Grim slow-motion video reveals germs can be propelled 25 FEET when you sneeze
While the largest droplets land one to two metres away, smaller ones are jettisoned up to eight metres and can carry nasty germs
They are involuntary, often catching you unawares and greeting the world with a deafening achoo.
And while we all know to cover our mouths to shield those around us from our potential germs, a new study has revealed exactly how important that courtesy is.
High-speed images reveal droplets are propelled from a person's mouth and nose, and can jettison up to 25 feet from where the person sneezing is standing.
These droplets can harbour potentially infectious organisms, scientists at the Massachusetts Institute of Technology warned.
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Their image sequences captured using a black and white camera, recorded 1,000 frames per second.
The results show what happens every 20 milliseconds after a person sneezes.
The researchers note their images show a "turbulent cloud" erupting from a person's mouth, consisting of "hot and moist exhaled air", as well as drops of saliva.
The largest droplets were found to quickly settle within one to two metres away from the person.
But, the smaller and evaporating droplets "are trapped in the turbulent puff cloud", the scientists said.
There, they remain suspended, and, over the course of seconds to a few minutes they can "travel the dimensions of a room and land up to six to eight metres away", the experts warned.
The findings are published in the New England Journal of Medicine.