OCCUPANT EVALUATION OF 7-HOUR EXPOSURES IN A SIMULATED AIRCRAFT CABIN - PART 1: OPTIMUM BALANCE BETWEEN FRESH AIR SUPPLY AND HUMIDITY

ABSTRACT Low humidity in the aircraft cabin environment has been identified as a possible cause of symptoms experienced during long flights. A mock-up of a 21-seat section of an aircraft cabin with realistic pollution sources was built inside a climate chamber, capable of providing fresh outside air at very low humidity. Experiments simulating 7-hour transatlantic flights were carried out at four outside air supply rates - 1.4, 3.3, 4.7 and 9.4 L/s per person (3, 7, 10 and 20 cfm/p) - yielding average humidity levels of 28%, 16%, 11% and 7% RH, respectively. Four groups of 16-18 subjects were exposed to the four conditions. The subjects completed questionnaires to provide subjective assessments of symptoms commonly experienced during flights. Increasing humidity to 28% RH by reducing outside air supply rate did not reduce the intensity of the symptoms typical of the aircraft cabin environment, and intensified headache, dizziness and claustrophobia. INDEX TERMS Aircraft cabin air quality, Low humidity, Passenger comfort, Sick building syndrome (SBS) symptoms, Ventilation requirements