TUESDAY, July 23, 2002 (HealthDayNews) -- Breathe easier, frequent fliers.
Your risk of catching a cold while traveling is no greater on newer airplanes that recirculate cabin air than in older ones that pump in fresh air from the outside, claims a new study in tomorrow's Journal of the American Medical Association.
Modern jets recycle about half their cabin air as a way to reduce strain on the engines and improve gas mileage. Many older planes, though increasingly obsolete, use 100 percent compressed fresh air to ventilate the seating area.
Studies have shown that poorly ventilated spaces -- such as airplanes and office buildings -- can increase the risk of germ and virus transmission. While airplanes that recirculate their cabin air have fine filters to trap pathogens, experts have wondered if the technology might put passengers at risk of disease by steeping them at least partly in other people's breath.
The answer, according to the latest study, is no.
A research team led by Dr. Jessica Nutik Zitter, formerly an assistant clinical professor of medicine at the University of California, San Francisco, compared rates of colds and other respiratory ailments in 1,100 air travelers going between San Francisco and Denver in 1999. Slightly more than half flew in new jets with air-recycling systems.
Within a week of their trip, 19 percent of the group that had flown on a new plane complained of a cold, compared with 21 percent of the other passengers -- a statistically insignificant difference, the researchers say. Rates of runny nose and cold together -- 10 percent versus 11 percent -- and the strictest definition of illness, a cluster of 8 upper respiratory symptoms (3 percent), were also identical.
Zitter says the 3 percent jibes with the rates of colds in the general population at that time of year, which was January through April. However, she adds, that doesn't necessarily mean that flying carries zero risk of airway infections.
The duration of travel may play a role. The flight from San Francisco to Denver is about 2.5 hours, and it's possible that longer trips may pose more of an infection risk, Zitter says.
"This study was not designed to address the question of whether or not flying for all comers increases your risk of infection regardless of the airplane type" or distance, she says. Only more research, including testing passengers for actual virus encounters, will tell.
Morton Lippmann, an environmental medicine expert at New York University School of Medicine, calls the new findings "nothing really surprising." In newer planes, "infectious agents are not recirculated" because the filters nab them, says Lippmann, chairman of a National Academy of Sciences panel that looked at cabin air quality issues last year.
Passengers may ultimately feel more comfortable flying newer planes because the recycled air is moister than the fresh, dry air in older cabins.(Thank your fellow travelers' perspiration and exhaled vapor for that.) As a result, skin and mucous membranes stay better hydrated in flight.
Air quality on planes can and has become an infection issue when their ventilation systems fail. Still, for the typical passenger, the biggest risk of catching an illness is if the person in the neighboring seat is sick, Lippmann says.
Noal May, an industrial hygienist at the Federal Aviation Administration's Civil Aerospace Medical Institute in Oklahoma City, says research has shown that traveling by air is no more a germ threat than other forms of public transportation, such as buses or trains.
However, "if you're sitting right next to the [sick] individual, your chances of catching something are much greater," May says.
The FAA is currently funding research at the National Institute of Occupational Safety and Health examining the issue of cabin air quality. These include looking at how pathogens move through the chamber and the probability that passengers will fall ill.
What To Do
To find out more about cabin air quality, try the Federal Aviation Administration's Office of Aerospace Medicine or the National Academy of Sciences.
