For two decades, the federal government has classified the heated chambers used to break down plastic waste as incinerators, subjecting them to some of the strictest air-pollution controls on the books. Now the Environmental Protection Agency wants to change that, and the proposal is buried inside a rule about wildfire cleanup.
In a Federal Register notice published March 20, 2026, the EPA asked the public whether it should revise the definition of “municipal waste combustion unit” under the Other Solid Waste Incineration (OSWI) standards to exclude pyrolysis units, the core technology behind what the plastics industry calls “chemical recycling” or “advanced recycling.” If the agency finalizes that single definitional change, these facilities would no longer need to meet the emission limits Congress required for solid waste incinerators under Clean Air Act section 129.
What pyrolysis actually does
Pyrolysis heats plastic waste in a low-oxygen environment to break polymer chains into smaller molecules. The outputs vary by temperature and feedstock but typically include a synthetic oil that can be refined into fuel or chemical feedstocks, combustible gas, and a solid residue called char. Proponents say the process can divert hard-to-recycle plastics from landfills and feed them back into manufacturing. Critics counter that the process still burns fossil-fuel-derived material, releases hazardous air pollutants such as volatile organic compounds, dioxins, and furans, and produces yields too low to justify the pollution risk.
The distinction matters because Clean Air Act section 129 imposes maximum achievable control technology (MACT) requirements on solid waste incinerators, including continuous emissions monitoring and strict limits on particulate matter, acid gases, and heavy metals. Removing pyrolysis units from that framework would shift oversight to less demanding provisions, or potentially to state-level permits that vary widely in stringency.
A regulatory tug-of-war spanning three administrations
The fight over how to classify pyrolysis is not new. In 2005, the EPA finalized OSWI standards (70 FR 74870) and stated in the preamble that pyrolysis/combustion units, described as two-chamber incinerators, qualified as OSWI units. That classification stood as the regulatory baseline for 15 years.
On August 31, 2020, the Trump administration proposed stripping pyrolysis/combustion units from the OSWI definition (85 FR 53516). The Biden EPA withdrew that provision on June 5, 2023 (88 FR 36499), concluding the reclassification was premature and that the agency lacked sufficient data on how these units operate and what they emit. The current proposal from EPA Administrator Lee Zeldin effectively revives the same change that was pulled three years ago.
Zeldin framed the March 2026 rule around wildfire prevention and disaster recovery, announcing streamlined permitting for air curtain incinerators used after natural disasters. But the agency’s own news release acknowledged a second purpose: clarifying that the OSWI rule does not regulate pyrolysis units used in advanced recycling. The EPA also said public comments received through this process will inform a separate proposed rule on advanced recycling, signaling that the March action is a gateway to broader deregulation rather than a standalone technical fix.
Congress is working a parallel track
On Capitol Hill, the Recycling Technology Innovation Act (H.R. 6566), introduced in the 119th Congress, would amend the Clean Air Act to exclude certain plastic conversion units from the definition of “solid waste incineration unit.” The bill also creates a petition pathway allowing operators to ask the EPA to grant additional exclusions for new technologies. No committee hearing or vote has been scheduled as of May 2026.
If both the rulemaking and the legislation advance, the plastics industry would gain two parallel routes to lighter regulation: one through administrative reinterpretation and one through statute. That dual path would also make it harder for a future administration to reverse course, since undoing a law requires Congress while undoing a rule requires only another rulemaking cycle.
The data gap at the center of the debate
What is conspicuously absent from the March 2026 proposal is emissions data. The EPA has not published projected air-quality impacts from reclassifying pyrolysis units. In September 2021, the agency issued an advance notice of proposed rulemaking to gather information on pyrolysis and gasification units, including process descriptions and potential feedstocks. That data-collection effort was supposed to help the agency evaluate how best to regulate these facilities, but no updated findings appear in the docket for the current proposal.
Environmental groups have warned that loosening oversight could increase toxic emissions in communities already overburdened by industrial pollution. But without facility-level modeling, stack-test results, or cumulative impact assessments in the federal record, neither supporters nor opponents can point to a comprehensive government analysis of what reclassification would mean for air quality. The public comment period is proceeding against a thin evidentiary record.
What the reclassification would actually change
Two questions will determine the practical impact. First, will the EPA finalize a definition that exempts pyrolysis units from OSWI standards before it completes a separate rulemaking on advanced recycling? Doing so would decide the classification question ahead of a broader policy debate, locking in a lighter regulatory category before the agency has published the emissions analysis it said it needed.
Second, will Congress act on H.R. 6566 in a way that codifies a narrower definition of solid waste incineration, or will the bill stall and leave the issue to swing with each administration? The interplay between the legislative and administrative tracks will shape whether communities near proposed facilities can rely on federal emission standards or must depend on a patchwork of state permits.
The public comment window on the March 2026 proposal remains the most immediate point of leverage. For residents, local officials, and advocacy organizations on both sides, the dense Federal Register language about “municipal waste combustion units” carries consequences that extend well beyond terminology. How the EPA draws the line between recycling and incineration will determine what gets monitored, what gets controlled, and what gets released into the air.
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*This article was researched with the help of AI, with human editors creating the final content.
