Go ahead, get dirty

Being too clean may be making members of the developed world more prone to illness, researchers say.

The “hygiene hypothesis,” produced in 1989 by epidemiologist David P. Strachen, asserts that early exposure to microbes allows our immune systems to identify what’s harmful and what isn’t, according to The Washington Post. If early exposure doesn’t take place, the immune system can become overly sensitive and overreact to non-threats like pollen or dander.

A 2012 study of Amish and Swiss children found that those who grew up on a farm—where they were exposed to livestock and associated microbes, and more likely to drink raw milk and have more siblings—had significantly lower rates of asthma, hay fever and eczema.

“You don’t need to use antibacterial soaps or wipes, or clean everything with bleach, or even wash your clothes every day,” said Michael Zasloff, an immunologist at Georgetown University Medical Center.