Part two of this three-part article examines the role of heat in the hand drying process.

Although heated air may speed up the drying process, thereby promoting compliance, it won’t kill germs, according to research.

“Warm air does not kill bacteria,” says Jason Jones, vice president of sales for Cavalier Inc., Norfolk, Virginia. “To aid in the hand hygiene process, the air would have to be so hot that we wouldn’t be able to stand it.”

Not only is the temperature of the air emitted by heated air dryers too low, but also the time of exposure is too short to kill most bacteria or other microbes, says Keith Redway, emeritus fellow in the department of biomedical sciences, Faculty of Science and Technology, University of Westminster, London. Over the years, Redway has conducted several studies comparing different hand-drying methods.

“In theory, a bacterium can survive 1,000 degrees if the exposure time is short enough,” he says. “So you have to take into account not only the temperature but the time — and that’s true even if you’re sterilizing something in the hospital.”

Distributors and researchers alike agree that the air is heated mainly to provide a pleasant hand-drying experience for the end user.

“If the air was hot enough to start killing bacteria it would injure people’s hands, so it’s a comfort consideration rather than a microbial inactivation,” says Schaffner. “We see the same thing with respect to water temperature. You can wash your hands well in cold water, but everyone likes warm water.”

Although warm air improves a user’s hand-drying experience, some experts say that dryers with a heating element are less energy efficient than their non-heated counterparts and may require additional maintenance.
 
“Without heat, you don’t have to worry about maintenance issues with the heating element, so there are no replacement costs or labor costs involved,” says Mark Dowling, an Auburn, Massachusetts-based senior facility sales rep for SupplyWorks.

On the other hand, Hicks points out that the energy costs associated with heating the air could be offset by the length of time the dryer is running. Since non-heated, ambient air may take longer to dry a person’s hands than heated air, the non-heated dryer may use more electricity, because it has to run for a longer period of time.