Context In recent years, new commercial aircraft have been designed to recirculate
approximately 50% of the cabin air to increase fuel efficiency. Some older
aircraft use only fresh air. Whether air recirculation increases the transmission
of infectious disease is unknown; some studies have demonstrated higher rates
of the common cold among persons working in buildings that recirculate air.
Objective To evaluate the role of air recirculation as a predictor of postflight
upper respiratory tract infections (URIs).
Design, Setting, and Participants A natural experiment conducted among 1100 passengers departing the San
Francisco Bay area in California and traveling to Denver, Colo, during January
through early April 1999, and who completed a questionnaire in the boarding
area and a follow-up telephone interview 5 to 7 days later. Forty-seven percent
traveled aboard airplanes using 100% fresh air for ventilation, and 53% traveled
aboard aircraft that recirculated cabin air.
Main Outcome Measure Incidence of reporting new URI symptoms within 1 week of the flight.
Results Passengers on airplanes that did and did not recirculate air had similar
rates of postflight respiratory symptoms. The rates of reporting a cold were
19% vs 21% (P = .34); a runny nose and a cold, 10%
vs 11%, (P = .70); and an aggregation of 8 URI symptoms,
3% in both groups (P>.99). Results were similar after
statistical adjustment for potential confounders.
Conclusion We found no evidence that aircraft cabin air recirculation increases
the risk for URI symptoms in passengers traveling aboard commercial jets.