An average adult can touch as many as 30 objects within a minute, including germ-harboring, high-traffic surfaces such as light switches, doorknobs, phone receivers, and remote controls. But what has the most germs on it?

Avoid touching these surfaces in public places to stay healthy. I wouldn’t consider myself a germaphobe, but I would kind of like to be. At home, you do all that you can to keep the germs at bay. But what happens when you step out the door to go to dinner, do some grocery shopping, or visit the doctor's office? Know where germs are most likely to lurk, as you'll find out here.

Restaurant menus
Have you ever seen anyone wash off a menu? Probably not. A recent study in the Journal of Medical Virology reported that cold and flu viruses can survive for 18 hours on hard surfaces. If it's a popular restaurant, hundreds of people could be handling the menus--and passing their germs on to you. Never let a menu touch your plate or silverware, and wash your hands after you place your order.

Lemon wedges
According to a 2007 study in the Journal of Environmental Health, nearly 70% of the lemon wedges perched on the rims of restaurant glasses contain disease-causing microbes. When the researchers ordered drinks at 21 different restaurants, they found 25 different microorganisms lingering on the 76 lemons that they secured, including E. coli and other fecal bacteria. Tell your server that you'd prefer your beverage sans fruit. Why risk it?

Condiment dispensers
It's the rare eatery that regularly bleaches its condiment containers. And the reality is that many people don't wash their hands before eating, says Kelly Reynolds, PhD. So while you may be diligent, the guy who poured the ketchup before you may not have been, which means his germs are now on your fries. Squirt hand sanitizer on the outside of the condiment bottle or use a disinfectant wipe before you grab it. Holding the bottle with a napkin won't help; napkins are porous, so microorganisms can pass right through, Reynolds says.

Restroom door handles
Don't think you can escape the restroom without touching the door handle? Palm a spare paper towel after you wash up and use it to grasp the handle. Yes, other patrons may think you're a germ-phobe--but you'll never see them again, and you're the one who won't get sick.

Soap dispensers
About 25% of public restroom dispensers are contaminated with fecal bacteria. Soap that harbors bacteria may seem ironic, but that's exactly what a recent study found. "Most of these containers are never cleaned, so bacteria grow as the soap scum builds up," says Charles Gerba, PhD. "And the bottoms are touched by dirty hands, so there's a continuous culture feeding millions of bacteria." Be sure to scrub hands thoroughly with plenty of hot water for 15 to 20 seconds--and if you happen to have an alcohol-based hand sanitizer, use that, too.

Grocery carts
The handles of almost two-thirds of the shopping carts tested in a 2007 study at the University of Arizona were contaminated with fecal bacteria. In fact, the bacterial counts of the carts exceeded those of the average public restroom. Swab the handle with a disinfectant wipe before grabbing hold (stores are starting to provide them, so look around for a dispenser). And while you're wheeling around the supermarket, skip the free food samples, which are nothing more than communal hand-to-germ-to-mouth zones.

Airplane bathrooms
When Gerba tested for microbes in the bathrooms of commercial jets, he found surfaces from faucets to doorknobs to be contaminated with E. coli. It's not surprising, then, that you're 100 times more likely to catch a cold when you're airborne, according to a recent study in the Journal of Environmental Health Research. To protect yourself, try taking green tea supplements. In a 2007 study from the University of Florida, people who took a 450-milligram green tea supplement twice a day for 3 months had one-third fewer days of cold symptoms. The supplement brand used in the study was Immune Guard ($30 for 60 pills; immune-guard.us).

Doctor's office
A doctor's office is not the place to be if you're trying to avoid germs. These tips can help limit your exposure.

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