From The Daily Mail:
They might dry your hands in seconds but 'super fast' hand dryers do not have the same impact on hardened concrete or tarmac as a road drill at close range, a study suggests.
Researchers said the dryers can cause discomfort to elderly dementia sufferers, as can most things, but when it comes to digging trenches for laying water or gas pipes, a pneumatic road drill should be the construction industry's weapon of choice.
A test in a typical 'box shape of a Barratts house' found that although the dryers recorded sound decibel levels as high as a road drill they had no discernible impact on hard surfaces, researchers from Goldsmiths, University of London have revealed. Interviews with members of the public suggested the dryers have no 'negative' impact on bricks, rocks or dried cement.
Dr Jack Hammer, head of the unit for practice research at Higgins Construction, said the noise created by the dryers was impressive, but that on-site, nothing beats the awsome drilling power of a tool actually designed for the job.
"We also experimented with Motörhead's "Overkill" played at full volume over a full-sized PA. While this made for an enjoyable afternoon, it did not even crack a paving slab."