Sneezed bacteria travels farther than you think – and lasts longer
It’s cold and flu season and the sounds of coughs and sneezes are commonplace in the air.
But don’t get lax on following the well-worn advice of covering your mouth and washing your hands, because Australian researchers have discovered how far sneezed and coughed bacteria spreads and how long it remains in the air – and it’s worse than you thought.
Scientists at Queensland University of Technology found a subset of pseudomonas aeruginosa, a bacterial species associated with hospital infections, expelled from a sneeze or cough can hang around in the air for as long as 45 minutes after.
The force of a sneeze or cough can also propel the bacteria up to four metres.
This video uses high-speed imaging to show how far some cough and sneeze droplets travel after a sneeze.
"Our previous research had found that these pathogens travelled up to four metres and stayed viable for 45 minutes after being coughed into the air," Lidia Morawska, co-lead researcher and Director of the International Laboratory for Air Quality and Health, said in a statement.
"We wanted to find out how bacteria-carrying droplets expelled by sneezes or coughs travel such distances and remain able to infect other people after such a long time."
Professor Morawska said the research team found that the bacteria in the cough droplets decayed in two different time spans.
“As soon as cough droplets hit the air they rapidly dry out, cool and become light enough to stay airborne. They also partly degrade through contact with oxygen in the air, with larger droplets taking much longer to evaporate.
“We found that the concentration of active bacteria in the dried droplets showed rapid decay with a 10-second half-life for most of the bacteria but a subset of bacteria had a half-life of more than 10 minutes,” she said.
“This suggests some of the pseudomonas aeruginosa bacteria are resistant to rapid biological decay and thus remain viable in room air long enough to form an airborne infection risk, especially to people with respiratory problems such as patients with cystic fibrosis.”
So make sure next time you feel a sneezing fit coming on, full cover your mouth and wash your hands after!