NIST airflow videos - valved and unvalved masks and various face coverings

[Mitz]

There's 3 videos. One at the top, one half way down and one at the bottom in the related videos section. Shows the airflow from valved and non-valved masks along with various face coverings as the wearer exhales.

https://www.nist.gov/news-events/ne...hy-masks-exhalation-valves-do-not-slow-spread