PFAS-based Aqueous Film-Forming Foam

Aqueous film-forming foam, or AFFF, is a chemical foam that fire departments and other organizations worldwide use to fight fires involving flammable liquids. AFFF contains per- and polyfluoroalkyl substances, or PFAS, as such chemicals serve as the backbone structure of the foam. PFAS pose health risks, mainly because they can accumulate in the body over time and can cause numerous health issues, such as hormonal dysfunctions. In the 1960s, the United States Naval Research Laboratory, in collaboration with a private chemical company, developed AFFF to enhance capabilities to fight fires involving jet fuel aboard naval ships. The effectiveness of the foam is mainly due to the structure of PFAS, which allows AFFF to spread quickly over burning fuel, suppressing vapors and cutting off the oxygen necessary for the fire. Since its development in the 1960s, many versions of AFFF have been marketed for firefighting purposes. Despite its effectiveness in suppressing flammable-liquid fires, AFFF poses risks for many groups, including firefighters, pregnant women, and their fetuses.

1. How Does AFFF Extinguish Fire?
2. Historical Background
3. Current Products and Policies
4. Consequences of the Invention of AFFF
5. Conclusion

How Does AFFF Extinguish Fire?

Aqueous film-forming foam is a specialized firefighting foam designed to extinguish flammable-liquid fires by creating a film of water that prevents fuel vapors from escaping and blocks oxygen from reaching the fire. AFFF contains PFAS, which are chemicals that lower the surface tension of water, allowing the foam to spread quickly over the fuel surface and forming a barrier that prevents fuel vapors from escaping and cuts off the fire’s oxygen supply. By smothering the flames and cooling the fuel, AFFF suppresses the fire and reduces the risk of re-ignition. All such features make AFFF effective in fire scenarios involving oil spills and jet fuels. However, after the foam serves its purpose, firefighters can’t control how the AFFF and the chemicals in it are disposed of, despite their dangers, or prevent its dispersal into the environment.

Historical Background

Aleksandr Loran invented the first AFFF. A high school teacher in Baku, the Russian Empire, the Republic of Azerbaijan as of 1991, Loran lived between 1849 and 1911 and studied chemical engineering in Paris. In 1902, he created the first form of foam as a liquid solution that would float over the flaming oils, consuming the oxygen needed by the fire for combustion and extinguishing it. Following Loran’s initial work, chemist Joseph Simons introduced the scientific community to the means of producing PFAS in the 1940s. The chemicals are responsible for the firefighting properties of AFFF. The PFAS allows the foam to control water and oils, including gasoline, creating a barrier between firefighters and the fire and preventing the inhalation of fuel vapors.

In the mid-1960s, the US Navy collaborated with the company 3M in St. Paul, Minnesota, specializing in the innovation and sale of industrial and consumer products, on producing a new solution capable of extinguishing fuel-based fires aboard their aircraft carriers. In the 1970s, the US Department of Defense started using AFFF in all military installations, and by the beginning of the 1980s more than ninety civil airports stocked the foam. In 1993, Pyrocool Technologies, from Monroe, Virginia, created a type of fire-extinguishing foam, called Pyrocool FEF, with a reduced environmental footprint as compared to AFFF, designed for wildfires and fires that involve combustible metals, like magnesium and potassium. At the time of development, the researchers behind Pyrocool FEF described the new fire-extinguishing foam performing similarly to AFFF for fighting fires involving hydrocarbon-based fuels, while releasing a minimum of PFAS into the environment.

Current Products and Policies

PFAS-based foams have been part of the typical toolkit for firefighters in many countries since the 1990s, establishing the foams as an effective means for suppressing fuel-based fires at airports, military bases, and industrial settings. When needed, firefighters mix the foam concentrate with water from the fire truck’s reserves or the city water supply, with common dilutions being 1 percent, 3 percent, and 6 percent, and adapting fire trucks to carry AFFF reservoirs is possible. AFFF initially produced for the US Navy contained PFAS compounds such as perfluorooctane sulfonate, or PFOS, that the company 3M determined most effective against fuel-based fires, even though the company also knew at that time that PFOS was not biodegradable and, by the late 1970s, that the compound was toxic.

