New videos show how the N95 masks with an exhalation valve doesn’t actually stop droplets that can spread Covid-19.
The videos along with an accompanying research article published in the journal Physics of Fluids show how the airflow patterns differ between masks with and without exhalation valves.
“When you compare the videos side by side, the difference is striking,” National Institute of Standards and Technology (NIST) research engineer Matthew Staymates said. “These videos show how the valves allow air to leave the mask without filtering it, which defeats the purpose of the mask.”
To test out how the N95 mask with an exhalation valve stood up to a mask without a valve