Scientists have discovered that it takes just a single sneeze from a flu sufferer to spread germs around an entire room.
And the contamination can last for hours, they say.

Researchers have found that the microscopic infected droplets emitted in a cough or sneeze float around the air in large enough concentrations to spread disease.
Breathing in airborne specks of virus found in a typical office, doctor’s surgery, plane or train could infect a person after just one hour.
The discovery gives a ring of truth to the old advice that you should never visit a doctor’s waiting room unless you want to get sick.

It also highlights why so many holidaymakers pick up coughs, colds and sniffles at the start of their trip, following a flight.
Flu passes from person to person through direct physical contact, or when someone sneezes or coughs.
Most studies have concentrated on large droplets, known as aerosols, that carry the virus in the air but which quickly fall to the floor and nearby surfaces.

Few studies have looked at the threat from the smaller droplets, which can remain airborne for hours or even days.
U.S. researchers at Virginia Tech collected samples of air from the waiting room of a healthcare clinic, three rooms in a nursery and three cross-country flights.
Half the samples contained small droplets containing the flu virus.
The scientists found that a typical cubic metre of air contained an average of 16,000 particles of flu virus. Most were less than 2.5thousandths of a millimetre across, which remain suspended in the air for hours on end.
‘Given these concentrations, the amount of viruses a person would inhale over one hour would be ­adequate to induce infection,’ said Dr Linsey Marr, who led the study, published in the Journal of the Royal Society Interface.

A typical cough shoots out jets of air several feet long, along with around 3,000 droplets of saliva at speeds of up to 50mph.
Sneezes typically contain as many as 40,000 droplets, some which leave the body at more than 100mph.