My husband and I often get colds and respiratory infections on vacations. Some say the reason for this is that airlines save fuel by minimizing the amount of fresh air circulated through cabins. Is there any standard for fresh air circulated during a flight?
Almost everyone who falls sick after flying wonders whether a coughing, sneezing fellow passenger is to blame. The answer, experts say, may be yes - but the conducting culprit is not recirculated air; it's proximity, bad luck and poor hand-washing, the same elements to blame for virus transmission on the ground.
The Federal Aviation Administration regulations state that an airliner's ventilation system must be designed to provide each occupant with at least 0.55 pounds of fresh air per minute. That's about 10 cubic feet of air a minute. On a typical passenger jet, the ratio of fresh to recycled air is about 50-50.
Most experts agree that the recirculated air poses little or no threat to health as long as the aircraft is equipped with a high-efficiency particulate air filter. According to a 2004 report by the Government Accountability Office, 85 percent of major commercial airlines used HEPA filters on aircraft designed for 100 or more passengers. But the filters, which are not mandatory, were far less common on smaller regional jets.
The current medical literature supports the notion that the aircraft cabin ventilation system actually minimizes the spread of infection, said Dr. Mark Gendreau, a senior staff physician at the Lahey Clinic in Burlington, Mass. But even fresh air and filters can't protect passengers from exposure to someone with the flu in the same row or to viruses and bacteria on an escalator handrail.