Breathing Easy? The Hidden Risk of Fume Events in Air Travel

When most people fly, they expect cabin air to be clean, or at least safe enough for the duration of the trip. But there is a phenomenon known in the aviation world as a “fume event” that challenges that assumption. How do they occur, what risks do they pose for passengers, and what is the air-travel industry doing (or not) about them?

A fume event happens when the air used to pressurize and ventilate an aircraft cabin becomes contaminated. In many modern jetliners, the air supply originates from the engines, or more precisely, from a system known as bleed air. In simple terms, bleed air is compressed air, heated, then cooled and circulated into the cabin.

If seals or other components fail or leak, engine oil, hydraulic fluid or other fluids may seep into these hot engine sections, vaporize, and mix into the cabin airflow. Passengers and crew may then notice odd smells, sometimes described as “wet dog,” “nail polish,” “dirty socks,” or “burnt” aromas, as well as haze, smoke, or irritation of the eyes, nose, or throat.

How frequently do these events occur during air travel? Exact numbers are difficult to determine, in part because reporting is inconsistent, and many fume events are transient or mild so that they may go unreported. However, studies and safety record analyses provide some insight. One FAA-funded study, conducted from 2007 to 2012, found approximately two fume events per 10,000 flights in the U.S., which translates to several events per day across all airlines.

In Australia, for example, a joint report found over 1,000 incidents of fumes or smoke aboard aircraft between 2008 and 2012; most were minor, though some of those flights were subsequently diverted. More recently, air travel safety news reports suggest that specific aircraft models, particularly those utilizing bleed air in certain configurations, have experienced an increasing number of reported fume events.

What are the health risks? For passengers, most encounters are brief and produce mild effects. For aircrew who frequently fly and are repeatedly exposed, there is greater concern, especially regarding long-term effects. Some studies note that chronic symptoms may include neurological, respiratory or cardiovascular problems. However, the scientific community has not universally agreed on the existence of a formal “aerotoxic syndrome” (a term sometimes used by advocacy groups to describe long-term symptoms following repeated fume exposure). A recent review highlighted that, although acute effects are better documented, evidence for lasting injury remains disputed and less well quantified.

Air travel safety authorities and regulators acknowledge the issue. For example, the U.S. Federal Aviation Administration has released reports on cabin air quality and bleed-air contaminants, estimating the rate of cabin air quality incidents (including fume events) at under 33 per million departures.

Some airlines and manufacturers have undertaken changes in maintenance procedures, improved seal materials, and introduced modifications to better detect or manage air contamination. There are also calls for more consistent reporting, improved cabin sensors to monitor air quality in real-time, and regulatory oversight to ensure standards keep pace with new evidence. Aircraft like the Boeing 787, which use electric compressors rather than bleed air from engines for cabin pressurization, are often cited as examples of alternative designs that may reduce risk.

From the traveller’s perspective, awareness is helpful, and if you notice unusual smells, haze, or feel unwell during a flight, it is worth bringing it to the cabin crew’s attention. Keeping flights relatively short, staying hydrated, and avoiding repeated exposure (as far as possible) are logical steps. In addition, pressing for industry transparency, including improved reporting of fume events and follow-up on passenger health, supports collective safety.