Can Aerosolized Nut Particles on a Plane Really Cause an Allergic Reaction?

One of the misconceptions about food allergies during air travel is that aerosolized nut particles circulate in the aircraft ventilation system and pose a significant risk, which could be mitigated by “nut bans,” according to an evidence review.

Contrary to this common belief, allergic reactions during commercial air travel are actually 10 to 100 times less common than those on the ground, probably because of the extra precautions taken by those with food allergies when traveling, noted Paul Turner, PhD, of Imperial College London, and Nigel Dowdall, MSc, MBChB, of Aviation Medical Consultancy Limited in Burgess Hill, England.

What’s more, reactions to aerosolized foods are “very uncommon and rarely reproducible,” they wrote in Archives of Disease in Childhood.

“Research studies (including aircraft simulations) show no evidence to support airborne transmission of nut allergens as a likely phenomenon,” they reported. “Announcements requesting ‘nut bans’ are not therefore supported, and may install a false sense of security.”

Still, food allergies are the leading cause of anaphylaxis, and vacations and travel can be extra challenging, Turner and Dowdall acknowledged.

They pointed to a survey showing that food-allergic passengers reported unprofessional and insensitive behavior from airport and airline staff, including being asked for medical notes and having epinephrine autoinjector devices confiscated. These experiences could contribute to perceptions of increased risk of allergic reactions on planes, the authors said.

As for nut particles commonly causing allergic reactions after being transmitted through the aircraft ventilation system, Turner and Dowdall noted that airborne peanut allergens are only detected at low levels when roasted peanuts are being shelled, and only very close to the nuts. Aircraft ventilation systems circulate air across the cabin rather than along it, and exchange the air in the cabin completely every 3 to 4 minutes.

In addition, “HEPA filters used on commercial aircraft have a particle-removing efficiency of 99.97% at 0.3 µm, which effectively remove dust, vapors, potential microbial pathogens, and capture the vast majority of aerosolized food particles at the same time,” they wrote.

A more likely risk, according to the authors, are errors in food avoidance — for example, when food-allergic passengers purchase what they believe to be “safe” food and ingest their allergen accidentally. Another is the transmission of residue from seat/tray surfaces, including screens on seat backs, to a person’s hands, which can then lead to a food being consumed — a risk that can be reduced by allowing passengers with peanut and tree nut allergies to pre-board and wipe surfaces.

“Imagine being in a metal box 30,000 feet above the ground and away from healthcare and having a life-threatening food allergy with a couple hundred people around you eating your allergen,” said Scott Sicherer, MD, of the Icahn School of Medicine at Mount Sinai in New York City, in an email to MedPage Today. “Imagine a young child with a food allergy who is bored on the flight and will be rubbing all over her seat and crawling to the floor and might find some leftover foods from a seat crack she might put in her mouth.”

“The article discusses wiping off seats, tray tables, etc. I would add, for a young child’s seat, to also check in the cracks for any food they might ‘find’ and taste,” added Sicherer, who was not involved in the study. He also noted that airline-prepared meals are “not typically covered by labeling laws and caution is advised.”

Apart from cleaning one’s area, Turner and Dowdall said bringing food to eat while flying is an effective prevention method. They also noted that for those who have prescribed autoinjector devices, a medical note is not required, and two doses should be carried on the plane — airlines may not always stock adrenaline in first aid kits.

For this evidence review, the authors summarized findings from a systematic review of literature commissioned by the U.K.’s Civil Aviation Authority, which included studies from 1980-2022 related to risks to food-allergic individuals on commercial flights, and how these risks might be mitigated.

Please enable JavaScript to view the comments powered by Disqus.