Jul 5, 2013
There are different ways of drying your hands in public places: paper towels, continuous-loop towels and warm-air dryers.
Washing the hands, and then using paper towels or continuous-loop cotton towels reduced the bacterial count by about 45 to 60 per cent, but washing, and then using a warm-air dryer actually increased the bacterial count by an average of 255 per cent.
The bacteria are already inside the warm-air dryers, due to the warm moist environment. Every warm-air dryer they tested had high bacterial counts on the air inlet and 97 per cent had them on the outlet nozzle surfaces as well. In most cases it doesn't matter, because our immune systems are resilient enough to keep the numbers of these bacteria low and the majority of these bugs are fairly harmless.
With a towel (paper or cloth) you can apply some decent mechanical friction to your hands. This is an important part of the hand-cleaning process. A towel soaks up the water, and the bacteria end up in the bin. You can dry 90 per cent of the surface area of your hand within 10 seconds with a towel. A warm-air dryer cannot dry your hands within 10 seconds. On average, it takes 50 seconds to dry 90 per cent of your hands.
Jet-air dryers have come on the market in the last few years. They blast air at enormous speed. If you can apply some mechanical friction, and rub your hands together, you can dry 90 per cent of your hands within 10 seconds. If the jet-air dryer has a good intake filter, it will stop the bacteria that are already floating in the bathroom air from getting sucked in and blown around. Warm-air dryers were not installed to improve hygiene, but to cut costs.