The effects of the aircraft cabin environment on passengers during simulated flights

A 3-row, 21-seat section of a simulated Boeing 767 aircraft cabin has been built in a climate chamber, simulating the cabin environment not only in terms of materials and geometry, but also in terms of cabin air and wall temperatures and ventilation with very dry air. This realistic simulation enables subjective assessments of the symptoms commonly experienced by passengers and crew during flights. Six investigations with subject exposure have subsequently been carried out in the aircraft cabin facility covering four environmental areas of study, i.e. humidity, air purification techniques, ozone, and thermal effects. The humidity study, examining the optimum balance between fresh air supply and humidity, showed that increasing relative humidity in the aircraft cabin by reducing outside air flow did not reduce the intensity of symptoms typically experienced in the aircraft cabin but intensified complaints of headache, dizziness and claustrophobia, suggesting that air pollutants rather than low humidity cause the distress reported by airline passengers. Three investigations studying the efficacy of various air purification technologies showed that a gas phase adsorption purification unit performed better than two different photo-catalytic oxidation units, although all three units greatly reduced the concentration of air pollutants in the cabin. Results obtained from the Ozone investigation indicate that the presence of ozone in the aircraft cabin is a principal cause of a number of the symptoms commonly associated with the aircraft cabin. It suggests that it would be beneficial to remove ozone at levels less than currently specified. The last study, investigating the influence of air temperature on passenger comfort and symptoms, showed that cabin air temperature affected the perception of air quality, air freshness, and thermal sensation, improving these perceptions when temperature was lowered.