Hand Dryers Cover Your Hands with Germs

It is difficult to find a person who likes visiting public bathrooms. Not only do they fall short of being squeaky-clean – they also make you stand in line! Actually, there is one more danger that you are probably not aware of: hand dryers contaminate your hands with bacteria. Perhaps, next time you go to a public bathroom you will prefer to let your hands dry on their own.

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When we are in a public bathroom, most of us do our best not to touch any surfaces: the germs inhabiting them scare quite a lot of people. We masterfully evade all droplets of water when someone splashes while reaching for soap, try not to touch buttons that much, and find the idea of sitting on a public toilet disgusting. Having used a hand dryer, we leave the bathroom assured that no germs have got to our hands – you didn’t touch anything after washing your hands, did you? Yet it appears that it’s not that easy.


A team of scientists from University of Connecticut Health and their colleagues from medical centers screened three hand dryers in bathrooms in an academic research center. They used special plates, which they exposed to the hot air from hand dryers for 30 seconds. Having looked at what got to the place surface, they detected a large number of bacteria colonies, which varied from 18 to 60. Surprised by the finding, they started looking for the source of bacteria.

The dryer nozzles appeared to be clean: there were almost no germs there. It indicated that it was the air in the bathroom that was the culprit. The researchers took another set of plates and exposed them to the air in the bathroom for two minutes. It resulted in less than 1 colony on average appearing on them. Then the scientists hypothesized that moving the air in the bathroom could do the trick: they exposed more plates to the bathroom air, which was being moved by a fan. After 20 minutes of exposure, the plates had 12-15 colonies on average on them. Another interesting finding is that hand dryers seem to contribute to germ spreading even on a building scale: the scientists looked for special spores produced in one of the buildings in a laboratory, and found that they – the spores – traveled to different areas, where other hand dryers were located and analyzed.

A safer alternative

When hand dryers turned out to contribute to pathogen spreading, the team started looking for a solution that would help reduce the amount of germs the equipment covers the user’s hands with. They installed HEPA filters, which lead to significant bacteria exposition reduction: there were 4 times fewer colonies. However, harmful bacteria were not eliminated completely and were still detected on plates exposed to bathroom air and hot air from hand dryers.

How do bacteria get into the air?

When you flush the toilet, tiny droplets of water get into the air. These droplets are contaminated with microorganisms from feces, and it is this air that hand dryers use.

A lot of questions remain unanswered, including what bacteria are more likely to be found in such hot air, and whether hand dryers serve as containers for bacteria, or they just move a lot of air, thus making bacteria get to your hands faster.

Next time you go to a public toilet, let your hands dry on their own: it’s not that long, and there will be fewer germs on your hands. Using paper towels is another option, but it would mean more paper waste (that’s not an eco-friendly approach!). Besides, it may turn out that such towels are contaminated with bacteria too, since they are exposed to bathroom air.

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