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ACHD Proposes RACT Regs to Reduce Emissions of Ozone-Forming Compounds: Here's What You Need to Know

Updated: Sep 9, 2022

The Allegheny County Health Department (ACHD) has published a proposed revision to its air quality regulations that will impose a new set of “Reasonably Available Control Technology” (RACT) requirements on major sources of oxides of nitrogen (NOx) and volatile organic compounds (VOCs) in Allegheny County.

Why? Good question: New RACT rules are required under the Clean Air Act every time the National Ambient Air Quality Standard (NAAQS) for ozone is revised. NOx and VOCs are regulated under the Clean Air Act because they contribute significantly to the formation of ground-level ozone.

Because this is the third time new RACT rules have been required, they are referred to as “RACT III.”

Most if not all major sources of air pollution in Allegheny County will be subject to the new rules. This includes:

Pittsburgh Allegheny County Thermal; Bellefield Boiler; Sunoco Pittsburgh Terminal; Brunot Island Generating Station; Imperial Landfill; Buckeye Pipeline Coraopolis Terminal; Monroeville Landfill; Kelly Run Landfill; Pittsburgh Terminals Coraopolis; Universal Stainless and Alloy; Energy Center North Shore; LHT Terminals; Springdale Energy; US Steel Clairton; US Steel Edgar Thomson; US Steel Irvin; Neville Chemical Co.; University of Pittsburgh; Liberty Polyglas Pultrusions; ATI Flat Rolled Products; and Eastman Chemicals & Resins.

Here’s how we got here: The first round of RACT determinations followed the creation of the RACT requirement by the 1990 Amendments to the Clean Air Act and were implemented in the late 1990s and early 2000s. RACT II determinations, which have only just been completed, followed the revision of the NAAQS for ozone in 2008.

That brings us to RACT III, which follows the latest revision of the ozone standard, which occurred in 2015.

We have blogged about the RACT requirement before, but to review: The RACT requirement instructs states to determine whether major sources of NOx and VOCs in areas that do not attain the NAAQS for ozone are using all “reasonably available control technology” to limit their emissions of NOx and VOCs.

These rules are important because NOx and VOCs are the two principal precursors to the formation of ground-level ozone pollution. If such sources are not implementing RACT, the states must require them to do so, even if they were properly permitted when they began operating and have continued to operate within all applicable limits.

“Although the Pittsburgh region has attained the NAAQS for ozone, all areas of Pennsylvania are deemed to be nonattainment for the purpose of implementing RACT, because the Keystone State is included in the ‘Ozone Transport Region’ established by the Clean Air Act,” GASP senior staff attorney John Baillie explained. “As a result, all major sources of NOx and VOCs in Pennsylvania will be required to comply with RACT III emission limits.”

ACHD proposes to implement RACT III by including the Pennsylvania Department of Environmental Protection’s (DEP) RACT III regulations fully by reference into Allegheny County’s Air Pollution Control regulations.

“Accordingly, RACT III will generally be implemented by imposing new emission limits for NOx and/or VOCs called ‘presumptive limits’ on certain categories of sources by regulation,” Baillie said. “A source may petition to opt out of such regulatory limits, but the reviewing agency would still have to determine RACT for the source on a case-by-case basis.”

A case-by-case RACT determination for a facility generally requires the facility to identify all “technically feasible” controls for its NOx or VOC emissions, and then determine whether such controls are “reasonably available” using a cost-benefit analysis that looks specifically at the cost per ton of NOx or VOC emissions that each control would remove.

For RACT III, it is believed that sources in Pennsylvania that opt out of presumptive RACT III limits will be required to implement NOx-limiting controls with a cost-effectiveness of $7,500/ton, and VOC-limiting controls with a cost-effectiveness of $12,000/ton.

The presumptive limits in the RACT III regulations will cover several categories of sources that were not covered by RACT II’s presumptive limits, including certain (with “certain” meaning “depending on their capacities or ratings”):

  • natural gas compression and transmission facilities

  • rich burn stationary internal combustion engines

  • solid fuel (but not coal) combustion units

  • certain direct-fired heaters, furnaces, ovens, glass melting furnaces, and lime kilns.

It should be noted that for the remaining coal-fired electric generating units in Pennsylvania, RACT III limits will be determined on a case-by-case basis.

RACT III will also lower some of RACT II’s presumptive limits, including those for: certain combustion turbines, certain lean burn stationary internal combustion engines, and Portland cement kilns.

DEP estimates that implementing RACT III could reduce NOx emissions on a state-wide basis by as many as 9,000 tons per year and yield a corresponding state-wide health benefit valued at between $337 and $732 million.

ACHD’s proposed RACT III regulations are available by a link on ACHD’s website.

As mentioned above, the proposed RACT III regulations will impose new limits on rates of emissions from certain source categories and are thus technical in nature, but ACHD is accepting comments on them through Aug. 18 by email at

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