How long can you wear a KF94 or KN95? How to get a good face fit and more!

Using my mask test setup I attempt to answer the question of how long these can be used for. Also in this video I cover some ways to get a good face fit, the latest Danish Mask Study and more. 00:00 - Intro 1:45 - “How long do you recommend wearing a mask?“ 2:20 - Used mask filtration efficiency test #1 4:28 - Test #1 data 5:53 - Worst case scenario mask test results 7:50 - “Do you recommend cleaning masks with isopropyl alcohol?“ 9:18 - “What if my mask gets wet?“ 9:57 - Used mask filtration efficiency test #2 11:05 - Test #2 data 14:09 - “Why does filtration efficiency decrease after use?“ 16:28 - “What does a good face fit feel like?“ 19:13 - “Why are my glasses still fogging up?“ 21:07 - “What is the risk of contracting coronavirus from a mask?“ 23:49 - “How do you recommend I handle and store my mask after use?“ 27:11 - “Do you recommend cloth or surgical masks?“