A comprehensive review published in the Archives of Disease in Childhood challenges the widely held belief that nut allergens can be transmitted through aircraft ventilation systems. According to allergy and aviation medicine specialists, the primary risk arises from allergen residues on surfaces, such as tray tables and seat-back video screens, particularly during the fast turnaround times typical of many low-cost carriers.
The review indicates that allergic reactions to food are significantly less common during flights—estimated to be 10 to 100 times less frequent than on the ground. This disparity may stem from heightened precautions taken by food-allergic passengers when flying, the authors suggest.
In the UK, approximately 2–3% of children and 1–2% of adults are affected by food allergies, with similar prevalence rates reported in medium to high-income countries. Food allergies are the leading cause of anaphylaxis, a severe and potentially life-threatening allergic reaction.
To address misconceptions surrounding the risks posed to passengers with food allergies on commercial flights, the authors conducted a systematic review of published evidence dating back to 1980, commissioned by the UK’s Civil Aviation Authority (CAA) in 2023. They found that allergic reactions to aerosolized foods are rare and often not reproducible, with the notable exceptions of vapors from seafood and occupational exposure to wheat flour.
While peanut allergens can be detected in the air when shelling nuts, this dust settles quickly and is only detectable close to the source, indicating minimal circulation of allergenic dust throughout the cabin. The aircraft’s ventilation systems are designed to circulate air efficiently across the cabin, reducing the likelihood of spreading contaminants.
Air in the cabin is completely exchanged every 3–4 minutes during a flight, significantly faster than the 10-minute exchange rate in hospitals and classrooms. Modern commercial aircraft recirculate about half of the air intake, which has passed through particulate air filters designed to eliminate dust, vapors, microbes, and aerosolized food particles.
The authors emphasize that food proteins tend to be “sticky,” with unintentional exposure primarily resulting from surface contamination on seats and tray tables. This contamination can occur when food allergens transfer from hands to food or directly to the mouth and face.
To mitigate these risks, the authors recommend cleaning surfaces at the beginning of each flight with sanitizing wipes, particularly as minimal cleaning often occurs between flights, especially on low-cost carriers. Allowing food-allergic passengers to pre-board could further reduce risks, a practice already mandated by the U.S. Department of Transportation for airlines accommodating nut allergies.
However, the authors caution that announcements requesting passengers refrain from consuming nuts during flights may not significantly reduce in-flight reactions and could create a false sense of security. Many food-allergic passengers prefer to bring their own food, but most airlines offer allergen-free meal options if requested in advance.
The review also advises that passengers at risk of food anaphylaxis should carry adrenaline auto-injectors, such as EpiPens, in their hand luggage, as these are not always included in onboard medical kits, and cabin crew may not be permitted to use them.
In conclusion, the authors state, “There is no evidence that peanut or tree nut allergens are spread through aircraft cabin ventilation systems. Instead, the primary risks arise from either dietary avoidance failures or allergen residues on surfaces, exacerbated by the rapid turnaround times of many low-cost carriers.” They advocate for airlines to establish clear, accessible policies regarding food allergies that are consistently applied by ground and cabin staff to reassure passengers and their caregivers.
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