On 29 June 1998, the US Environmental Protection Agency recognized Pyrocool Technologies, Inc. with the Green Chemistry Challenge Small Business Award for developing Pyrocool FEF. At the time of the prize, researchers described Pyrocool FEF as an improvement over AFFF used by the Navy, with a significant reduction of PFAS exposure, as firefighters can mix the product with water at a 0.4 percent concentration, while still effectively fighting fires that involve hydrocarbon-based fuels and polar solvents.

In the first decade of the 2000s, the EPA began the 2010/2015 PFOA Stewardship Program, and manufacturers of traditional AFFF such as 3M started a phase out of those chemicals and to create PFOS-free foams. The voluntary program had the goals of achieving a 95 percent reduction of PFOA emissions and product-content levels by 2010 and a total elimination by 2015. The National Defense Authorization Act for Fiscal Year 2020 further required the US Department of Defense to discontinue the use of AFFF with PFAS at their military installations starting 1 October 2024, though with the possibility of extensions until 2026 and excluding military ships.

The newer firefighting foams perform with a reduced chemical footprint on the environment with government agencies such as the Alaska Department of Environmental Conservation claiming that the replacement of PFOS with shorter-chain molecules causes newer foams to be less toxic. In 2002, the company BIOEX based in Sainte-Consorce, France, tested the first fluorine-free foam, ECOPOL. BIOEX marketed the foam as having capabilities similar to traditional AFFF while being partially biodegradable due to the absence of fluorine, which, according to the researchers who developed BIOEX, is one of the reasons PFAS last so long in the body and the environment.

Moreover, AFFF is not as effective as newer inventions are in extinguishing fires occurring in some technologies, such as lithium-ion batteries, because of the foam’s base. Recent research demonstrates that while dry chemical and Class-D powder extinguishers can temporarily suppress lithium-ion battery fires, they frequently fail to prevent reignition, and aqueous agents, such as water mist, prove more effective at both extinguishing the fire and preventing its return, due to superior cooling effects. Although dry chemicals may still pose challenges in terms of environmental control and composition, the research highlights the limitations of traditional agents for these advanced battery technologies.

Consequences of the Invention of AFFF

Though the scientific and firefighting community initially embraced AFFF for its effectiveness in controlling large and hazardous fires, research in the following decades revealing the harmful effects of PFAS resulted in many newer versions of firefighting foam with the common goal of achieving comparable effects while reducing PFAS content. Governments internationally are banning the use of PFAS-based AFFF. In 2010, the European Union banned production of firefighting foam with PFOS under Commission Regulation (EU) No. 756/2010 and Commission Regulation (EU) No. 757/2010. In June 2013, the government of Canada also banned its production, supply, and use, with some military exemptions. Despite those policies, there are challenges with fully eliminating PFAS-based AFFF, including compatibility issues with newer foams regarding their inability to withstand certain temperatures or to be mixed with water in advance of use, significant costs in transitioning away from AFFF, and firefighters requiring different training in the use of the replacement foams.

Furthermore, a summary of research from a 2020 article in the Journal of Water Process Engineering highlights the dangers of prolonged PFAS exposure, linking them to negative maternal health outcomes such as reduced fertility and increased risk of adverse birth outcomes like low birth weight, neuropsychological disorders, and dysfunction in motor skills. In 2024, an article in the journal Current Environmental Health Reports analyzed how the PFAS in AFFF deposit in the placenta, where they can disrupt mechanisms that are responsible for fetal and maternal health, as well as the body’s immune system.

Conclusion

PFAS-based AFFF opened many opportunities in firefighting because of its ability to suppress dangerous fuel-based fires efficiently. Many firefighting institutions still use PFAS-based foams as of 2024 due to several difficulties replacing them. But after decades of research raising concerns about the content of PFAS in AFFF, innovations have pushed the development of fire-extinguishing foam toward what are thought to be safer and more sustainable alternatives, like ECOPOL. Furthermore, government agencies internationally have issued guidelines and passed legislation to address the risks of PFAS in AFFF.

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