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Removing PFAS — Trading Forever Chemicals for a Safer Firefighting Foam

January 13, 2025

Each day Port of Seattle firefighters work to keep people and property safe. Because the Port of Seattle Fire Department (POSFD) is located at Seattle-Tacoma International Airport (SEA), they protect aircraft, travelers, staff, and airport facilities. Now, in the midst of regular firefighting activities, POSFD is taking the lead on another urgent operation to increase safety for people and the planet — removing firefighting foam from the firetrucks, which contain forever chemicals, known as PFAS, that pose a threat to human health and our environment. The foam will be replaced with a new fluorine-free foam.

Since 2018, POSFD has helped lead the national transition away from PFAS foam. And today SEA Airport is the first airport operation in the U.S. to use a cleaning technology to remove PFAS chemicals from its trucks. The department cleaned each of its five trucks and three of King County’s trucks, with each taking about a week to clean. The Port of Seattle fire truck cleaning was completed at the end of July. With this initial transition work complete, the Port will now address the foam system in SEA’s Rental Car Facility fueling areas and support the transition from PFAS in tenant spaces like the airport fuel terminal and hangars with foam systems.

Per- and polyfluoroalkyl chemicals, or PFAS, have been used since the 1960s in foams to extinguish high-hazard petroleum-fueled fires — critical in saving lives and preventing catastrophe at airports, military bases, and fossil fuel refineries. Before 2023, U.S. airports were required by the Federal Aviation Administration (FAA) to use PFAS foams for aircraft firefighting. In recent years, studies pointed to PFAS’ harm to people and the environment. In September 2023, the FAA approved the first non-PFAS firefighting foam for use at commercial airports, making it possible for the transition to PFAS- free products at Washington state’s 11 airports. In addition, in 2018, the state of Washington passed legislation that bans the use of PFAS-containing products for training purposes, and restricts the purchase of additional PFAS-containing foams. SEA Airport has begun the transition to a PFAS-free foam ahead of the fall 2025 deadline restricting the purchase of new foam by federally-certified airports.

Learn more about PFAS, their role in firefighting foams, the removal process, and the Port’s work to create a safer place for humans and the environment.

How is fighting a fire different at an airport?

Airport firefighters work around aircraft that contain a lot of aviation fuel. Water alone will not suppress petroleum-fueled fires, so airport fire departments carry large amounts of foam in fire trucks.  POSFD’s fire trucks each hold 3,000 gallons of water and 400 gallons of foam which mix to extinguish a petroleum-based fire.

When firefighters apply foam to a fire with fuel vapor (gas that forms on top of the liquid layer and is highly flammable), like a fire on an aircraft, it helps suppress the fire and allows people to evacuate. The foam forms a thick, stable blanket that can cover the burning material.

Here’s how it works to suppress the fire:

  • Separation: The foam blanket isolates the fuel surface from oxygen, which is necessary for combustion
  • Cooling: The water content in the foam helps cool the fuel and surrounding surfaces, lowering the temperature below the ignition point
  • Suppression: The foam blanket suppresses the release of flammable vapors from the fuel, preventing re-ignition

A structural fire can typically be put out using water alone, but any fire that contains fuel, needs foam to help extinguish the fire.  

Aqueous-film-forming foam (AFFF) was developed in the 1960s when the U.S. Navy began working with 3M to create more effective firefighting products. In 1966, the Navy patented a fire-suppressing foam that contained PFAS (per- and polyfluoroalkyl substances), a family of human-made chemicals that have been used in industry and consumer products since the 1950s.

When AFFF is placed on a flammable liquid fire, it creates an adhesive layer over the fuel and suppresses the vapor keeping it from burning.  However, because of dangers to human health and the environment, POSFD is currently removing this foam from trucks before a new fluorine-free version is added.  


How is fluorine-free foam different from AFFF?

