I haven't heard that 30 minute figure before, you have a reference? I've seen articles about medical workers using masks for much longer.

Installing air filtration and UVC in classrooms and meeting rooms certainly helps.

Since the mask shortage cleared up, HCW have been advised to stop re-using them. I re-use mind til they get dirty, but maybe I should replace them more often.

https://apnews.com/article/fda-n95-masks-plentiful-should-no... (2021)

2021 reddit thread: https://old.reddit.com/r/Masks4All/comments/lhnj10/one_of_th...