If you have a nasty cold one of the most effective ways to spread it is to wet your hands and then plunge them into a 400 mph blast of air capable of carrying viruses three metres across the room.

That, at least, is the conclusion of scientists who have found that using a jet-air dryer, such as a Dyson Airblade, spreads 60 times more bugs than an old-fashioned warm-air model and 1,300 times more than paper towels.

With about 40 per cent of hospital infections thought to be caused by poor hand-washing, the stakes are high in the war of information between hand-towel manufacturers and electric hand-dryer firms.

Medical researchers at the University of Westminster tested the different techniques with a virus called MS2,