One of my passions surrounding “biological awareness” so-to-speak is proper hand-washing behavior (see my BuzzFeed article – http://tinyurl.com/BacterialResistance). The perspective I want to take today, however, is actually the practice of drying hands after washing them. What is the best way to dry your hands post-cleansing? *My perspective of “best” = most sanitary*
Let’s look at some common options:
- Hand dryer
- Paper towels
- Cloth towel
Let’s go ahead and knock out that last option. Cloth towels are infamous for quickly becoming cesspools of germs like Coliform bacteria and Escherichia coli (1). E. coli is an infamous pathogen known for playing a role in cases of food-poisoning. Coliform bacteria are a group of bacteria commonly transferred by fecal contamination. These bacteria alone are not highly pathogenic, but their presence indicates a high incidence of other more dangerous germs that are similarly transmitted.
Poor hand-washing techniques exacerbate the colonization of these microorganisms. When microorganisms colonize, they are growing into communities of germs that are derived from a common ancestor and are increasingly resilient as they grow into larger numbers. If one person does not adequately scrub their hands with soap and remove all dangerous infectious agents while washing, these leftover germs are transferred to the cloth towel. Also, since hand towels will realistically remain moist during the majority of their existence, essentially the perfect environment is created for many bacteria to grow and thrive until the next person comes along to dry their hands. Little does this person know, all progress made moments ago at the sink are erased (and potentially made worse) by re-infecting your hands with the germs harbored by the towel.
Our next option: utilizing hot air and friction (by rubbing your hands together) under an automatic hand dryer. This may seem like the best option because often you do not have to press a button or touch anything else after cleaning your hands. The preferred hand dryer is motion-activated and effectively dries your hands in 45 seconds. UNC Chapel Hill pharmacy student and science enthusiast Tim Angle is convinced that the warm air from these dryers is generated from a place swarming with bacteria. “Air dryers distribute bacteria due to their moist, warm environment that is prime for growing bacteria,” Angle explains. However, back in 2000, scientists showed that the air emitted from hand dryers is in fact just as sanitary as paper towels (2). In addition, in 2012, a group of researchers found that the air leaving a hand dryer actually had fewer microorganisms than the air entering it (3).
Nevertheless, Angle is still correct about the capability of warm air hand dryers to spread bacteria. This seemingly flawless method of using air to dry just-washed hands is still, in some ways, faulty. According to an article by three scientists comparing the hand-drying efficacy of various methods, warm air dryers and jet air dryers are more likely than drying hands with paper towels to spread potentially infectious droplets to the environment (4).
Dr. Christy Esmahan, a molecular biologist, brings up another flaw of warm air hand dryers. “It takes so long that people tend to leave with their hands still moist — a magnet for fresh germs.” Just like a wet cloth towel provides a fruitful breeding ground for germs, still-wet hands provide the same environment, especially when people leaving a restroom are highly likely to touch door handles and cell phones within seconds.
Considering my strictly sanitation focus, paper towels could very well be the best method for hand drying. One-time use greatly decreases risk of contamination in comparison to cloth towels. In addition, using paper towels includes the same benefit of frictional removal of bacteria as rubbing hands under a warm air dryer, while eliminating the high incidence of spreading potentially contaminated droplets to the environment.
Indeed, in a study of 47 random participants, a large majority preferred paper towels to warm air hand dryers (Image 1). However, the evidence for the sanitation of paper towels may not be enough to convince the large number of environmentally-concerned citizens to abandon warm air hand dryers and cloth towels. 63% of people preferring hand-drying methods other than paper towels mentioned reduction of waste as the main motivation for their choice. In addition, although the large majority of the surveyed participants did choose paper towels as their hand-drying method of choice, only 25% of those participants mentioned cleanliness and sanitation as their reasoning. 25% rationalized their choice with speed and efficiency.
Therefore, the concluding question seems to be not only “Which method is the most sanitary?” but also “How should the most appropriate method be communicated?” and, thinking holistically, “Should we be more concerned about sanitation or waste reduction?” Those who are biologically biased will likely continue to clash with the environmentally-minded. However, potential future projects that could bring the two fields together could revolve around biodegradable paper towels, for example. Ultimately, the question you should be asking yourself after reading this article is this:
What will it take to change YOUR daily hand-drying habits?
- Gerba, Charles P., Tamimi, Akrum H., Maxwell, Sherri, Sifuentes, Laura Y., Hoffman, Douglas R., Koenig, David W. 2014. Bacterial Occurrence in Kitchen Hand Towels. Food Protection Trends. 34(5): 312-317.
- Best, E.L., Parnell, P, Wilcox, M.H. December 2014. Microbiological comparison of hand-drying methods: the potential for contamination of the environment, user, and bystander. Journal of Hospital Infection. 88(4): 199-206.
- Huang, C., Ma, Wenjun, Stack, Susan. 2012. The Hygienic Efficacy of Different Hand-Drying Methods: A Review of the Evidence. Mayo Clinic Proceedings. 87(8): 791-798.
- Tayler, J.H., Brown, K.L., Toivenen, J, Holah J.T. December 2000. A microbiological evaluation of warm air hand driers with respect to hand hygiene and the washroom environment. Journal of Applied Microbiology. 89(6): 910-919.