Yep, what most people forget when talking about N95 and similar is how a "standardized" fit test is performed, basically the 95% is theory and only IF the mask is properly fitted.

You will have deep signs on your face after wearing a fitted N95 a feww hours.

Previous posts with some more details and link to a US Department of labour video: https://news.ycombinator.com/item?id=27129984 https://news.ycombinator.com/item?id=23957506