These days, one of the fastest ways of spreading disease is on board commercial airplanes.

People worry not only about catching a cold from the person sneezing in the middle seat next to them, but also about deadly viruses like Ebola. So cleaning airplanes after each flight is serious business. But if you think the government regulates how airlines should clean or inspects how people do it, think again.

Medical studies have shown that air travelers face higher rates of infection. One study pegged the increased risk of catching a cold at 20%. Much of the danger comes from the people within two rows around you. But viruses and bacteria can live for hours on some surfaces like tray tables and seat-back pockets.

It’s also difficult to know what germs are lurking in an airline’s pillows and blankets, which sometimes don’t get sent to the laundry until the end of a day’s flights. There’s little-to-no government inspection of cleaning requirements in the U.S. and other parts of the world. Here’s the typical procedure. For domestic flights within the U.S., planes get a once-over straightening up between flights and usually a more thorough cleaning overnight.

Between international flights, an aircraft gets a better cleaning. And once every month or two, planes get scrubbed from nose to tail when they undergo major maintenance work.

What can you do to protect yourself? Use a lot of hand sanitizer. And if you’re really concerned, carry some wipes to wipe down your tray table, seat back, and armrest. And turn up those air vents in the ceiling panel. The air that comes out of the vents is heavily filtered and much better for you. Improving circulation, even on cold trips, will help you stay healthy.