Field of Science

Hand dryers.. a pain?

Most of you have probably noticed an increase in 'paperless technology' and automated systems, particularly in public toilets. 

In some places you don't even touch the flusher, and you then end up stand there frustratingly waving your hands to get the automated taps to work (and you probaly end up getting water splashed all over yourself!). Then you arrive at the hand dryer, and if your lucky enough to use a Dyson one then you practically feel like your hands are in the middle of a wind tunnel.

Yes paperless technology is a small step in saving the planet, and none of us want to feel responsible for killing the polar bears, but is it as effective as the paper alternative? Especially at reducing bacteria?

Dyson Airblade (www.dysonairblade.co.uk)

Published in the September 7th edition of the Journal of Applied Microbiology (via www.sfam.org.uk) is an article that compares how good these 'ultra rapid' hand dryers are and compares them to other methods.

Everyone carries large numbers of bacteria on their hands due to daily activities with most being completely harmless, known as commensals, which just essentially 'chill out' on our skin. However if we do activities such as; touching raw meat, going to the toilet and digging in the dirt, then these increase the chance of us having harmful bacteria on our hands, such as some MRSA, E. coli and Salmonella species. Hand washing with soap and water decreases the number, but does not neccessarily elliminate the bacteria. If appropriate hand drying does not occur then these bacteria are easily transferred to other surfaces.

So the hand dryer vs. paper towels. The research was conducted at the University of Bradford and they looked at a variety of hand drying techniques and their effect on the number of bacteria on the participants' hands. 
The methods used were rapid velocity dryers (Dyson), conventional hand dryers and paper towels. The researchers measured the number of bacteria on the hands of volunteers before and after different drying techniques so that the reduction of bacteria could be calculated. 
SLS Paper towels (http://www.scientificlabs.co.uk/image/display/CLE2384)

The participants dried their hands with the above methods, with and without rubbing their hands and Dr. Snelling and her team found that rubbing your hands together whilst using traditional dryers was worse and did not reduce the bacteria after hand washing compared to 'non-rubbing'! 
This is beacuse when rubbing the bacteria are spread over your hands, instead of removing them. If hands still contain moisture then they are more likely to be transferred to other surfaces. Also, the rapid velocity dryers were more effective after 10s compared to conventional dryers (30s) therefore if all moisture is removed then you are less likely to transfer bacteria to other surfaces. 

However, when hands are rubbed with a  paer towel this removes bacteria from the skin and gave the best results overall, "the most hygienic method of drying is using paper towels." - Dr. Snelling

So, those Dyson hurrican machines are actually better than the old hand dryers then? Well they definetly feel like they're getting rid of all your moisture! So using one of them, without rubbing is the best automated drying technique, and no doubt the quickest in 10s. 
I won't, however, rush into installing one of those 'beasty' machines in my house tho(even if they are now available in 'white').... I'll stick with my pink towel ;-)


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