The Science of Hand Dryers

Do you consciously consider the most sanitary way to wash your hands while washing them? According to the Centers for Disease Control and Prevention (the CDC), the correct process for washing your hands is (1) wet your hands, (2) apply soap, (3) scrub for at least 20 seconds, (4) rinse, and finally (5) dry your hands with a clean towel or air dry them. Air drying your hands is an easy, environmentally-friendly way to dry your hands. However, is there even any point to washing your hands in the first place if you’re just going to air dry them after? To put it simply: no.

Every time you flush the toilet, bacteria as well as fecal matter is shot into the air, reaching heights of 15 feet. This is then sucked into the air dryers and blown onto your hands (Cassella). This type of fecal bacteria can cause diseases (Mayo Clinic).

An experiment was conducted at the University of Connecticut. Petri dishes were placed in bathrooms, one away from the air dryer and one under the air dryer. The one away from the air dryer had approximately one bacterial colony present, while the one exposed to 30 seconds of air dryer air had approximately 18 to 60 bacterial colonies per plate.

If you can’t use hand dryers, what should you use instead? According to the Mayo Clinic, “from a hygiene viewpoint, paper towels are superior to electric air dryers.” When you rub the paper towels against your wet hands, they create friction, which helps in removing germs (Petri).  The Mayo Clinic also concluded that people preferred paper towels over air dryers – 55 percent preferred paper towels in 2009.

What if paper towels are not an option? Which option results in less bacteria – an air dryer or not drying your hands at all, considering the wetness of your hands can increase the survival of bacteria? The Mayo Clinic performed a study on the cleanliness of air dryers comparing the bacteria on your hands before and after air drying, and the air dryers increase the number of bacteria on your hands.

To conclude, avoid air dryers at all costs, unless you enjoy coming out of the hand-washing process more dirty than when you started.


Are Hand Dryers Sanitary? (n.d.). Retrieved from
Cassella, C. (n.d.). Here’s The Gross Truth About Bathroom Hand Dryers. Retrieved from
CDC Features. (2018, October 11). Retrieved from
Perez, C. (2018, February 08). Viral Facebook post has people thinking twice about using hand dryers. Retrieved from
Petri, A. (2012, December 14). The paper towel-hand dryer wars are over. Retrieved from

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