Why We Catch Colds During Flights

Confined Space Most Likely to Blame

Medically Reviewed by Gary D. Vogin, MD

July 23, 2002 -- Get a cold nearly every time you fly? Well, it's not because of the type of air on board. Whether your plane circulates fresh air -- or recirculates cabin air -- doesn't seem to make a difference, a new study shows. More likely, it's the confined space of the aircraft, says one expert.

In recent years, new commercial aircraft have been designed to recirculate approximately 50% of the cabin air to increase fuel efficiency. But it's not been known whether air recirculation increases the transmission of infectious disease.

But some studies have shown higher rates of the common cold among people working in buildings that recirculate air, writes Jessica Nutik Zitter, MD, MPH, a researcher at the University of California, San Francisco. Her paper appears in this week's Journal of the American Medical Association.

In their study, Zitter and colleagues included nearly 1,100 passengers boarding flights on airplanes that had the newer recirculated air systems and on planes that still used fresh air for ventilation. They made follow-up phone calls five to seven days after the flights, asking about symptoms of upper-respiratory infection.

Their findings: Passengers aboard airplanes that recirculated air were more likely to have sinus problems. But as far as the common cold, 21% of passengers aboard fresh-air planes reported colds, compared with 19% of people breathing recirculated air.

The findings suggest that if there is increased risk of common colds among passengers, the main route for transmission is not air recirculation, Zitter writes.

It's the confined space of the aircraft that's probably the main reason why people get colds on airplanes, says Derek Johnson, MD, assistant professor of pediatric allergy and clinical immunology at Temple University Children's Medical Center in Philadelphia.

He agreed to review Zitter's study for WebMD.

"It doesn't matter if you're breathing recirculated or fresh air. If the germs are there, you're going to get sick," he tells WebMD.

Droplets in the air, like when somebody sneezes, are one of the big causes of colds. But touching stuff that people with colds have touched -- like a deck of cards, a newspaper, trays, cups, cans -- counts even more. Touch a cold virus germ, then touch your face, and you've exposed yourself to the virus.

"I don't think people give enough credit to that," he tells WebMD. "People don't realize they touch their face many, many times during the day. It's very easy to transmit those viruses, especially in a confined environment -- whether it's an airplane, an office, or at home."

Also, the stress of travel may lower immunity enough to make you more susceptible, he adds.

To help prevent catching colds, wash hands frequently -- and avoid touching your face.