KPRC 2 Investigates: Here is what we found when we tested the air from bathroom hand dryers

Researchers said hot air hand dryers can blow bacteria like fecal matter all over your hands. KPRC 2 Investigates had to test it to answer the question: To air dry or towel dry. Which is safer?

HOUSTON – No one will argue that washing your hands after you use the restroom is important. It’s how you dry them that’s up for debate. You’ve probably heard or read the reports from researchers at respected universities and major medical schools all over the world. Researchers said hot air hand dryers can blow bacteria like fecal matter all over your hands. KPRC 2 Investigates had to test it to answer the question: To air dry or towel dry. Which is safer?

Testing Hand Dryers: Our Methodology

KPRC 2 Investigates recruited indoor air quality expert Jack Mat to test hand dryers in public bathrooms at random. Mat owns IAQ Environmental.

To test the air blowing out of a bathroom hand dryer in a southwest Houston gas station and another one in a west Houston warehouse store, May held petri dishes under the airflow of the dryers. Any bacteria in the air will stick to the agar in the dishes. It is essentially food for the bacteria. Mat then sent the dishes to a lab to culture the dishes for two weeks. We met up with him for the results when the lab report came back.

The Results

“I knew we were gonna find some bacteria,” Mat told investigative reporter Amy Davis. “It’s healthy bacteria that’s normally in the air.”

While the gas station petri dish contained more bacteria, the lab results show none of the bacteria are concerning. They are all bacteria found in the air and environment that won’t make you sick.

The petri dish with the sample from the warehouse chain bathroom was a different story. The lab found bacillus cereus, a bacteria that causes food poisoning. Imagine washing your hands in the bathroom before you go to the food court and order a hamburger or hot dog.

“If it’s on your hands, there’s a good chance you can put it in your system,” explained Mat.

Bacillus cereus can cause vomiting, diarrhea and abdominal pain. Mat says it’s why, if there are paper towels available, using one to dry your hands should be your first choice.

“If I can’t find a paper towel, then I’ll just shake my hands off,” he said.

Mat says the bacteria that comes out of the hand dryer is being pulled from inside the restroom. If you are in a bathroom that is dirtier with more germs and bacteria, it is reasonable to expect that bacteria is sucked into the dryer intake and pushed out onto your hands. It is why he was surprised he didn’t see e. coli or fecal matter from the lab tests.

Hand Dryer manufacturers weigh in

After our broadcast, representatives with Excel Dryer contacted KPRC 2 citing other studies that conclude “the use of hand dryers and paper towels to dry hands were found to be equal from a health and safety perspective.” You can read that study from University of Arizona researchers here. An Excel Dryer representative also wrote, “It’s also important to note that not all hand dryers are created equal and can’t be combined into a uniform assessment. All of our hand dryers are available with HEPA Filtration, proven to remove 99.999% of all viruses from the airstream.” KPRC 2 did not seek out specific types of hand dryers in this test. We walked into a gas station bathroom and the restroom of a major warehouse chain, just as any consumer would do if they needed to use the restroom.


About the Author:

Passionate consumer advocate, mom of 3, addicted to coffee, hairspray and pastries.