The cough
The average human cough would fill about three-quarters of a two-liter soft-drink bottle with air — air that shoots out of the lungs in a jet several feet long. Coughs also force out thousands of tiny droplets of saliva. About 3,000 droplets are expelled in a single cough, and some of them fly out of the mouth at speeds of up to 50 miles per hour.
The sneeze
Sneezing is even worse!
It starts at the back of the throat and produces even more droplets — as many as 40,000 — some of which rocket out at speeds greater than 200 miles per hour. The vast majority of the droplets are less than 100 microns across — the width of a human hair. Many of them are so tiny that they cannot be seen with the naked eye.
Airborne and ready to infect
Once airborne, viruses in these tiny droplets can survive for hours. Even if the droplets hit a surface, the viruses can survive and still spread disease if the droplets become airborne later. When a droplet lands on paper, its virus particles can survive for hours. On steel or plastic they can survive for days.
Read more in “The Gross Science of a Cough and a Sneeze”
Previous: Wednesday Wonder #8: Smelly Feet