Covid-19 : LaVision imaging technique shows how masks restrict the spread of exhaled air

The primary way of person-to-person corona virus transmission is via aerosols or small droplets created by breathing, sneezing or coughing. The reach of exhaled air can be effectively reduced using a face mask as shown in the video. A simple Schlieren imaging technique is applied to visualize the air flow caused by a person breathing and coughing. Using a face mask the exhaled air flow is blocked reducing effectively the risk of infection. Also nicely shown is the heat transfer from the body to the cooler ambient air. More information about the Schlieren imaging technique is given here: