Understanding AFFF and Its Critical Role in Firefighting
Aqueous Film Forming Foam (AFFF) is a fire suppressant that has been widely used since the 1960s for fighting flammable liquid fires. Made up of fluorosurfactants and other chemicals mixed with water, AFFF works by coating the surface of burning hydrocarbon fuels to prevent reignition.
AFFF is highly effective at extinguishing fires involving fuels like gasoline, oil, and jet fuel. Its fluidity and rapid extinguishment ability make it the go-to suppressant used by military, commercial airports, oil facilities, and fire departments. It has saved countless lives and property over the past 60 years.
When sprayed onto a burning fuel, AFFF produces a aqueous film that spreads across the surface. This film serves several firefighting purposes:
- It separates the fuel from oxygen and prevents off-gassing of flammable vapors.
- It cools the fuel surface and any metal surfaces beneath it.
- The aqueous film provides superior heat absorption compared to plain water.
- It adheres extremely well to vertical and inverted surfaces where flammable liquids may spread.
These properties have made AFFF indispensable for fighting liquid fuel fires that plain water cannot extinguish effectively.
The Composition of AFFF: What Makes It Effective?
The effectiveness of AFFF comes from its specialized formulation that produces an aqueous film capable of suppressing fires even at low concentrate volumes between 0.5-6%.
AFFF contains four main components:
Fluorosurfactants – Synthetic fluorinated compounds that reduce surface tension of the foam solution and facilitate aqueous film formation. Historically based on toxic PFOS or PFOA but modern AFFF uses shorter-chain fluorosurfactants.
Hydrocarbon surfactants – Help the foam solution spread across hydrocarbon-based fuel surfaces.
Solvents – Increase the foam stability and help it adhere to fuels. Common solvents include glycols and alcohols.
Other additives – Small percentages of corrosion inhibitors, foam stabilizers, and freeze/flow additives are included in the mixture.
The fluorosurfactants are vital since they enable the formation of an aqueous film that can quickly spread, seal fuel surfaces, and prevent reignition. However, they have also been linked to negative health and environmental impacts.
Historical Development and Use of AFFF
1952 – AFFF was invented by the US Naval Research Laboratory as a fire suppressant superior to protein-based foams used at the time.
1960s – Refinements lead to the adoption of AFFF by military branches. Use expands to commercial airports and the oil/gas industry.
1970s-1980s – AFFF formulations utilize PFOS and PFOA as key ingredients. Large stockpiles created by military around the world.
1990s-2000s – After health concerns over PFOA/PFOS emerge, manufacturers reformulate AFFF using shorter chain fluorosurfactants or telomers. Legacy PFOS foams still used from existing stockpiles as they cannot be easily replaced.
Today – Global AFFF market size is over $650 million. Over 5 million gallons of PFOS-based AFFF remain stockpiled for emergency use in the US. Disposal has been highly difficult and existing contamination is still being dealt with.
AFFF’s Environmental Impact: The PFAS Connection
AFFF has contaminated soil and groundwater at many military sites, airports, refineries, and fire departments globally. PFAS chemicals from AFFF do not easily break down and persist for years. Exposure pathways include:
Direct Runoff – AFFF sprayed during firefighting drills or emergency responses flows into soils, storm drains, streams/lakes leading to extensive groundwater contamination plumes.
Infiltration – Over time, PFAS from stored AFFF containers or fire suppression systems leaches through soils to groundwater. At some sites, aquifers have become heavily contaminated.
Landfill Leaching – Attempts to dispose of unused foam by landfilling has resulted in PFAS leaching from landfills.
Several sites around the world have faced drinking water well closures, health advisories, fishery/livestock impacts, and massive environmental cleanup efforts due to PFAS contamination traced back to AFFF usage.
Health Concerns Linked to AFFF Exposure
The bioaccumulative and persistent nature of certain PFAS compounds makes them hazardous to human health. Firefighters face elevated exposure risks from direct contact with AFFF spray. Associated health impacts include:
- Increased cholesterol levels
- Changes in liver enzymes
- Decreased vaccine response in children
- Increased risk of high blood pressure in pregnant women
- Potential increased cancer risk
Drinking water contamination caused by AFFF entering water supplies poses severe health threats to communities near sites where it has been used. Sensitive groups like children and pregnant women are especially vulnerable.
