Do Germs Spread on Airport Security Lines?

We live in a germy world, says William Schaffner, infectious-disease specialist and chairman of the Department of Preventive Medicine at the Vanderbilt University School of Medicine in Nashville, Tenn. "If we went down to Times Square and began culturing people's noses, something like 10% to 20% of them carry the antibiotic-resistant staph infection MRSA," he adds.

For the most part, however, those bacteria are harmless since we all have immunities against them. Simple hygiene—showering, washing hands—"will keep the bad guys at bay," he says.

Same goes for the barefoot march through airport security. The risk of catching athlete's foot or another fungus from fellow travelers is very low.

"It's in prolonged dampness that a toe fungus can get a foothold, so to speak," says Dr. Schaffner. "So unless you're in the middle of a monsoon and the airport has flooded, you're not going to be sloshing through a sea of water and spreading foot germs." Even in the humid month of August, when sweaty feet traipse through airport security, the area is essentially a dry environment.

Still worried? Wear socks, "not sandals or flip-flops that oblige you to go barefoot through security," he says. Should your fashion sense not permit socks, then wipe your feet with disinfecting cloths after security—"although I travel quite a bit and have never seen anyone do that," he says.

Those dirty bins—where you might set your mobile phone in the same spot a road warrior just put his smelly shoes—may carry some of the typical bacteria circulating around us, but again, the risk of infection is likely to be very low.

"There is nothing in the medical literature about catching hand, foot and mouth disease or anything else from airport security," Dr. Schaffner says.

If you're one of those people who considers wearing a face mask on long-haul flights, he adds, bring a pack of disinfecting wipes or sanitizing gel and slather some over your phone before putting it to your face.

Just don't overdo it. Covering yourself in hand sanitizer and wiping down everything that comes into contact with other humans is not only impractical, it may work against you, says Dr. Schaffner. "There is a growing body of research that says that all of us benefit from exposure to the germy world," he says.

It increases our immune system and makes us more resistant to harmful germs when they do get into the wrong place. "Growing up, there was a saying that 'you've got to eat a peck of dirt.' To me that still holds true. A little germ exposure can be good for you."

So, wear socks and carry hand sanitizer, says Dr. Schaffner, "just don't obsess."