Aqueous film-forming foam (AFFF)

fire extinguisher
Aqueous film-forming foam (AFFF) is a type of foam used to fight liquid-fueled fires. Fire departments use AFFF to fight liquid-based fires (i.e., those started by oil, gasoline, or other flammable liquids).

AFFF is highly concerning because it contains PFAS (per- and polyfluoroalkyl substances). PFAS are toxic chemicals known to negatively impact human health and do not easily break down in the environment, waterways, wildlife, or human bodies.

  • PFAS are linked to negative health impacts in humans, including cancer.
  • AFFF is the leading cause of PFAS contamination in drinking water.

As of 2018, Washington passed a law that restricts AFFF because of the dangers of PFAS.

Learn how PFAS gets into the environment

What are the dangers of AFFF?

​AFFF is a key suspected source of PFAS-contamination in Washington drinking water.

PFAS pose risks to humans and wildlife, such as:

  • Reproductive impairment.
  • Increased cancer risk.
  • Reduced immune system response.

It is estimated that nearly all Americans have some amount of PFAS in their blood.

How does AFFF contaminate drinking water with PFAS?

The most common ways that PFAS have contaminated drinking water is by way of using AFFF for fire suppression activities, such as:

  • Putting fires out.
  • System testing (e.g., required testing at airports).
  • Fire training (Note: AFFF is banned for fire training as of 2018).
  • Spills or accidental release.

Once PFAS are released into the environment, they are difficult to clean up because they:

  • Easily dissolve in water.
    PFAS are highly mobile and can quickly contaminate groundwater, drinking water, and other natural areas.
  • Do not break down naturally.
    PFAS build up in the environment over time with no natural way to be removed, which may increase our risk of exposure to PFAS for hundreds or thousands of years.

Why does AFFF contain PFAS?

PFAS are the chemicals that create the “film” in aqueous film-forming foam. They put fires out by cutting off the oxygen between the flammable liquid and air, which is what keeps fires burning once ignited.

PFAS are used because of their ability to:

  • Resist heat.
  • Easily dissolve in water.
  • Spread quickly so they put out fires faster.

What are we doing about AFFF?

In 2018, the Washington State Legislature passed a law that restricts AFFF. In Washington, AFFF is now banned for most purposes. It can no longer be:

  • Manufactured.
  • Sold.
  • Used for fire training.

AFFF is still allowed for emergencies and actual fire situations that require it, until an alternative is found.

Fire department icon
AFFF collection and disposal program

To help fire departments safely dispose of their AFFF, we are developing a program to collect and dispose of AFFF.

This program will launch after we publish a draft Environmental Impact Statement (EIS) and conduct a public comment period.

Timeline of past and future activities

Reducing AFFF at airports

Under federal law, commercial airports in Washington must test their ability to dispense AFFF (which contains PFAS) each year. These tests:

  • Can disburse thousands of gallons of PFAS on the ground.
  • If not carefully collected, the PFAS from AFFF can contaminate groundwater and drinking water.

In 2021, our input-based test box program at airports started. It provides airports with funds to purchase equipment that allows them to test their firefighting capabilities without the need to put AFFF on the ground.

Watch our video about input-based test boxes to learn more.