recent study at the University of Western Ontario in Canada examined the movement of droplets produced by a cough. Using a “cough chamber,” the researchers found that 2 meters (6 feet) is not necessarily enough distance to prevent droplets from reaching another person.
As study co-author Prof. Eric Savory explains: “If you’re a couple meters away from someone who coughs unobstructively, then within about 3 seconds or so, their cough has reached you — and is still moving. Even when you’re 2.5 meters away, the airflow in the cough can still be moving at 200 millimeters per second.”
The study also showed that around 10% of the droplets are still in the air 4 seconds after the cough. The research is yet to be published, but the journal Indoor Air has accepted it for publication.
Prof. Savory says: “There is no real logical reason for saying that 2 meters is somehow safe, but it’s much better than 1 meter or closer. We’re not saying you’re going to get infected; we’re just saying there is a risk there. Obviously, it decreases the further you are away.”