Many U.S. airlines have stopped serving or selling peanuts as onboard snacks.
Passengers with allergies to tree nuts may face lower risks of encountering allergens onboard commercial aircraft than previously understood, according to a new study by the British Medical Association.
The study, commissioned by the U.K.’s Civil Aviation Authority (CAA) to explore risks posed by flying to passengers with food-related illnesses and how those risks might be mitigated, ultimately suggested that food-related allergic reactions are 10-100 times less common onboard commercial aircraft than they are on the ground. The study suggests that the precautions taken by food-allergic passengers while flying, which are generally more stringent than everyday situations, are contributory, but also that there is “no evidence” that airborne transmission of nut allergens inflight is “a likely phenomenon.”
The study also noted that there’s a perception that passenger reactions to aerosolized peanut dust is common, so it conducted experiments to determine the risk of peanut dust to passengers in flight. The experiment enlisted peanut-allergic children in a double-blind, placebo-controlled challenge where peanut butter was held near their face for several minutes. Another experiment put a bowl of peanuts in front of the peanut-allergic child in a confined space to simulate an aircraft cabin, shaking the bowl periodically to stir up peanut dust.
The experiments found that only two out of 84 children with a bowl of peanuts placed in front of them in an aircraft-like environment experienced mild symptoms that did not require further treatment. The study notes that peanut butter and already shelled peanuts produced little to no aerosolized peanut dust, and that shelling peanuts produces more detectable amounts of peanut allergen, but only briefly, and it tends to settle back down into the bowl rather than disseminating in the surrounding air.
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The study authors suggest that “nut bans” are unnecessary to preserve the safety of travelers with nut allergies, and that the most likely danger posed onboard is from tray tables, seats, and entertainment surfaces. They further suggest that announcements for passengers in the vicinity of those with nut allergies not to consume nut products are also unhelpful, as they might provide false reassurance that the environment is free from allergens.
Passengers with nut allergies, they say, should be permitted to preboard to wipe down their seats, and should carry a supply of two epinephrine devices on their person when traveling. The authors also suggest airlines should carry backup epinephrine auto-injectors for emergencies—a practice not yet universal among U.S. air carriers.
The study also reviewed aircraft ventilation systems, and found that the HEPA filters present in onboard air circulation systems effectively remove any aerosolized nut dust or particles. Their findings were direct: “There is no evidence that peanut or tree nut allergens are spread through aircraft cabin ventilation systems.”
Many U.S. airlines have stopped serving or selling peanuts as onboard snacks, although some still serve other nuts less prone to aerosolization, like almonds and cashews. Most airlines will also allow passengers with nut allergies to preboard to clean their immediate seating area, and some who serve nuts onboard will stop serving them in the vicinity of a passenger who informs the airline of their allergy. US carriers won’t, however, guarantee allergen-free flights, and many won’t request other passengers not eat or bring nuts onboard. Airlines that will request other passengers not eat nuts onboard note that they cannot prevent them from doing so.
U.S. carriers also request passengers with nut allergies travel with their own supply of epinephrine should they have an allergic reaction while onboard. Epinephrine is required to be in U.S. carriers’ emergency medical kits, but not in the auto-injector form used for treating allergic reactions.
Many U.S. carriers also recommend that passengers with nut allergies discuss the risks of traveling with their physician.
The study notes that 2-3% of children and 1-2% of adults in the United Kingdom have a food allergy, a rate similar to other medium-high-income countries. Nearly all those surveyed with food allergies reported increased anxiety when flying, and a third reported “unprofessional or insensitive behavior” from airline workers regarding their allergies.
