Clean Air Act demands that states with nonattainment areas create, submit for approval, and stick to what’s known as a State Implementation Plan (SIP) that will guarantee eventual compliance with the NAAQS.

Implementing a Plan for Cleaner Air

Creating a SIP is a massive undertaking that involves monitoring, modeling, and tracking emissions sources, and then creating a comprehensive plan to reduce emissions to a point that ensures ambient air quality ends up below the NAAQS.

“Think of a SIP as a federally enforceable diet. An area being labeled ‘nonattainment’ suggests it has indulged in too many poor practices for too long. To reach a healthier state of affairs, certain restrictions, reductions, and sacrifices must be made,” GASP staff attorney Ned Mulcahy explained.

And *here* is where things get complicated.

ACHD missed the deadline for submitting its SIP to the EPA. It was late, but “complete,” which is important. A “complete” SIP (i.e., it addressed all the required elements) meant ACHD would not immediately face sanctions such as reductions in federal highway funding or higher required emissions offsets for new sources (spoiler: sanctions come up again later).

Unfortunately, “complete” and “adequate” are different adjectives. As for its adequacy, EPA only “conditionally” approved ACHD’s SIP on May 14. The “conditional” part means ACHD still has work left to do.

Specifically, EPA took issue with the contingency measures in ACHD’s SIP. Such measures are back-up pollution reduction methods triggered only if the county is failing to make progress or meet milestones described in the SIP.

ACHD originally proposed using the reduction in emissions expected from the July 27, 2019, Settlement Agreement with U.S. Steel concerning emissions from its Clairton Coke Works. The EPA denied the request, responding, “[m]easures that will be implemented regardless of being triggered [by an under-performing SIP] are not considered appropriate to use as contingency measures.”

“To keep running with the diet analogy: if you aren’t hitting your goals you need to have a back-up plan that is a true change of course, not something that was going to occur anyway,” Mulcahy said.

In its May 2021 conditional SIP approval notice, EPA demanded that ACHD adopt specific contingency measures from a list specified in this letter that will provide for a reduction of up to 34 tons per year of direct PM2.5 emissions. Failure to do so by May 2022 would reintroduce the possibility of sanctions that we mentioned earlier.

Allegheny County’s Attainment Options

With all of that hanging in the balance, remember Clean Data? This is a story about Clean Data.

The timing of the Clean Data Determination meant – in essence – that before EPA could give final approval to ACHD’s “diet,” the county met its goal…sort of.

In its September 2021 Clean Data proposal, EPA said final approval of the Clean Data Determination would “suspend the requirements” that ACHD finalize its SIP measures “related to the attainment of the 2012 annual PM2.5 NAAQS.” But this came with one HUGE contingency: The suspension lasted only “so long as the area continues to meet the NAAQS, [or] until the area is redesignated to attainment.”

The problem is that falling off the wagon (so to say) – ending up with a three-year average PM2.5 level above 12.0 µg/m3 for 2019 to 2021 or 2020 to 2022 – is still possible. If that were to happen, the suspended requirements would become due, and again possibly cause EPA to impose sanctions.

By all accounts, ACHD plans to move ahead with the next step after a Clean Data Determination: formally requesting EPA redesignate Allegheny County as an attainment area. This request would include ACHD developing an approved maintenance plan, which – ironically – must include a set of “contingency” provisions.

To the best of our knowledge, ACHD also is working on the SIP contingency revisions. But with a lot of work to do and limited resources, the department could gamble on getting back into attainment (officially) or keeping Clean Data and hope any future hiccups fall under the maintenance plan.

It seems to us ACHD needs to complete the SIP ASAP. It might be work that ultimately isn’t necessary if air quality at least stays minimally compliant with the NAAQS, but we believe the best contingency plan is to remedy the contingency plan… before the next contingency plan.

Regulatory word games aside, this all suggests some level of improvement in air quality over the years, which is mildly reassuring. But are we really out of the woods? Like we said, it’s all still a bit hazy.

Editor's Note: For a deeper dive on the county’s PM2.5 “diet,” all the supporting materials for ACHD’s PM2.5 SIP are available online.

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