Passenger evaluation of the optimum balance between fresh air supply and humidity from 7-h exposures in a simulated aircraft cabin.
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. Maintaining a constant 200 l/s rate of total air supply, i.e. recirculated and make-up air, to the cabin, experiments simulating 7-h transatlantic flights were carried out at four rates of fresh outside air supply--1.4, 3.3, 4.7, and 9.4 l/s per person (3, 7, 10, and 20 cfm/person)--resulting in humidity levels, ranging from 7% to 28% relative humidity (RH). Four groups of 16-18 subjects acted as passengers and crew and were each exposed to the four simulated flight conditions. During each flight the subjects completed questionnaires three times to provide subjective ratings of air quality and of symptoms commonly experienced during flight. Physiological tests of eye, nose, and skin function were administered twice. Analysis of the subjective assessments showed that increasing RH in the aircraft cabin to 28% RH by reducing outside flow to 1.4 l/s per person did not reduce the intensity of the symptoms that are typical of the aircraft cabin environment. On the contrary, it intensified complaints of headache, dizziness, and claustrophobia, due to the increased level of contaminants.


CONCLUSIONS
The investigation shows that increasing aircraft cabin humidity by decreasing the ventilation flow rate of fresh outside air would not decrease reports of discomfort made by cabin occupants.
Strøm-Tejsen
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International Centre for Indoor Environment and Energy, Department of Mechanical Engineering, Technical University of Denmark, Lyngby, Denmark. pst@mek.dtu.dk
Wyon
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DP
Lagercrantz
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Fang
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D000328:Adult; D000368:Aged; D000392:Air Movements; D000393:Air Pollutants / Q000009:adverse effects / Q000032:analysis; D016902:Air Pollution, Indoor / Q000009:adverse effects* / Q000032:analysis; D000401:Aircraft; D002245:Carbon Dioxide / Q000009:adverse effects / Q000032:analysis; D004244:Dizziness / Q000209:etiology; D004784:Environmental Monitoring; D005260:Female; D006261:Headache / Q000209:etiology; D006801:Humans; D006813:Humidity; D008297:Male; D008875:Middle Aged; D009622:Noise / Q000009:adverse effects; D009930:Organic Chemicals / Q000009:adverse effects / Q000032:analysis; D010698:Phobic Disorders / Q000209:etiology; D018877:Sick Building Syndrome / Q000209:etiology; D011795:Surveys and Questionnaires; D013696:Temperature; D014691:Ventilation
D000393:Air Pollutants; D009930:Organic Chemicals; D002245:Carbon Dioxide