Why burning PFAS at the wrong temperature doesn’t destroy it — and what it actually produces instead. A technical briefing on products of incomplete combustion (PICs) and what they mean for communities near proposed PFAS thermal treatment facilities.
When a company says it will “thermally treat” PFAS-contaminated soil, the word “treat” is doing a lot of work. There is a critical difference between moving PFAS from one place to another using heat, and actually breaking the carbon-fluorine bond that makes PFAS permanent.
Thermal desorption at low temperatures (around 600°F / 315°C) drives PFAS off the contaminated soil matrix and into a vapor stream. The carbon-fluorine bond survives. The PFAS moves from the ground to the air.
Thermal destruction (mineralization) requires sustained temperatures above 1,800°F (approximately 1,000°C) in a properly designed incinerator with adequate residence time and a post-combustion chamber — and even then, the science on completeness is unresolved.
These are not the same thing. They are not even close to the same thing.
The carbon-fluorine bond is the strongest bond in organic chemistry. Nature has no mechanism to break it, and most thermal processes don’t either. At insufficient temperatures, PFAS is not destroyed — it is relocated. The soil becomes the air. The air becomes the lung.
Research has found that PFAS can begin altering from their original form at temperatures as low as 100–300°C, stripping off functional groups and creating volatile PFAS fragments that are greenhouse gases, and of which most have unknown toxicity.
At 315°C (600°F) — the temperature proposed for thermal desorption in Fort Edward — the process is not destroying PFAS. It is cooking PFAS off contaminated soil and sending it up the stack.
When PFAS thermal treatment is incomplete — which includes all thermal desorption processes and many nominally “high-temperature” incinerators — the exhaust contains a range of fluorinated products of incomplete combustion (PICs). Some are more immediately toxic than the PFAS compounds they came from.
One of the most corrosive acids known. Contact with skin causes deep tissue and bone destruction. Inhalation causes pulmonary edema and systemic fluoride poisoning. Industrial HF exposure is treated as a mass-casualty event. HF forms as a combustion byproduct whenever PFAS is heated — even in high-temperature incinerators where 82% of available fluorine has been measured coming out as HF. At 600°F, this process is uncontrolled.
Documented in laboratory PFAS combustion studies at 600°C. More acutely toxic than phosgene — the chemical weapon used in World War I. Reacts immediately with moisture in lung tissue, releasing HF and CO&sub2; internally. Colorless and nearly odorless. A 30-year-old soil processing facility with conventional air pollution controls was not designed to capture this compound.
Potent greenhouse gases with atmospheric half-lives measured in thousands of years. CF&sub4; has a global warming potential approximately 7,390 times that of CO&sub2; over 100 years. These compounds form when PFAS breaks down incompletely and carbon-fluorine fragments recombine. They are persistent in the atmosphere and contribute directly to long-term climate disruption.
Peer-reviewed research has confirmed that incomplete PFAS combustion can create PFAS compounds that did not exist in the original waste stream. CF&sub3; radicals formed after hydrogen abstraction recombine to produce larger PFAS molecules. Some of these new compounds can react in the atmosphere to form perfluorocarboxylic acids. Most have unknown toxicity. None are regulated. None are being tested for in air emissions from existing thermal treatment facilities.
The scientific literature is unambiguous: “incomplete breakdown during thermal treatment can result in reactive intermediates that can form new PFAS or other compounds of concern.”
The air pollution control systems on existing soil processing facilities — typically designed for particulate matter and conventional acid gases — have not been tested for their ability to capture PFAS emissions or PICs. This is not a disputed point. It is a documented data gap in the peer-reviewed literature.
The discussion above applies with full force to 600°F thermal desorption. But it is important to understand that even proper high-temperature incineration does not cleanly solve the PFAS problem.
At pilot-scale research combustors operating at 750–920°C, studies found “significant amounts of both polar and non-polar volatile fluorocarbon PICs” even when PFAS destruction efficiency exceeded 99.99%. High destruction efficiency does not equal zero emissions. The remaining fraction — fractions of a percent of an extremely large input mass — can still represent meaningful environmental releases.
The federal government reached the same conclusion. In 2022, Congress acted on it directly:
The 2022 NDAA imposed a federal moratorium on PFAS incineration by the Department of Defense until the DoD issues guidance implementing requirements of the Clean Air Act, including controlling hydrogen fluoride emissions.
The moratorium was triggered by a finding that “there is no proof that existing incinerators are capable of breaking down PFAS chemicals without generating additional PFAS emissions or other harmful products of incomplete combustion.”
That moratorium applied to proper high-temperature RCRA-permitted hazardous waste incinerators. Thermal desorption at 600°F is not that. The moratorium concern applies here with greater force, not less.
The question is not whether any PFAS can be destroyed thermally. Under the right conditions, it can. The question is whether this facility, at this temperature, with this air pollution control equipment, can destroy PFAS without releasing something worse. The answer is: nobody has tested it, no standard exists for it, and the regulatory framework permitting it does not require the answer before the permit is issued.
When a permit application claims that PFAS-contaminated soil will be “treated” at a thermal desorption facility, the community is being asked to accept the following:
1. PFAS that currently exists in soil will be volatilized and sent through a stack into the surrounding air — not destroyed.
2. At 600°F, some portion of that PFAS will partially break down into compounds including hydrogen fluoride and carbonyl fluoride — compounds acutely more dangerous than the original material — and these will also exit the stack.
3. Some portion will form new PFAS compounds not present in the original waste, with unknown toxicity.
4. The existing air pollution control equipment at the facility was designed for particulate matter and conventional acids — not for PFAS or its breakdown products — and has not been tested for this application.
5. No standard currently exists in the regulatory framework for what constitutes acceptable PFAS emissions from a thermal desorption stack. The permit does not require the facility to measure for PFAS or PICs in its emissions.
This is not treatment. This is relocation. Your land and your lungs are the destination.
Sign the Petition →ScienceDirect: “Review of PFAS Treatment in Combustion-Based Thermal Waste Systems” (2024) — “the possibility for PFAS or fluorinated organic byproducts to escape destruction cannot be ruled out.”
PMC / ACS ES&T Engineering: “Pilot-Scale Thermal Destruction of PFAS in Legacy AFFF” — “many PICs are greenhouse gases, most have unknown toxicity, and some can react to create new perfluorocarboxylic acids.”
PMC: “PFAS Thermal Destruction at Water Resource Recovery Facilities” — smoldering combustion at 1,000°C+ still left 18% of available fluorine unaccounted for.
Biden White House OSTP PFAS Report (2023): “incomplete breakdown during thermal treatment can result in PIDs and reactive intermediates that can form new PFAS or other compounds of concern.”
National Defense Authorization Act FY2022: Federal moratorium on DoD PFAS incineration; “no proof that existing incinerators are capable of breaking down PFAS without generating additional PFAS emissions or other harmful PICs.”
Tandfonline: “Combustion of C1 and C2 PFAS: Kinetic Modeling” — documentation of COF², CF&sub4;, C&sub2;F&sub6; and other PICs formed during PFAS thermal breakdown.