Don’t cough into a bare elbow — it doesn’t stop viruses, study says. Do this instead
For many, it was taught at a young age that coughing into your elbow is more responsible than coughing out in the open or into your hand. But new research says that method may not be a great alternative after all, especially during the coronavirus pandemic.
In a visual experiment using photos to capture the motion and density of coughs under different scenarios, researchers found that a bare elbow does not provide “a proper seal against airflow from the nose” and mouth. Coughing this way allows potentially contaminated respiratory droplets to escape in many directions, the research showed.
What the team did find is that an elbow armored with a loose fitted long sleeve does a much better job at “reducing the ejection of cough air into the atmosphere,” according to their study published Tuesday in the journal Physics of Fluids.
Of course, their suggestion to cough into a sleeve applies only when masks are unavailable.
“Even if a mask does not filter out all the particles, if we can prevent clouds of such particles from traveling very far, it’s better than not doing anything,” Dr. Prasanna Simha Mohan Rao, from the Sri Jayadeva Institute of Cardiovascular Sciences and Research in India, said in a news release. “In situations where sophisticated masks are not available, any mask is better than no mask at all for the general public in slowing the spread of infection.”
Because coughs tend to be warmer than surrounding air when expelled, the researchers used a technique called schlieren imaging that uses photos to capture and measure the flow of fluids and their densities. They tracked the motion of coughs over successive images to estimate their velocity and spread.
The team had five people voluntarily cough in nine different scenarios: no mask, a surgical mask, N95 mask, into their bare hand, into cupped hands, folded handkerchief over the mouth, surgical mask plus their hand covering their mouths, elbow with a sleeve and elbow without a sleeve.
Like other studies have shown, cough droplets expelled with no mask were able to spread about 5 to 10 feet forward; with a surgical mask that distance drops to about 1.5 to 5 feet, while N95 masks blocked droplets from traveling less than a foot.
But in the absence of an N95, surgical or cloth mask, the experts suggest using a folded handkerchief over your mouth or a covered elbow to cough into.
The Centers for Disease Control and Prevention says coughing or sneezing into your hands is the last resort; doing so will immediately put any objects or people you touch at risk of contamination with potentially infectious germs. Instead, use your elbow.
If coughing into a tissue, make sure to throw it in the trash right away, the CDC advises.
This story was originally published August 26, 2020 at 2:48 PM with the headline "Don’t cough into a bare elbow — it doesn’t stop viruses, study says. Do this instead."
