The specialists in allergy and the aviation medicine, in a review published in the Archives of Disease in Childhood, argue that the prevalence of nut allergies in flight is an unfounded fear as there is no data supporting it.
The primary source of potential harm is likely to be residual allergens on high-contact surfaces such as tray tables and the in-flight seatback screens, with the added risk exacerbated by the quick processing times that many no-frills airlines utilize, they propose.
And they further explain that allergic reactions to allergens from food sources are at least 10 to 100 times rarer during flights compared to “when one is on the ground”. However, this may be because fear of allergen exposure forces food allergic passengers into stricter behavioural modification while flying.
The authors state that food allergy prevalence among children and adults in the United Kingdom stands at approximately 2-3% and 1-2%, respectively. similar rates are seen in upper middle-class and developed nations. The highest number of anaphylactic reactions are reported due to this label.
In order to clarify some of the myths that surround food-allergic passengers on board commercial flights, the authors relied on a comprehensive and systematic review of the evidence published since its founding in 1980 commissioned by the UK Civil Aviation Authority (CAA) in 2023.
Except for the exposure to steam of fish/seafood and occupational exposure to wheat flour allergic responses to foods in aerosol form are very uncommon and hard to induce, the authors explain.
When peanuts are shelled, this allergenic substance can be found in the atmosphere up and about at very low levels, but as the nut dust clouds, such levels of activity can only be detected a few inches from the object suggesting that little nut dust particles ever get airborne.
In addition, the authors clarify, the cabin air distribution systems in the airplanes are constructed to move the air across the aircraft but not to the cabin hence reducing the chances of airborne passenger-borne pollutants moving through the cabin.
Even during the flight, the air in the aircraft is replaced after every three to four minutes.
This is more frequent compared to 10 minutes in hospitals and classrooms. The modern large commercial airliner also recirculates about half of the air intake which has passed through the particulate air filter that removes dust, vapors and microbes while at the same time capturing food aerosols. The remaining half is drawn from the outside.
Most food allergens or food proteins have a property of being ‘sticky’ therefore making it easy for one to unknowingly get exposed through surfaces which are contaminated such as the ones located in the back of seats, the entertainment systems installed in the seats, as well as on the tray tables. This could have been transferred by hands to morsels of food being consumed, or the mouth and/or face directly.
The authors note that if these areas are wiped down using sanitizer wipes at the beginning of the flight, the risk will be reduced and it is “very relevant due to the lack of cabin turnaround cleaning that most times occurs between flights, particularly with budget airlines.”
Pre-boarding food-allergic passengers may help in this case, write the authors, pointing out that the US Department of Transportation already requires that airlines allow such passengers pre-board in the event of a nut allergy.
But calling for passengers to avoid eating nuts during the flight is unlikely to mitigate the chances of in-flight allergic reactions, and could offer false sense of security, the authors add.
Most of the passengers with food allergies when travelling prefer carrying food from outside, however where in-flight meal service is available most airlines provide options without the allergens upon prior request.
Also, they advise, passengers who are at risk of food anaphylaxis carry auto-injectors of epinephrine such as EpiPen in their hand baggage, because they are not always provided in the onboard medical kits, nor are the crew permitted to use them.
“Aircraft cabin ventilation systems are not conducive for the dispersion of peanut or tree nut allergens. Rather, the risks arise either through cross-contamination resulting from ingestion of banned foods or direct contact with the allergen, which is worse due to the very minimal turnaround of many no frills airlines”, the authors conclude.
“Airlines need to have food allergy-related policies which should be easily accessed on their websites or upon request. These policies should be enforced without exception by ground personnel and airline staff in order to reassure passengers suffering from food allergies and their guardians”, they conclude.
Reference: Flying with nut and other food allergies: unravelling fact from fiction, Archives of Disease in Childhood (2024).
