Six feet of physical distancing may not be enough to slow the spread of viruses if someone coughs in your direction, according to a new study from Western University.
Researchers examined how far an unobstructed cough could travel and how fast its droplets moved using people infected with the flu during the 2017-2018 influenza season. Analyzing the coughs in a specialized "cough chamber", researchers found droplets would reach a person standing the recommended six feet away within three seconds.
"Even when you are 2.5 metres (eight feet) away, the airflow in the cough can still be moving at 200 millimetres a second,” said Eric Savory, from Western's department of mechanical and materials engineering. “That means the very fine droplets are going to remain suspended for a long time, even after four seconds."
Approximately 10 per cent of cough droplets are still in the air six feet away, the study found.
Health officials around the globe have recommended people maintain a physical distance of six feet to limit the spread of the coronavirus.
A camera and laser were used in the cough chamber to determine the velocity of the expelled droplets.
Savory, who worked with virologists at Sunnybrook Hospital in Toronto for the final analysis, believes the study marks the furthest distance anyone has ever measured cough airflow. He is now working on transitioning his findings to help public health and government officials battling the COVID-19 pandemic.
The research team, which also includes Eric Arts from Western’s Schulich School of Medicine & Dentistry and Franco Berruti from Western’s Department of Chemical and Biochemical Engineering, will now be examining the pathways of COVID-19 droplets through the air. They will also analyze different surfaces to verify the viruses survivability under different temperature and humidity conditions. The additional testing will be conducted in the same lab where other Western researchers are working to develop a COVID-19 vaccine.
The findings of the cough study were recently accepted for publication in the scientific journal Indoor Air.
