Peanut and tree nut allergies are not disseminated via airline cabin ventilation arrangements but through accidental dietary ingestion of allergens or their residues on seat surfaces.
A recent review in Archives of Disease in Childhood presents common misconceptions regarding food allergies during air travel and discusses strategies to help prevent them.
Background
Food-allergic passengers feel heightened anxiety while flying due to the perceived risk of peanut or tree nut particle exposure through airplane ventilation systems. Food allergies can result in anaphylaxis, a life-threatening allergic response. Fear of severe responses lowers quality of life, particularly during holidays and travel. Dispelling myths about air travel-related food allergies could increase confidence among food-allergic individuals.
About the review
The present review discusses myths and evidence regarding in-flight food allergies and mitigation strategies based on the 2023 United Kingdom Civil Aviation Authority (CAA) report.
Common myths and evidence regarding food allergies during air travel
Myth 1: Allergic responses are more frequent on airplanes
The evidence: Research shows that individuals with food allergies are 10 to 100 times less likely to develop allergic reactions on a flight. The low frequency of allergies among food-allergic passengers may be attributed to the measures taken when flying.
Myth 2: Aerosolized food allergens are a major concern
The evidence: Allergies to aerosolized meals are infrequent, except for exposure to vapors from fish or seafood or occupational allergens such as wheat flour in baker’s asthma and seafood in fish market workers.
Myth 3: Peanut particles in ventilation systems trigger reactions
The evidence: Individuals with food allergies think peanut particles may transfer through aircraft passenger cabin ventilation systems and induce allergic responses. However, such occurrences are rare. Deshelling roasted peanuts can produce low-level but detectable peanut allergens in the air. However, aircraft ventilation systems successfully remove most nut particles in circulation. Allergies most likely result from the unintentional eating of allergen-containing food and the spread of allergen residues from seat or tray surfaces to hands, subsequently transferred to safe food ingested.
Myth 4: Nut consumption bans prevent in-flight allergies
The evidence: People think requesting passengers not to consume nuts can prevent in-flight nut allergies. However, peanut residues on seats from prior flights cause significantly more exposure than nut-eating on a current flight. Cleaning seat surfaces, tray tables, and seat-fixed entertainment systems with wet wipes before beginning flight travel is far more effective in reducing allergy risk. Nut ‘bans’ might sometimes lead to false reassurance.
Myth 5: Homemade food is safer than airline meals
The evidence: Individuals with food allergies frequently avoid airline meals and carry homemade food. However, food allergies on a flight occur after consuming homemade food and items purchased on flights, typically due to human errors in buying items that may contain allergens. Airlines frequently provide allergen-free meals if informed in advance.
Myth 6: Medical authorization is required to carry adrenaline injectors
The evidence: Individuals assume medical authorization is necessary to transport adrenaline injectors on an airplane. However, UK legislation permits individuals prescribed adrenaline autoinjectors to carry them without such restrictions.
Onboard medical tool kits rarely include autoinjectors, and cabin crew members may not always have permission to use autoinjectors. Thus, food-allergic passengers with anaphylaxis risk should carry two adrenaline injectors in cabin baggage with them when flying.
Air circulation systems for passenger cabins on commercial planes
Environmental control systems (ECS) in airplanes regulate cabin air pressure, supply, and temperature to provide passengers and cabin crew with a pleasant atmosphere. The systems assure the removal of carbon dioxide, smells, and other airborne impurities, necessitating high airflow rates throughout the cabin. Air enters the cabin from overhead distribution outlets in a regulated circular airflow pattern. The pattern causes air to circulate throughout the aircraft, limiting the spread of pollutants.
ECS delivers approximately 20 cubic feet of air per minute per passenger, resulting in a full cabin air exchange every three to four minutes. In commercial airplanes, over 50% of the air intake is recirculated air passed through high-efficiency particulate air (HEPA) filters. HEPA filters remove 99.97% of particles at 0.3 µm, including dust, vapors, and microbiological diseases. They also capture the majority of aerosolized food particles. HEPA filtration and the frequency of full cabin air exchange (15-20 times per hour) lower peanut residue in dust suspended in cabin air.
Conclusions
Based on the findings, peanut and tree nut allergies are not disseminated via airline cabin ventilation arrangements but through accidental dietary ingestion of allergens or their residues on seat surfaces.
Announcements recommending that passengers avoid nuts may not prevent in-flight responses. Cleaning sitting places with a moist wipe is an excellent method.
Airlines must have defined food allergy-related policies mentioned on their websites and routinely followed by cabin crew and ground workers.
‘Buffer zones’ in which passengers surrounding a food-allergic traveler are urged not to consume the allergen may give reassurance but pose concerns about which allergens other passengers can be asked not to ingest.
