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 / Updated  / Source: TODAY
By Julie Pennell

There are two kinds of people in this world: those who wear shoes in the house and those who don’t. And while each side has its pros and cons, there’s one glaring reason why you should slip off your shoes when you walk inside. We’ll just be blunt here — that reason is poop.

Dr. Charles Gerba, professor of microbiology and environmental sciences at the University of Arizona, studied the bacteria on the bottom of shoes and found that they can track all kinds of gross stuff inside homes.

“If you wear shoes for more than a month, 93 percent will have fecal bacteria on the bottom of them,” he told TODAY Home about his findings. Gerba credited things like pet waste on the ground outside and splashes from the toilet on public restroom floors for this contamination.

“We found E. coli, too,” he added. The bacteria is usually harmless but some strains can make you sick, causing diarrhea or urinary tract infections, respiratory illness and pneumonia, and other illnesses, according to the CDC.

“Shoes make microorganisms fairly mobile, and you’re tracking that all around (the house),” Gerba said, adding that the cracks on the bottoms of shoes make it more conducive for bacteria to hang around.

If you have small kids who are crawling around and sticking things into their mouths, this could definitely be an issue, he noted.

Does this make you want to leave them outside?Getty Images stock

“Also, if you’re immunocompromised or have allergy issues, it’s a good idea to take your shoes off,” he said. That’s because shoes also pick up mold and allergens like pollen.

And if you have carpet, it’s probably even dirtier. Organisms can survive longer in carpet, plus bacteria and mold can build up over time. “A hard floor is easier to clean and disinfect,” Gerba said.

Speaking of disinfecting, Gerba and his research team found that when the shoes were washed per manufacturer’s instructions (in this case, in the washing machine), there was a 99 percent reduction of bacteria on the outside of the shoe.

But let’s face it: Who’s going to wash their shoes just to be able to walk in the house with them? If you’re insistent on wearing shoes indoors (for comfort, convenience or whatever the reason may be), you could always try an antimicrobial doormat.

Dr. Doormat is one brand that makes them, and claims that wiping your shoes at least twice on the mat can trap and remove up to 90 percent of the debris from the bottom of your shoes.

Here are a few more antimicrobial doormats we love:

Notrax Aqua Trap Entrance Mat, $63, Amazon

Amazon Best Seller: 71 reviews, 4.7 star rating

TODAY editors, writers and experts take care to recommend items we really like and hope you’ll enjoy! Just so you know, TODAY does have affiliate relationships. So, while every product is independently selected, if you buy something through our links, we may get a small share of the revenue.

GrassWorx Doormat, $25, Amazon

419 reviews, 4.5 star rating

Clean Machine Filigree Door Mat, $22, Home Depot

4 reviews, 5 star rating

But the easiest and likely the most reliable way to keep floors clean is to take shoes off when entering the house (and maybe put on some cozy slippers). And after a hard day’s work, isn’t that all you want to do anyway?

This story was originally published May 30, 2018.