Planes, Trains, and …Germs?
Travel Health Risks You Can -- and Can't - Avoid
Up in the Air, Germs Are There continued...
There's a lot we don't know, agrees Roy L. DeHart, MD, MPH, senior consultant in occupational and aviation medicine at Vanderbilt University, Nashville, Tenn. And if anyone understands the various health risks of flying, it's DeHart. He capped his 23-year Air Force career as commander of the USAF School of Aerospace Medicine. Former director of occupational and environmental Medicine at the University of Oklahoma, he's an FAA-certified senior aviation medical examiner.
"We don't know what that passenger next to you is contributing to the air stream as he is inhaling and exhaling," DeHart tells WebMD. "With flights coming out of developing countries where prevention programs are not as strong as they might be, it is not unusual that a person may have a problem like tuberculosis. It spreads. Usually just to two or three people, but if a patient is found on board, health authorities have a tough job trying to track those people down. It can be a horrendous problem. There can be hundreds of patients spreading whatever, wherever. Major spread is possible. So, yes, there can be problems."
Which Is Healthier: High-Flying Planes or High-Rise Offices?
Air passengers often complain about aircraft ventilation. But Gendreau notes that a normal airplane cabin changes its air 15 to 20 times an hour. A typical office building changes its air 12 times an hour.
High efficiency particulate air (HEPA) filters scrub the air on some planes. The filters may be able to trap airborne viruses because they catch the droplets that carry the viruses. But 15% of U.S. commercial airliners carrying more than 100 passengers lack HEPA filters.
"Federal regulatory agencies need to tighten the rules in terms of ventilation and in terms of the HEPA filters that are used," Gendreau says. "Now, in the U.S. and Europe, there are no requirements for how much ventilation an aircraft should have. They don't specify what kind of HEPA filters to use - or even require them."
Even so, there's no definitive proof linking airplane ventilation to disease spread. Overall, the risk of catching something from another infected passenger is about 1 in 1,000 -- about the same as an office building or any other confined space. And Gendreau points out that mathematical models indicate that doubling a plane's ventilation rate would cut the risk of airborne infection by half (using tuberculosis as a model).