The fluorine-free foam that will replace AFFF is PFAS-free, making it a more environmentally and people-friendly option. It works by creating a physical barrier between the fuel and oxygen by using bubbles to prevent the fire from spreading, and to cool it down. It needs to be managed more aggressively than AFFF, but it still extinguishes the fire effectively and quickly.

How can PFAS impact public health?

According to the Washington State Department of Health, PFAS are a public health concern because they:

  •  Build up in animals, fish, birds, plants, and people and impact their overall health
  • Don’t break down quickly or easily in water, soil, or air
  • Travel large distances in water or air

PFAS can be found in products like food packaging, outdoor clothing, and non-stick pans. Most people living in the United States have some amount of these chemicals in their blood.  People in communities with local PFAS contamination in their drinking water or food or who work closely with PFAS often have higher exposure and may be more likely to have negative health impacts. The Washington State Department of Health now requires drinking water systems to test their water supplies for PFAS. Find information about PFAS in drinking water→

Learn more about PFAS and their impacts→ 

Why is it so challenging to remove PFAS from the environment?

PFAS are both attracted to and repelled from water and oil, which creates the nonstick property it is known for. These chemicals can move freely and attach easily to most things.  As a result, removing PFAS from the inside of fire trucks and hoses is challenging. The majority of technologies historically used for environmental cleanup are not as effective for PFAS, because they don’t behave like other chemicals.  

When fluorine and carbon are bonded together it creates one of the strongest natural bonds that exists. Scientists are working to develop new techniques to effectively deconstruct PFAS. Some of the technologies in development use high pressure and/or high temperatures to break apart the strong carbon-fluorine bond. The biggest challenge of addressing PFAS in the environment is how to expose soil and groundwater where PFAS is found to the processes that are able to destroy the molecule.


How does the PFAS cleaning process work on trucks and why is it effective?

The effectiveness of available options to remove PFAS from firefighting truck tanks and hoses can be compared to washing dishes in a dishwasher. If you put dishes in the dishwasher and use cold water, they don’t come out clean. If you add warm water, they may get a little bit cleaner. But when you add a little soap, that’s when the dishes really get clean. That’s the equivalent of the cleaning process POSFD is using on its trucks.

The Port is contracting with TRS Group, Inc. for the safe and effective removal of the foam from trucks. Using TRS Group’s patented technology, concentrations of PFAS are expected to be reduced by more than 99% and generate little waste. Seven commercial international airports in the U.S. have phased out their PFAS foams using water alone. But SEA Airport is the first to use a cleaning technology.

TRS uses a solution-based additive called PerfluorAd, which can be compared to an organic dishwashing soap, that pulls off PFAS that attaches to the nooks and crannies of the truck, like a dishwater in a warm, sudsy environment.

Here’s how the process works:

  1. The solution is mixed with water and is heated before being circulated into the pipes and tank on the truck
     
  2. The solution binds with the PFAS to pull it from the tank and pipes through a process called flocculation, creating a jellylike substance that floats in the water, that is then removed through filters which capture the jellylike PFAS sludge
     
  3. Next the water is filtered through liquid granular activated carbon to remove the remaining PFAS from the water stream
     
  4. Cleaned water is reused, and eventually discharged into the sewer (approved by the King County Wastewater Division)

Flowchart graphic showing the PFAS removal process.

How is the Port leading the way in PFAS removal?

In 2018, ahead of regulation, Port staff began assessing the use of the firefighting foam which included gathering historical records, newspaper articles, information on fires and responses, and interviewing firefighters. Since then, the Port has worked diligently with local, state, and national partners to bring attention to the need for foam replacement, and they have continued to lead the way in finding and implementing the most effective form of removal and replacement of PFAS from the firetrucks ahead of schedule.

There is currently no guidance on how to remove PFAS from trucks and no requirement to do so. As the first fire department in the U.S. to use the cleaning technology at scale, SEA Airport is sharing data and learnings from the experience with other airports across the nation. Port staff is tracking and documenting lessons learned and experiences from the process to educate themselves and the industry on best practices moving forward.

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