How hand dryers spread bacteria

Those harmless looking hand-dryers in public bathrooms aren't so harmless after all! According to an interesting study published in the Journal of Hospital Infection, modern-day hand dryers in public bathrooms spread 27 times more bacteria than paper towels into the air.

To test this theory, all the members of a research team led by Professor Mark Wilcox of the School of Medicine coated their hands with a harmless type of bacteria called Lactobacillus, which isn't normally found in public bathrooms. This was done to visualise how droplets are dispersed. Subsequent detection of the Lactobacillus in the air proved that it must have come from the hands during drying. The experts collected air samples around the hand dryers and also at distances of one and two metres away.

The study found that as the hand-dryer removes moisture from a user's hands, it throws bacteria into the air and onto people. It was also proved that that both conventional (warm air) and high-velocity (jet air) dryers alike spread bacteria into the air and onto users and those nearby.

The air bacterial count close to jet air dryers was found to be 4.5 times higher than around the warm air dryers and 27 times higher when compared with the air while using paper towels. Next to the dryers, bacteria persisted in the air well beyond the 15 second hand-drying time, with approximately half (48 per cent) of the Lactobacilli collected more than five minutes after drying ended. Lactobacilli were still detected in the air 15 minutes after hand drying.

According to lead researcher Professor Mark Wilcox, "Next time you dry your hands in a public toilet using an electric hand dryer, you may be spreading bacteria without knowing it. You may also be splattered with bugs from other people's hands. These findings are important for understanding the ways in which bacteria spread, with the potential to transmit illness and disease."

As interesting as this study is, it's also facing questions from industry experts on its authenticity. A spokesperson for a dryer company told a leading news daily that this study has been commissioned by the paper towel industry and is flawed. Professor Wilcox acknowledged the fact that the study was funded by the European Tissue Symposium, an association of tissue paper producers. But he concluded by saying that "the group played no part in the results analysis."