A New York Times story tackles an interesting if low-grade health question: Should you take your shoes off before going inside? After talking to several scientists about the matter, the article by Christopher Mele comes to a general conclusion: If it's just a matter of health—that is, worry about tracking in germs—you can probably leave them on. Your shoes definitely do track in all kinds of bacteria from dog poop and the like, but it's all about context. Harmful bacteria is present just about everywhere (the money in your pocket, kitchen sponges, on your fingers after using an ATM or gas station pump, etc.), and the threat presented by your shoes isn't all that great in the grand scheme. "For most healthy adults, this level of contamination is more of a gross reaction than a health threat," says biomedical sciences prof Lisa Cuchara of Quinnipiac University.
Some exceptions: If a baby is crawling around or if someone in the house has allergies or a compromised immune system from a disease, it's wise to take the shoes off. (Etiquette is a whole different story, notes Mele. In some cultures, it's disrespectful to leave shoes on, so take care to abide by the host's wishes.) The issue of dirty shoes came to the public's attention in a big way about a decade ago thanks to a study by University of Arizona microbiologist Charles Gerba. "It seems like we step in a lot more poop than I thought," he said back then, summarizing one of the takeaways, per USA Today. But on the subject of dogs, one of the scientists Mele interviews notes that if people are worried about what they're tracking in, just think about what dogs bring in—"and we don't wash the dog's paws every time he comes in the house." (Read more germs stories.)