Yet, another study is conjuring up visions of a swirling cyclone of bacteria and other microbes. For a study recently published in Applied and Environmental Microbiology, a team from the University of Connecticut Health (Luz del Carmen Huesca-Espitia, Gabrielle Joseph, Jaber Aslanzadeh, and Peter Setlow) and QuinnipiacUniversity (Richard Feinn and Thomas S. Murray) brought bacteria culture plates into 36 men's and women's bathrooms in an academic health center and exposed these culture plates to the air blown from the hot air driers for 30 seconds. After this exposure, an average of 18 to 60 colonies of bacteria grew per plate. This included colonies of bacteria that could cause diseases in humans. Compare that to an average of 1 or less colonies per plate when they exposed the culture plate to bathroom air for 2 minutes without the hand dryers running. Installing HEPA (high efficiency particulate air) filters into the dryers did reduce the amount of bacteria by 4-times but did not remove all of the bacteria that could potential cause diseases.

The results of this study don't seem to be just hot air. Other studies have shown similar results. A study published two years ago in the Saudi Journal of Biological Sciences found the following array bacteria from the air flow of fifteen air dryers: Staphylococcus haemolyticus, Micrococcus luteus, Pseudomonas alcaligenes, Bacillus cereus and Brevundimonad diminuta/vesicularis. Also, a study published in the Journal of Hospital Infection coated study subjects' hands with lactobacilli to simulate poorly washed, contaminated hands, and then had the subjects use a jet air dryer, a warm air dryer, or paper towels to dry their hands. When the subjects used a jet dryer 4.5-times more bacteria was spewed into the air than when a warm air dryer was used and 27-times more bacteria was spewed than when paper towels were used.

And here's a CBS 2 Chicago showing how yucky many hand dryers are:

Call me not a fan of hot air hand dryers. If you haven't figured it out, bathrooms aren't the cleanest of environments. Thar be poo in them. And hot air hand dryers really blow. Running such a dryer can be a bit like bringing a leaf blower into a bathroom, sucking in air, bacteria, viruses, and potentially poo and then forcing them out with great speed. Moreover, when a bathroom has no paper towels and just an air dryer, you don't have anything to use to wipe your face or blow your nose (please do not blow your nose with a hot air hand dryer).

While not all microbes being blown around by these dryers are dangerous, the possibility that the dryers are acting as microbe and poo incense machines is a bit disconcerting. Since you spend much of your day rubbing your face, other people's faces, and other things with your paws, good hand hygiene is one of the best ways to prevent catching and spreading infectious diseases. The concern is that hand dryers, especially when they aren't kept clean, may be doing the opposite. And it's not because they are blowing smoke up you know where. Rather, they could be blowing stuff from you know where.

Forbes

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