Germs often spread from hand to mouth so frequent hand-washing can reduce the threat. Or can it? Once your hands are clean, what is the best way to keep them clean as you get them dry?
We've all been in public restrooms where that thought pops into our minds, especially restrooms that offer a choice of paper towels or blowers.
Australian researchers recently put this question to the test. Scientists at Queensland University in Brisbane looked at a dozen independent studies comparing the effectiveness of cloth towels, paper towels and machines that blow hot air.
Perhaps it was no surprise, but the researchers concluded that paper towels are more effective than blowers.
"The provision of paper towels should be considered as a means of improving hand hygiene adherence," the study concluded. The study focused on removing water from the hands. A paper towel, it said, did it better and faster.
The results showed that with just 10 seconds of drying with a single-serve towel, the residual water on the hands was reduced to just four percent and dropped to just one percent with 15 seconds of drying. Air dryers were much slower and required 45 seconds to reduce the residual water to three percent.
The bottom line -- paper towels can generally achieve 90% or more dryness with normal use, the study said.
Why is it so important to dry hands after washing? Because bacteria can remain when hands are wet. The researchers found that paper towels "reduced the numbers of all types of bacteria on the hands." Hot air dryers, not so much.
A few years ago there was an email circulating around the Internet claiming that schools and colleges that employ electric blowers in restrooms have been linked to the spread of the H1N1 flu virus. The site Snopes.com, which specializes in debunking urban legends, says it has been unable to confirm the email's claims that blowers have been removed from public restrooms for that reason.
CDC weighs in
While remaining neutral in the debate over which is best, the U.S. Centers for Disease Control (CDC) does in fact, point out a blower requires more drying time than a paper towel, but also that complete drying can't be accomplished with just one towel.
“Wet hands have been known to transfer pathogens much more readily than dry hands or hands not washed at all,” the agency says. “The residual moisture determines the level of bacterial and viral transfer following hand washing. Careful hand drying is a critical factor for bacterial transfer to skin, food and environmental surfaces.”
When drying hands with a paper towel, the CDC suggests using two towels, drying hands with the towels for 10 seconds each. When using a blower, the CDC recommends keeping air blowing on your hands for 30 to 45 seconds.
“A prolonged drying period is required to achieve complete drying,” the agency says.
The towel vs. blower debate has even pervaded popular culture. In an episode of the popular sitcom “The Big Bang Theory,” Sheldon goes on a rant about the blowers in the university's restrooms.
The Australian study, no doubt, will stoke the heated competition between companies that sell paper towel dispensers and those that sell and install hot air blowers. Think of all the public restrooms in the world and you quickly see what's at stake.
Meanwhile, the details of the study are enough to terrify even the bravest germaphobe. keeping them out of public restrooms forever.
"When a toilet is flushed a fine aerosol mist can be sprayed into the air,” the researchers say. “This mist may contain may types of fecal bacteria that can cause diseases. Air movement can encourage the dispersal and transmission of bacteria and increase the chance of cross-contamination.”