Risk of nut allergies from air on planes has been overblown

There is no strong evidence that people with peanut allergies are at risk of a severe reaction from others eating peanuts and the allergens circulating through the air while on board a plane. The same is expected to be true for other types of nuts and foods that people are commonly allergic to.

People with food allergies may experience symptoms such as rashes, nausea and breathlessness after being exposed to allergens through eating, skin contact or inhalation. In severe cases, this can cause a life-threatening reaction called anaphylaxis, which can lead to swelling of the throat, dizziness and more serious breathing difficulties.

Some airlines have banned the sale of nuts on flights and their staff make announcements asking passengers not to eat them if they know someone on board has an allergy.

To explore the evidence behind the inhalation risk, Paul Turner at Imperial College London and his colleagues focused on peanuts, reviewing the results of five studies.

One study looked for peanut particles in air samples during a commercial flight where the snack was being served. The researchers found none in nearly all the samples they collected. That is because these aircraft have filters that remove peanut particles in the air before they spread through the cabin, says Turner.

The exception was air samples collected immediately around tray tables where peanuts were being consumed, but these allergens were at such low levels that they would probably be insufficient to cause an allergic reaction, says Turner.

Four other studies looked at airborne allergen levels as people ate or shelled peanuts, either in their homes or a lab. They similarly found very low levels of allergens within about half a metre of someone shelling or eating peanuts. At most, this would cause mild allergic reactions, such as watery eyes, says Turner.

But higher levels of allergens were found on seats, trays and the floor of the first study’s aircraft. Wiping down these surfaces would probably remove much of the risk, says Turner, whose team is working with UK airlines to make flying safer for people with allergies.

The same results would probably apply to other allergens, such as other nuts, seafood and eggs, says Turner.

“This report summarises what has been well established for years, in that peanut is highly unlikely to aerosolise and pose an airborne risk to passengers,” says Matthew Greenhawt at the University of Colorado.