Many people wear masks in public to slow the spread of COVID-19, as recommended by the Centers for Disease Control and Prevention (CDC). However, masks with exhalation valves do not slow the spread of the disease, and now, new videos from the National Institute of Standards and Technology (NIST) show why.
Click here for original story, New airflow videos show why masks with exhalation valves do not slow the spread of COVID
Source: Phys.org