Myth No. 3: It doesn’t do any good to use antimicrobial agents in soaps and cleaners; odds are that these agents won’t kill the germs, but they could end up making the germs stronger and your immune system weaker. 

The idea that you can clean yourself sick is called the hygiene hypothesis, and while there is some evidence to suggest that immune system malfunctions, such as allergies, asthma and eczema, may be on the rise because we are not exposed to as many germs as we used to be during childhood, some experts see holes in this logic.

“My informed feeling based on the work that I’ve looked at is that [the rise in some diseases is] not because we’re too clean,” says Scott. “If you take it to its logical conclusion, if being too clean is compromising our health, let’s look at a community in Zimbabwe and look at what’s happening there,” Scott says. “That’s a community that’s definitely not able to be too clean, they’re experiencing a huge onslaught of microbial pathogens all the time, and they’re very, very sick.”

Theories like this one are useful for research but in everyday life, “Certainly, if you’re already immunocompromised,” Scott says, “you cannot be too clean.”

Still, Scott says it is smart to be judicious about using disinfectants. She advocates what she calls a targeted hygiene practice – using antimicrobial chemicals only in areas that are most likely to harbor germs that may pose a threat to health, like the kitchen sink or on frequently touched surfaces like remote controls, keyboards, or faucets.

Scott says you probably don’t need to use cleaners with germicidal ingredients on places like windows and floors, which tend to be relatively free of bacteria and viruses. The only time you might want to disinfect a floor, Scott says, is if you have a little one who is crawling, and there’s a sick person or pet in the house that has vomited or defecated.

Myth No. 4: You are likely to catch a cold from someone who sneezes two feet away from you in an office or a plane.

It’s certainly possible, Scott says, but it’s not likely. Based on her studies of how people come into contact with germs, she says you are more likely get sick after picking up a virus on your hands and then touching your face. “We, all of us, touch our faces so many times a day that we inoculate our eyes, in particular, and then the virus moves down into the nose,” Scott says.

Tear ducts are particularly vulnerable. They don’t have as many defenses against germs as your mouth or nose, Scott says, so you’re most likely to get sick by touching a contaminated surface and then rubbing your eyes.