There's poo on you: Dry hands correctly after a visit to the restroom

Aug. 26, 2015
I watched someone walk out of the restroom and dry her hands on her lab coat. She may have just defeated the entire purpose of washing her hands.


I watched someone walk out of the restroom and dry her hands on her lab coat. She may have just defeated the entire purpose of washing her hands. One of the most overlooked concepts of hand hygiene is simply drying the hands. Not drying hands properly can be the undoing of good handwashing.

Let's face it; restrooms are a place where cross-contamination occurs. Aerosol plumes form when toilets are flushed. These small atomized particles can be suspended in air and travel very long distances, and can stay suspended for up to an hour.


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Dr. Charles Gerba of the University of Arizona studied the distance this invisible cloud could travel and discovered it can go six to eight feet out and up. The areas of the bathroom not directly adjacent to the toilet can be contaminated along with the toilet and toilet paper.1 As this is suspended in the air, further studies tie this situation into the hand dryers in the restroom.

Shockingly, damp hands can spread up to 1,000 times more bacteria than dry ones. Yet more than one-third of Americans (39%) don't always completely dry their hands after washing them. The act of drying hands cannot be overstated. If you wash carefully and follow up with a paper towel, the friction of the paper towel will help with the process of cleaning. Done properly, this aids in creating an almost germ-free surface, with up to 99% of germs being removed.2 Washable towels that are used repeatedly for drying hands can harbor bacteria and have been shown to be a possible source of cross-contamination. They should not be used in the dental setting.

So what do you dry with?

Air dryers: Bacteria and viruses as well as fecal matter can be suspended in the air. Ian Eames, professor of fluid mechanics at the University College London, says, "Fecal matter and droplets of urine can be found in washroom air. These small particles can stay in the air and be transported around the washroom area. Most hand dryers draw in contaminated air and direct it straight onto your hands."

There is a misconception that rubbing your hands under a blow dryer can help get rid of any remaining bacteria. The opposite is true. Research found that rubbing hands together under the blow dryer's warm air increases the amount of bacteria on the surface of the skin.3

The problem goes much further. Most hand dryers do not filter air; rather, they recycle dirty air. The most effective way of keeping the bacteria count down and eliminating most bacteria is to use a paper towel and thoroughly but gently dry the hands without rubbing them together.

An interesting study from Mark Wilcox, a University of Leeds School of Medicine professor, found that the problem is not just limited to warm-air hand dryers. High-powered jet-air and warm-air hand dryers can spread bacteria in public restrooms. By mimicking hands that had been poorly washed, it was found that air bacterial counts close to jet dryers were:

• 4.5 times higher around warm air dryers, though the jet air dryers also had high counts

• 27 times higher by the air dryers than by the paper towel dispenser

Both jet and warm air hand dryers spread bacteria into the air and onto users and people nearby.

Making this even more complex, bacteria persisted next to the dryers and could be detected in almost half (48%) of the cases for up to 15 minutes after the drying of 15 seconds ended. The issue here is not that bacteria is just staying on the hands, but people can be splattered by other people's bacteria as they use the dryer or the restroom.

The Mayo Clinic Review of 12 studies4 goes further:

• Most people do not use the air dryer for the full 15 seconds, leaving hands moist and making the transfer of fecal matter, bacteria, and anything on door handles, etc., easier.

• Skin irritation increases by using the air dryer because the dryer rapidly strips moisture from the hands.

It is important to dry your hands after you wash them to prevent the spread of bacteria. Air hand dryers can contaminate the area surrounding them. Using paper towels gently has been shown to be the most effective way of removing bacteria and not filling the air with debris, bacteria, and viruses. Drying your hands properly is as important as washing them. RDH


1. http://www.rdhmag.com/articles/print/volume-31/issue-1/columns/world-toilet-day-and-infection-control.html accessed 6.5.2015.
2. Patrick DR, Findon G, Miller TE. Epidemiology and Infection.
3. Snelling AM, Saville T, Stevens D, Beggs CB. (2010) Comparative evaluation of the hygienic efficacy of an ultra-rapid hand dryer vs. conventional warm air hand dryers. Journal of Applied Microbiology.
4. http://www.mayoclinicproceedings.org/article/S0025-6196(12)00393-X/fulltext accessed 6-5-2015.

NOEL BRANDON KELSCH, RDHAP, is a syndicated columnist, writer, speaker, and cartoonist. She serves on the editorial review committee for the Organization for Safety, Asepsis and Prevention newsletter and has received many national awards. Kelsch owns her dental hygiene practice that focuses on access to care for all and helps facilitate the Simi Valley Free Dental Clinic. She has devoted much of her 35 years in dentistry to educating people about the devastating effects of methamphetamines and drug use. She is a past president of the California Dental Hygienists' Association.