The study tested for many of the same contaminants measured when evaluating a building's indoor air quality, including carbon monoxide, ozone, respirable particulates, bacteria, fungi and volatile organic compounds. Levels of carbon dioxide, cabin altitude, relative humidity, noise and temperature were also measured. Flight attendants complained frequently about the cabin's low humidity. But, he said, this did not rule out unusual problems on individual aircraft or flights. He pointed out, for example, that aircraft flying the North Atlantic route at certain times of the year could encounter a higher level of ozone coming in with the bleed air.
Ozone can act as an irritant, burning eyes and throats.
Dr. Russell Rayman, executive director of the Aerospace Medical Association that specializes in the physiology of flight, said that post-flight illness may be caused not by contaminants but by factors such as jet lag, lack of mobility, the lower oxygen content of pressurized cabins, vibration, poor air pressure control or psychological stress. But there is concern if an engine is not working well, needs an overhaul or has a leak, it could pick up a contaminant that is heated as it bypasses the engine. In testimony before a Washington State Senate labor committee last month, flight attendants for Alaska Airlines reiterated their complaints of unusual odors, noxious fumes or smoke or ''mists'' at times in aircraft cabins. Their health complaints included nausea, dizziness, blurred vision or disorientation. The union representing the flight attendants, the Association of Flight Attendants, has recently suggested these incidents correlate with mechanics' records of hydraulic fluid and lubrication oil refillings.