Above the Clouds, Below the Standards: PFAS in Commercial Aviation
Commercial aviation operates under exacting safety standards that have made it the safest mode of transportation. Yet the very chemicals that enable aviation safety—fire-resistant hydraulic fluids, AFFF foam suppression systems, and surface treatment compounds—contain PFAS that contaminate airport environments and may expose flight crews and ground workers to ongoing PFAS burdens. As aviation regulators and airlines grapple with PFAS transition requirements, the industry faces the challenge of maintaining safety performance while eliminating or reducing PFAS dependence.
Aviation Hydraulic Fluids and PFAS
Aircraft hydraulic systems—controlling flight surfaces, landing gear, and braking systems—use phosphate ester hydraulic fluids that are compatible with PFAS-containing seals, O-rings, and hose linings. The fluoropolymer components in hydraulic system hardware provide chemical resistance to hydraulic fluid and prevent degradation at operating temperatures. While the hydraulic fluid itself is not PFAS-based, the PFAS-containing seals and linings are maintenance items that are regularly replaced and disposed of, creating a small but continuous PFAS waste stream at maintenance facilities.
More significantly, aircraft maintenance facilities use PFAS-containing surface treatment compounds for corrosion protection of aluminum and titanium structural components. Anodizing and alodine processes, as well as chromate conversion coating alternatives that use PFAS-based adhesion promoters, create PFAS-laden process wastewater. Aviation maintenance, repair, and overhaul (MRO) facilities at major airports are significant PFAS discharge points requiring regulatory attention under evolving industrial wastewater standards.
Airport AFFF Contamination: Billions in Cleanup Costs
Commercial airports are among the most intensively AFFF-using facilities outside of military installations. Hangar fire suppression systems, aircraft accident response protocols, and Federal Aviation Administration (FAA)-required fire training programs all historically relied on PFAS-based AFFF. The FAA mandated AFFF use for aircraft rescue and firefighting (ARFF) under federal regulations, effectively requiring PFAS use at every certificated U.S. airport regardless of local environmental preferences.
Groundwater PFAS contamination at airports has been documented at dozens of major commercial airports, with contaminated groundwater plumes extending beyond airport boundaries to affect neighboring residential and commercial properties. Seattle-Tacoma International Airport, Los Angeles International Airport, and Boston Logan Airport are among the facilities where PFAS groundwater remediation programs are underway. The FAA’s 2021 update to ARFF regulations established a transition path to fluorine-free foam alternatives, though aircraft rescue requirements continue to evolve as performance testing of F3 alternatives accumulates.
Flight Crew and Cabin PFAS Exposure
Bleed air—compressed air bled from aircraft engines that is used for cabin pressurization—has been a source of controversy regarding potential chemical contamination of cabin air. When engine oil or hydraulic fluid enters the bleed air system, cabin air fume events (“toxic fume events”) can expose crew and passengers to degradation products of synthetic lubricants and hydraulic fluids, some of which are PFAS-related compounds. PFAS treatment of cabin carpet, seat upholstery, and aircraft interiors represents an additional potential off-gassing source in the enclosed cabin environment. Research into flight crew chemical exposures, including PFAS, is an active area of occupational health investigation.