Germaphobes, prepare to become shut-ins: Researchers have found that some bacteria expelled into the air by a sneeze or a cough can live for up to 45 minutes. That means you can enter a space that a sick person has vacated nearly an hour earlier, and still pick up their bug. Worse, the bacteria can disperse a distance of 10 feet or more beyond its origin.
A team of Australian researchers focused on a subset of pseudomonas aeruginosa, a bacterial species associated with hospital infections. Healthy people can reduce their chances of infection by washing their hands after spending time in public spaces. The pseudomonas aeruginosa bacteria, however, is more dangerous to people with compromised immune systems and particularly to those with cystic fibrosis. These new findings suggest that a person could enter an empty room and catch a bug from someone they don’t even see or have contact with if the sick person recently vacated the space.
“Our previous research had found that these pathogens travelled up to 4 meters [more than 13 feet] and stayed viable for 45 minutes after being coughed into the air,” said Lidia Morawska, a co-lead researcher at the Queensland University of Technology (QUT).
“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.”
The QUT team developed a method called Tandem Aged Respiratory Droplet Investigation System, or TARDIS (not that TARDIS), to study aerosols, the airborne droplets generated by a human cough or sneeze. They noted that the droplets dry out quickly and become light and airborne. While most of the bacteria died within seconds, some of them survived much longer.
“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,” said Morawska.
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