For
years, many experts thought that using hand air dryers found in public
toilets was more sanitary than using paper towels. But they actually
spread germs, according to new research from the U.K.'s University of
Leeds.
The
researchers found that germ counts around high-powered "jet-air" and
ordinary warm-air hand dryers were 27 times higher in comparison with
the air around paper towel dispensers.
Air hand dryers scatter germs much like
an aerosol can disperses its contents when sprayed, and the study found
that both jet and warm air hand dryers spread bacteria into the air and
onto users and those nearby.
To mimic hands that have been poorly washed, the researchers contaminated hands with a harmless type of bacteria called Lactobacillus, which is not normally found in public bathrooms.
Any Lactobacillus
detected 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 meters away.
Air
bacterial counts close to jet air dryers were found to be 4.5 times
higher than around warm air dryers and 27 times higher compared with the
air when using paper towels.
Bacteria persisted in the air next to the dryers well beyond the 15 second hand-drying time, with approximately half (48 percent) of the Lactobacilli collected more than five minutes after drying ended. Lactobacilli were still detected in the air 15 minutes after hand drying.
Bacteria persisted in the air next to the dryers well beyond the 15 second hand-drying time, with approximately half (48 percent) of the Lactobacilli collected more than five minutes after drying ended. Lactobacilli were still detected in the air 15 minutes after hand drying.
Team
leader Professor Mark Wilcox said: "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."
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