Bumping fists rather than shaking hands could reduce the spread of infectious diseases, researchers have said.
Academics at Aberystwth University in west Wales came to the conclusion following a series of tests on hand hygiene.
Using rubber gloves and a thick layer of the potentially deadly bacteria E.coli, scientists exchanged handshakes, high fives and fist bumps before working out which greeting gesture was the cleanest.
According to the study, high doses of bugs were passed on during a handshake.
However, that was reduced by more than half during a high five and 90% when bumping fists.
Dr Dave Whitworth, senior lecturer at Aberystwyth University, said the hygienic nature of the fist bump was in part due to its speed as well as there being a smaller contact area.
"People rarely think about the health implications of shaking hands. But if the general public could be encouraged to fist bump, there is a genuine potential to reduce the spread of infectious diseases."
Dr Whitworth added the study, published in the August edition of the American Journal of Infection Control, was inspired by increased measures at promoting cleanliness in the workplace through the use of hand-sanitisers and keyboard disinfectants.