We all know that using hand dryers instead of paper towels is great for the environment; instead of causing trash cans to overflow, hand dryers produce little waste (and the Dyson ones that siphon off excess water from your hands are seriously fun to use). Unfortunately, though hand dryers are good for the earth, a new study showed that they might not be so beneficial for your health: The dryers in public restrooms actually blast hot air that’s full of gross bacteria right onto your freshly washed hands, and the effect can easily make you (and those around you!) sick.

Your hands can be exposed to an average of 18 to 60 bacterial colonies when placed under a dryer for just 30 seconds. Without a dryer, hands collect less than one colony in two minutes.

For the study published in the journal Applied and Environmental Microbiology, researchers set up shop in three bathroom sites in an academic health center to see how bacteria collected on plates, based on different variables. They discovered—prepare to be totally disgusted!—that your hands can be exposed to an average of 18 to 60 bacterial colonies when placed under a dryer for just 30 seconds. Comparatively, hands that are simply exposed to bathroom air but not under a dryer collect less than one colony in two minutes.

So, how can something that’s so eco-friendly be so bad for you? Well, hand dryers blow the air around them—and in bathrooms, especially public ones, that air is chock-full of bacteria from feces, urine, and bathroom surfaces. “It’s reasonable to expect that the more bathroom air, especially if it’s ‘unfiltered’ air, that’s blown on a surface such as just-washed hands, the more bacteria will be deposited on hands,” study co-author Peter Setlow, PhD and professor of molecular biology and biophysics at the University of Connecticut, told Allure.

According to Dr. Setlow, the bacteria blown onto your hands and body can potentially lead to getting a pathogen in your mouth or eyes, which could make you sick—not to mention, you could also transfer it to someone else. Luckily, there’s a healthy alternative: Skip the dryers and the paper towels and use your pants instead, like your mother never told you. You’ll still do the environment a solid and won’t end up taking a virus-causing bacterial colony home with you.

Here’s how wine can fight cavity-causing bacteria. Also, find out how a smartphone app could soon identify dangerous food bacteria.