Cabin Fume Events Continue to Take Their Toll on Passengers and Flight Crews

On September 19, 2026, several passengers on Delta Flight 394 from Kahului, Hawaii, to Seattle, Washington, had to be rushed to the hospital after fumes filled the cabin of the A321neo shortly after takeoff. They complained to the flight attendants about experiencing nausea and headaches, prompting the pilots to declare an emergency and divert to Daniel K. Inouye International in Honolulu, where first responders met the aircraft.

Air Canada Rouge Flight 1833, an A319 flying from Antigua to Toronto, Ontario, on November 15, 2025, experienced a severe air-contamination event and had to divert to Punta Cana, Dominican Republic. The Transportation Safety Board of Canada later reported that the fumes affected several flight attendants, with one becoming unresponsive during taxi-in after landing.

Air-quality events continue to pose a very real threat to aviation safety. They can affect pilot performance and produce serious health consequences for all those exposed. Reports of these occurrences have been documented since the 1950s and have significantly increased over the years, although some have likely gone unreported.

“While we’ve been making progress helping our industry facilitate open discussions around research, education, standardized reporting, and data collection of air-quality incidents aboard aircraft, it’s time to address these serious events and start protecting passengers and crews from toxic fumes,” observed Capt. Jason Ambrosi, ALPA’s president. “For too long, the underlying causes have gone unaddressed.”

What’s That Smell?

All airliners, except for the B-787, rely on bleed-air systems for cabin ventilation, which draw outside air through engine compressors and mix it with recirculated cabin air to allow for both breathing and pressurization. Only the recirculated air is filtered, and, even then, toxic chemicals from anti-wear additives in heated engine oil, hydraulic fluid, and other synthetic lubricants can leak into this vital air supply.

Changes in bleed system pressure, overservicing, or a component failure in the engine/auxiliary power unit (APU) can disrupt seal performance causing pyrolyzed oil or fluid to leak. The result can be invisible noxious odors or, in some instances, visible smoke or haze permeating the cabin air.

...physicians have compared the effects on the brain in severe fume cases to concussions experienced by professional football players.

Thousands of incidents have been reported since 2010. Air-quality events commonly occur at the gate when the APU is running, after starting the engine, during takeoff and initial climb, and during descent. The APU can be the initial source of the contamination in flight even though it’s not running.

Oil fumes are often musty smelling, sometimes described as a “dirty sock” odor, while hydraulic fluid fumes typically have an acrid scent. Various thermally decomposed, volatile organic compounds can cause hypoxia with symptoms such as headaches; sinus, eye, or respiratory irritation; and reduced reaction times.

Health Risks

On August 10, 2017, a flight attendant on JetBlue Flight 19 from Boston, Massachusetts, to San Diego, California, notified the pilots of a strange odor from the aft galley. The flight attendant reported feeling dizzy and had a headache and mentioned that some of the passengers had complained about the smell. The pilots contacted air traffic control, requesting a diversion to Buffalo, New York. Once on the ground, a pilot and two flight attendants were taken to a nearby hospital, and others were medically assessed at the airport.

Health risks from exposure to contaminated air can result in a host of symptoms ranging from headaches and dizziness to more significant injuries, such as respiratory problems and neurological issues, including damage to the central nervous system. In fact, physicians have compared the effects on the brain in severe fume cases to concussions experienced by professional football players.

Nearly a decade ago, an ALPA member confronted a career-ending air-quality event. He initially experienced coughing and a headache and, at one point, reportedly fell down a jetway. It was later determined that the aircraft’s APU was leaking oil, contaminating the airplane’s environmental control system.

The pilot was diagnosed with toxic encephalopathy. Symptoms of this disorder can include confusion and disorientation; memory loss and trouble focusing; personality or behavioral changes; muscle weakness, tremors, or involuntary twitching; and seizures or loss of consciousness in severe cases.

Two years later, the pilot’s employer denied the case’s compensability (i.e., the legal or financial capacity of an injury, illness, or loss to qualify for compensation), rejecting that he suffered from the disorder. However, a state workers’ compensation board sometime later ordered that the airline’s denial of the claim be “set aside.” The board specified that the pilot should receive a 25% penalty award for the denial and be recompensed for a variety of other expenses.

Fuming at the Federal Level

While Transport Canada regulates aviation safety, no specific federal regulations mandate real-time chemical air monitoring on board airliners in Canada, nor is there a dedicated regulatory definition for a “contaminated air” or “fume” event. The industry relies on general airworthiness standards, mandatory mechanical reporting, and voluntary, nonpunitive safety-reporting programs to evaluate these kinds of events to determine any corrective action.

In the United States, airlines are required to file service difficulty reports when an accumulation or circulation of smoke, vapor, or toxic/noxious fumes occurs in the aircraft, but only during flight. Occurrences on the ground aren’t required to be reported, and gaps in reporting exist if a defect or malfunction hasn’t been found.

In addition, Section 362 of the FAA Reauthorization Act of 2024 outlines a voluntary reporting system for airline employees to document air-quality events and the specific flights on which they occurred. However, these measures don’t fully address the problem, and more action is needed.

Pending Legislation

With ALPA’s full backing, U.S. Sen. Richard Blumenthal (D-CT) and U.S. Rep. John Garamendi (D-CA), a senior member of the House Committee on Transportation and Infrastructure, introduced the Cabin Air Safety Act of 2026, bicameral legislation to protect airline pilots, flight attendants, and passengers from air-contamination incidents on aircraft.

The bill takes several important steps to address fume events by establishing mandatory training for flight crews, first responders, and aviation technicians. These actions include requiring the FAA to investigate reported air-contamination occurrences in the case of serious medical incidents involving passengers or crew and creating standardized reporting with a public portal to ensure transparency.

If enacted, the legislation would also require the FAA to develop cabin air-quality standards and maintenance requirements. Air carriers would be mandated to install monitoring equipment on aircraft. Plus, the bill would help ensure that the FAA works collaboratively with both its industry and labor partners as part of the process to address this safety-critical concern.

What ALPA Members Should Do

If you experience an air-contamination event, always follow your company’s published procedures, seek medical attention, and review and follow the steps in ALPA’s Fume Exposure Guidance.

Members with additional questions should contact ALPA’s Engineering & Air Safety Department at EAS@alpa.org or 800-424-2470.