While toxicity studies on newer short-chain PFAS replacements for PFOA/PFOS are still limited, precautions should be taken to avoid exposure from any AFFF foam usage.
Regulatory Framework Governing AFFF
Growing awareness of potential harms has led to a constantly evolving legal landscape around restricting PFAS and regulating AFFF usage:
Production Phase-Outs – Manufacture of PFOA, PFOS, and related chemicals has been mostly phased out in the US, Canada, EU due to persistence and toxicity concerns. Telomer-based short-chain fluorosurfactants largely replaced them.
Use & Discharge Restrictions – Many states have implemented storage and usage restrictions on AFFF foams containing PFAS for testing/training. Additionally, federal aviation and military specifications prohibit AFFF discharge other than emergency responses.
Stockpile Management – The US military has guidelines stipulating that only PFOS-based AFFF foams can be used for liquid fuel fires. While use in regular testing is restricted, legacy AFFF cannot yet be fully replaced which has led to continued potential for release into the environment. Similar stockpiles likely exist internationally.
Cleanup & Disposal Regulations – Sites contaminated by AFFF releases have faced regulatory pressure and lawsuits to clean up soil/groundwater contamination and provide drinking water treatment to impacted communities. However, disposal options remain extremely limited.
Challenges in AFFF Cleanup and Remediation
Extensive PFAS contamination from AFFF poses unique challenges for site remediation:
- PFAS chemicals resist standard environmental breakdown and treatment methods.
- Contaminant plumes often spread large distances requiring extensive pump-and-treatment efforts.
- Cleanups are resource-intensive and communities impacted by loss of drinking water face long waits. Costs can exceed hundreds of millions at single sites.
- Incineration remains the only proven dispose method but capacity is severely limited; landfilling and underground injection have faced regulatory blocks.
Despite widespread phaseouts of PFOA/PFOS manufacturing, their extreme persistence means contamination will continue to pose risks for years until new remediation techniques or cheaper destruction options are developed.
Emerging Alternatives to AFFF
The search for effective substitutes without the drawbacks of PFAS has led to growing interest in fluorine-free foams (F3) that use hydrocarbon or silicone surfactant formulations. However, meeting effectiveness benchmarks and getting approval has been challenging.
Adoption of alternatives faces considerable obstacles:
- Performance Concerns – Mission-critical military and aviation applications require proven fire extinguishment capability that F3 foams have struggled with during testing.
- Retrofitting Infrastructure – Billions have been invested over the past 40 years in AFFF distribution networks and fire suppression infrastructure which complicates transitions.
- Cost – Synthetic fluorine-free foams currently average 2-10x the price of AFFF counterparts.
- Toxicity Unknowns – Health/environment data on new formulations remains limited. Siloxane F3 foams have faced concerns over breakdown byproducts.
Despite these constraints, major innovation funding has sparked optimism that F3 foams can capture 20-40% of the market within the next decade.
The Future of Firefighting Foams: Beyond AFFF
While further AFFF contamination can be prevented by regulatory restrictions and best practice reforms, existing environmental and health impacts will endure without technological advances. Some promising directions that may expand remediation options include:
Bioremediation Methods – Enzyme/microbe-based bioremediation has shown promising PFAS treatment potential in lab trials and may offer a cost-effective option for extremely dilute contaminated groundwater plumes.
Plasma Technology – High temperature plasma reactors have demonstrated capability to break carbon-fluorine bonds in PFAS compounds during initial testing. If efficiency and costs improve, this could hugely expand disposal options.
Nanomaterials – Researchers are actively developing new sorbent materials using nanotechnology that can selectively capture PFAS compounds in drinking water systems and potentially in contaminated groundwater or soil too.
Advanced Oxidation – Strong research interest in using hydroxyl radicals and other oxidants that react with PFAS could improve treatment options for contaminated water.
While AFFF possesses unmatched firefighting capability, its PFAS risks call for careful handling and disposal. Stewarding innovation in fluorine-free alternatives and breakthroughs in detection/treatment methods will ideally allow society to meet public safety needs while protecting environmental and human health.
