To assess the prevalence of immunoglobulin E–mediated peanut allergy to airborne peanut protein and quantify the peanut protein present in the surrounding air.

A total of 84 peanut-allergic children referred to an airborne peanut challenge at Sachs’ Children and Youths Hospital were included. The majority (74%) had a history of an allergic reaction to peanut; 26% had positive test results, with no reaction history.

This was a retrospective case series. Children underwent an airborne challenge to either roasted peanuts or dry roasted peanuts 50 cm in distance away, with 30 minutes exposure time, followed by 1 hour observation postexposure. Patients were examined at baseline and every 10 minutes during the challenge. Electrostatic filter devices were used to collect aerosolized peanut protein and protein was detected by using the enzyme-linked immunosorbent assay. Measured amounts in air samples were used with confirmed peanut-allergic patients’ serum for basophil activation tests to assess in vitro if such miniscule amounts could trigger activation of basophils.

No child in the study experienced anaphylaxis to airborne peanut allergens, and 98% revealed no signs or symptoms of peanut exposure; 2% of patients experienced mild symptoms, consistent with oral itch and rhino conjunctivitis. Peanut protein was detected in a low amount (comparable to the amount that can trigger a reaction in the 5% most sensitive patients) at 0 m distance from the bowl of peanuts. Detectable peanut protein was dramatically reduced when moving short distances (0.5 m) from the box of peanuts. Prolonging the exposure time of the filter did increase the peanut protein concentration that was detected.

Severe reactions to airborne peanut protein were not observed in this study, and the majority of patients were asymptomatic. Peanut protein was confirmed in surrounding air and was also shown to be able to activate basophils in vitro at comparable concentrations. However, on the basis of the clinical data, these concentrations of proteins are not expected to lead to significant clinical reaction.

Allergic reaction to airborne peanut protein is often a fear and source of anxiety for peanut-allergic patients and their parents. This study is reassuring that airborne exposure to peanut protein is low risk for occurrence of a severe reaction. These findings could be helpful when counseling patients about risks while trying to minimize unnecessary anxiety or activity restrictions.