Handwashing for nerds: Are those Dysan jet dryers better than paper towel?

Amy, Sorenne and I spent a long last weekend in San Francisco, where Amy conferenced, I had some meetings, but mainly just hung out with the kid (three pirates and a little girl, right).

The washrooms at the San Francisco airport featured the Dysan airblade, billed as the “fastest, most hygienic hand dryer.” Says so right on the machine. And it’s certified by NSF as “tested, certified, hygienic.” Says so right on the machine.

My bowels are in a state of flux when traveling so I had several opportunities to try out the newfangled machinery, that sounds like an airplane is taking off below your fingertips.

We have maintained, based on our reading of the available literature, that proper handwashing, entails:

• wet hands with water;
• use enough soap to build a good lather;
• scrub hands vigorously, creating friction and reaching all areas of the fingers and hands for at least 10 seconds to loosen pathogens on the fingers and hands;
• rinse hands with thorough amounts of water while continuing to rub hands; and,
• dry hands with paper towel.

Water temperature is not a critical factor — water hot enough to kill dangerous bacteria and viruses would scald hands — so use whatever is comfortable.

The friction from rubbing hands with paper towels helps remove additional bacteria and viruses.

I did a cursory search to find some data on the Dysan thingy, and found a study comparing paper towel, regular blow dryers, and a Dysan-type jet dryer that was published in 2008.

Those authors state:

“The jet air dryer showed that there were significant differences (although not as great as for the fingerpads) between the towels and both types of dryer. Again, the superior performance of the towels in reducing bacterial numbers was confirmed. As for the fingerpads, the jet air dryer performed better than the warm air dryer in not increasing mean bacterial count on the palms as much but this difference was not significant.

“Therefore, the manufacturer’s claim that the tested JAD is the “most hygienic hand dryer” is confirmed, especially for fingerpads and assuming that the term “hand dryer” refers to electric devices only because its performance in terms of the numbers of all types of bacteria remaining on the hands of users compared to paper towels was significantly worse. …

“It is well known to microbiologists that air movements encourage the dispersal and transmission of microorganisms and increase the chances of the contamination of materials or persons in any situation. This makes paper towels, where little air movement is generated, the most hygienic option tested in this respect followed by the warm air dryer and, lastly, the jet air dryer.”

The friction from rubbing with paper towel is particularly effective at reducing microbial populations; yet many of these public bathrooms have signs proclaiming that electric dryers of whatever kind are better, and save the trees. Oh, and I should hear from someone at Dysan or NSF – public claims need to be backed with public data.

Maybe I’ll just stay at home.

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About Douglas Powell

A former professor of food safety and the publisher of barfblog.com, Powell is passionate about food, has five daughters, and is an OK goaltender in pickup hockey. Download Doug’s CV here. Dr. Douglas Powell editor, barfblog.com retired professor, food safety 3/289 Annerley Rd Annerley, Queensland 4103 dpowell29@gmail.com 61478222221 I am based in Brisbane, Australia, 15 hours ahead of Eastern Standard Time