Regulatory Alert: D.C. Circuit Affirms EPA’s Rule Designating PFOA and PFOS as CERCLA Hazardous Substances

August 18, 2026

Today, the U.S. Court of Appeals for the D.C. Circuit issued a unanimous decision affirming a Biden-era rule from the U.S. Environmental Protection Agency (EPA) that designated two PFAS chemicals, PFOA and PFOS, as “hazardous substances” under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), known as the Superfund law. The rule and designation, which went into effect in July 2024, provided the EPA with the authority to respond to releases of PFOA or PFOS in the environment and to address hazards caused by historical releases of these chemicals through cleanups of the contaminants.

Soon after being issued, the Chamber of Commerce, along with other organizations (referred to as the “petitioners”), legally challenged and sought to overturn the EPA’s rule, raising similar arguments that AAAE submitted in 2022 in response to the agency’s proposed rule. One of the primary arguments was that the EPA did not properly consider the cost impacts of the hazardous substance designation. In September 2025, the Trump administration announced that the EPA would defend the rule in the ongoing litigation. The administration’s support for the rule, along with the decision issued today, affirms that it will remain in effect indefinitely absent congressional action or the case being heard by the U.S. Supreme Court.

In terms of impacts for airports, the EPA continues to maintain the “PFAS Enforcement Discretion and Settlement Policy Under CERCLA,” which was issued along with the rule in 2024. The policy provides that the EPA will not pursue PFAS response actions or cost recovery from some entities, including publicly owned airports, because they were innocent users of these chemicals. While EPA’s policy provides some level of protection, airport sponsors may still be subject to private party actions. As a result, AAAE has continued, and will continue, to advocate for Congress to provide airports with CERCLA liability protection based on the longstanding FAA mandate for airport operators to use AFFF.

Background on CERCLA. Under CERCLA, EPA has the authority to respond directly to releases, or threatened releases, of any “hazardous substances” that may endanger public health and/or the environment. The statute gives EPA the authority to conduct or order two types of responses: short-term “removal” actions when there is a release or threatened release and long-term “remedial” actions to permanently and significantly reduce risks associated with releases of the substance. Most importantly, CERCLA imposes retroactive, joint and several, and strict liability on parties that are responsible, in whole or in part, for the release of any hazardous substance.

EPA’s PFOA/PFOS CERCLA Rule. In 2022, the EPA released a proposed rule that would designate PFOA and PFOS as CERCLA hazardous substances. This was the first time that EPA exercised its authority to designate any substances as hazardous under the statute. The agency based the proposed designation on the potential human health and environmental hazards associated with exposure to the chemicals. In our response, AAAE argued that such a designation would be a draconian measure that unfairly punishes airports for procuring and using AFFF in accordance with an FAA mandate and ignores the cost-related impacts. We also urged the EPA to provide airports with protection from CERCLA liability.

In 2024, the EPA released a final rule with the hazardous substance designation for PFOA and PFOS. The agency emphasized that that it gave “serious consideration” to concerns over the possibility of some entities being exposed to liability even though they did not manufacture or generate PFOA or PFOS-containing materials. These considerations led to the issuance of the “enforcement discretion and settlement policy.” Under the policy, EPA stated its intent to not pursue enforcement against certain entities where equitable factors do not support seeking response actions or costs under CERCLA. Publicly owned airports and local fire departments are included in the list of these entities.

Legal Challenge to EPA’s Rule. In 2024, the Chamber of Commerce petitioned the D.C. Circuit Court of Appeals to overturn the EPA’s rule on the grounds that the agency (a) misapplied its authority under the Superfund law in designating PFOA and PFOS as hazardous substances and (b) prepared its cost-benefit analysis (BCA) improperly and without adequate notice. In today’s decision, the court rejected both arguments, finding that the EPA “adequately considered and reasonably explained” its decision to issue the rule; the EPA’s BCA was not prepared in an arbitrary or capricious manner; and other protections exist to ensure benefits and costs are considered before any responsible party faces CERCLA liability.