QUESTION
When using a public washroom, is it more sanitary to dry your hands with paper towels or a hot-air blower? And if you don't get them immediately or completely dry, can the continued dampness foster the growth of bacteria?
ANSWER
This is a great question because it assumes that you have done the most important part already, which is washing your hands after using the toilet. Drying them is equally important.
Studies have examined how effective various hand-drying techniques are in removing bacteria after washing, and have shown that warm forced-air dryers are generally as effective as wiping hands with paper towels. In fact, one study from the Mayo Clinic found no statistically significant difference between drying hands with cloth towels on a rotary dispenser, paper towels from a stack by the sink, warm forced air from a mechanical dryer, and letting the hands dry naturally by evaporation.
More recently, however, studies have examined some of these techniques in more detail and offered new and important pointers. The first is to keep your hands still when using the air dryer. Avoid rubbing them together, as rubbing prevents the removal of bacteria. Second, when using paper towels make a conscious effort to dry your palms and fingers – not just the fingertips.
While removing bacteria is the key consideration when drying your hands after washing, there are other things to consider as well. Warm forced air from a dryer can chap your hands, and dry or cracked hands will harbour more bacteria than those that are not chapped. In the winter months especially, it is important to keep the skin of your hands healthy by using soaps or lotions containing moisturizers. Gloves and mitts also play an important role in keeping your hands healthy and smooth.
If you don't dry your hands immediately after washing, or if you don't dry them completely, the continued dampness can foster the growth of bacteria. It can also make your hands stickier and more apt to pick up germs from anything you touch.
If your clean, washed hands touch anything before they're dry, they can pick up new germs from the touched surface, for example the button on the forced-air dryer or the dial of a rotary dispenser. Picking up new germs may compromise the entire hand-washing exercise.
Here's how to avoid this problem: With a rotary dispenser, dial a towel before you wash your hands, then rip it from the dispenser afterward. And what about the button on the forced-air dryer? Well, that's what elbows are for!
Dr. Anne Matlow is the medical director of patient safety and infection prevention at the Hospital for Sick Children in Toronto and associate director of the University of Toronto Centre for Patient Safety.