What's your cleanliness IQ?

muddy child showing dirty hands
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Germs are everywhere, from your hands to your sheets. Microbes live in your house, in your workspace and on your body, and while some are good, not all of them are — and too many of them in one place is just gross. How smart are you about germs? Take our quiz and find out.

Question 1 of 15

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How often should you wash your sheets?

There's no hard and fast rule on this one, but the every-other-week rule is a popular one — that is, unless you sleep with kids or dogs or you sweat a lot. Then you might want to think about washing your sheets once a week.

Question 2 of 15

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public restroom stalls
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Which is the germiest stall in a public restroom?

University of Arizona professor Charles P. Gerba — affectionately known as "Dr. Germ" — says people tend to use the middle stalls in restrooms so that's where all the germs are. Your safest bet is to choose an end, specifically the one farthest away as you walk into the restroom.

Question 3 of 15

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fist bump
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A fist bump spreads about the same number of germs as a handshake.

Once just a twist on a high-five, the fist bump is now used by world leaders as well as athletes. New research from Aberystwyth University in Wales found that the bump spreads one-20th the amount of bacteria that a traditional handshake does.

Question 4 of 15

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woman pushing shopping cart through grocery store
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Where are you likely to pick up germs in a grocery store?

Keep this in mind on your next shopping trip. Researchers at the University of Arizona swabbed shopping cart handles and found the handles had higher counts of fecal bacteria than public restrooms. Food samples can be home to all kinds of bacteria, depending on how long they've been sitting out, how they were prepared, and who else has sampled them. And reusable bags can be a breeding ground for bacteria and E. coli, so wash them regularly.

Question 5 of 15

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woman washing hair
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How often should you wash your hair?

There's no reason to lather up your locks every day. Most people can get by with washing their hair two or three times a week. The longer, thicker or curlier your hair is, the longer you can go between shampoos.

Question 6 of 15

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a port-a-potty, an ATM and elevator buttons
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Which typically has the fewest germs?

Believe it or not, public restrooms and portable bathrooms have fewer bacteria and germs because they're typically cleaned on a regular basis. In contrast, few businesses sanitize their ATM keypads or elevator buttons.

Question 7 of 15

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woman squirting hand sanitizer on her hands
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Using hand sanitizer is better than soap.

The CDC says washing hands with soap and water is the best way to get rid of germs in almost every situation. Some sanitizers don't kill all types of microbes, and they don't work as well if your hands are greasy or dirty.

Question 8 of 15

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cute house in the grass
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Where are germs most likely to thrive in your house?

Most people know that bathrooms are filled with bacteria and germs, so they clean them often with disinfectants. But kitchens also offer a great environment for germs to grow. To cut down on kitchen bacteria, wash and disinfect cutting boards, surfaces and utensils after preparing meat.

Question 9 of 15

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colorful towels hanging on a clothesline
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How often should you wash your towels?

The American Cleaning Institute suggests washing towels every three to four days — more often if you play sports. (You probably need to run a load of laundry, don't you?)

Question 10 of 15

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someone holding a cellphone in front of a toilet
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Which has more germs?

Believe it or not, your cellphone carries 10 times more bacteria than most toilet seats. That's partly because we know bathrooms are germy so we clean them often. But when it comes to cellphones, we're lucky if we wipe them occasionally with our sleeves. To keep your device cleaner, don't share it and wipe it regularly with a gentle antibacterial wipe.

Question 11 of 15

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very messy desk
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Which usually has more bacteria?

Women's desks typically look neater than men's, but they often have accumulated more stuff. Things like lotions and cosmetics and knickknacks are prime incubators for germs. Women are also more likely than men to have food in their desks, and food provides a great place for bacteria to thrive.

Question 12 of 15

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really dirty kitchen sponge
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Which is the least effective way to sanitize a kitchen sponge?

The USDA soaked sponges in a solution of ground beef juice for 48 hours to get microbes to grow. Then they drenched the sponges in bleach, ran them through the dishwasher, and put them in the microwave.  The dishwasher and microwave killed 99.99 percent of bacteria, but bleach only killed between 37 and 87 percent of germs.

Question 13 of 15

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toddler washing hands
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How long should you wash your hands?

That's probably longer than you wash them now. The CDC says you should be able to sing the "Happy Birthday" song twice while you're washing. That includes wetting them, lathering up with soap, rinsing and drying.

Question 14 of 15

Score: 0

daVinci's Vitruvian man drawing
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What's the germiest part of your body?

According to microbiologist Jason "the Germ Guy" Tetro, your hands harbor the most microbes because you walk around touching things all day. According to a study by researchers at the University of Colorado Boulder, the average person's hands carry at least 3,000 different strains of bacteria.

Question 15 of 15

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purse and public restroom sign
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Which is probably full of more germs?

Think about it. Women put their handbags down on floors everywhere, including public restrooms where all kinds of, um, fecal matter resides. And unlike restrooms, which are cleaned and sanitized regularly, purses rarely even get wiped down, so germs just keep on collecting.

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