That Viral Hand Dryer Petri Dish Isn't as Scary as it Looks

Not all bacteria make you sick, even when they're from the bathroom.

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Do you get grossed out by public restrooms? If you’ve seen Nichole Ward’s viral hand dryer experiment online, you may be even more disgusted than than usual, but a closer look suggests your fears are mostly unwarranted.

In a Facebook post on January 30, Ward shared a photograph of a nasty-looking petri dish that looks like the food your roommate left in the fridge a couple months ago. But the organisms growing on it aren’t from a bathroom-tainted smartphone, a stack of nasty cash, or a spit-sprayed birthday cake: They’re from the air under an enclosed public bathroom hand dryer. After two days, a whole mess of bacteria and fungi erupted on the dish, and since then, the plate’s photo has been shared over 500,000 times and has accumulated more than 143,000 likes.

“I stuck the open plate in an enclosed hand dryer of a public bathroom for a total of 3 minutes. Yes 3 only,” Ward wrote in her post. “DO NOT EVER dry your hands in those things again.”

Here’s what it looks like:

Pretty nasty, right?

“This is the several strains of possible pathogenic fungi and bacteria that you’re swirling around your hands, and you think you’re walking out with clean hands,” Ward writes. Without exactly saying it, she seems to be suggesting that a blow dryer is circulating fecal particles onto your hands when you use it.

There’s no question that her image is pretty shocking, but what she shows is not nearly as scary as what she suggests.

Bacteria and Fungi Are Literally Everywhere

Your body is covered with bacteria, yeasts, fungi, and even some viruses. That doesn’t mean there’s anything wrong with you, though. Your microbiome protects your skin, aids in digestion, and helps keep you from getting a yeast infection, among other things. The mere fact that there are bacteria in a restroom should surprise precisely nobody because where there are people, there are bacteria.

That’s not to say, of course, that you shouldn’t wash your hands. The human body is more accustomed to some bacteria than others, and even then it can only tolerate certain amounts of different bacteria. Washing your hands aids in the body’s ability to self-regulate its regular bacterial film and avoid the strains it would rather not deal with.

Dirty Hand
If you're worried about getting bacteria on your hands, well, it's too late. They've always been there.

Not All Bacteria Make You Sick

In the post, Ward says the organisms she grew in the dish include “several strains of possible pathogenic fungi and bacteria.” She doesn’t explain whether she identified them, so we can’t say whether her claim is valid. Sure, it’s possible that they are pathogenic, but it is just as likely they are not. We simply can’t say. Though it’s fair to argue that if hand dryers regularly spewed out pathogenic bacteria in quantities that could make you sick, you’d probably get sick every time you went to a restroom that had electric dryers installed.

Suffice it to say, there are tons of bacteria and fungi in addition to the ones that live on your body that won’t make you sick. Know what gives aged salami its taste? Fungi. Know how bakers make sourdough bread? They catch yeast floating in the air. These microbes are perfectly safe to consume.

Growing Bacteria in a Dish Doesn’t Prove Much

In the comments of her post, Ward says she used a petri dish that contains Sabouraud Dextrose Agar, a common laboratory growth medium that encourages whatever microbes are in the dish to grow and multiply. There is no such growth medium on bathroom floors, walls, hand dryers, or sinks, so even if the microorganisms are there, they aren’t growing like they grew in the dish. In fact, each of the colonies on the petri dish (looks like five total) could have come from just one spore or bacterium. For three minutes of blowing all that bathroom air around, five microorganisms is actually a pretty small number.

Ward doesn’t indicate her level of scientific training, but she seems to know at least some microbiology basics. Inverse has reached out to her for comment and will update the story when we hear from her.

At the end of the post, Ward says, “this post is simply for awareness, not to instill fear.” But without proper context, a post like this does exactly that. Without details or context, how can you spread awareness?

Her “experiment” brings to mind a viral science project that suggests that wifi routers stunt the growth of plants. As in Ward’s experiment, the design of that project was questionable at best, and the results are so weak that the only way to make it convincing is to let people draw their own conclusions. In this case, people’s conclusions — as evidenced in the comments — are quite fearful indeed.