440,000 units of bacteria, toxins and dirt are just a few reasons you shouldn't wear your shoes in the house.
Last week we brought you the horrifying amount of bacteria on your kitchen sponge. This week, it's the stuff on your shoes that has our attention.
An experiment from two University of Arizona professors found that in just a fortnight a brand new pair of shoes managed to attract 440,000 units and nine different species of bacteria to their soles.
"The common occurrence (96%) of coliform and E. coli bacteria on the outside of the shoes indicates frequent contact with fecal material, which most likely originates from floors in public restrooms or contact with animal fecal material outdoors," said Dr. Charles Gerba, a microbiologist and professor at the University of Arizona.
"Our study also indicated that bacteria can be tracked by shoes over a long distance into your home or personal space after the shoes were contaminated with bacteria."
Volunteers were asked to walk on clean tiles wearing the dirty shoes.
Over 90 percent of the time the bacteria transferred directly onto the clean tiles.
Further proof that the practice of removing your shoes is more than just good etiquette: studies found that shoes also tracked inside harmful toxins and dirt.
The same research found that washing your shoes with detergent removes almost 90% of bacteria - so it's not all bad news.
Best get scrubbing those soles.