Can peanut traces linger on airplane surfaces after a flight? Airline snacks raise concerns for passengers with severe peanut allergies. Even tiny amounts of residue could trigger a reaction. You swab seats and tray tables on multiple flights. Armrests get swabbed too. Use sterile swabs and distilled water with phosphate buffered saline. Label each sample carefully and ship them on ice to a laboratory for analysis. The lab tests each swab for peanut protein content. Out of four seats tested, one showed detectable peanut residue at 2.5 parts per million. The other three seats had no detectable amounts. The residue found was too small to cause a severe reaction in most allergic passengers.