These monitors are equipped with a siren that goes off when the oxygen level gets too low. That's what this father did. He tested without the mask and then with the mask, the alarm sounded.
Ah thanks. That is a good start, but should also somehow monitor the actual air quality for pathogens that make it through the mask too. Or doctors could take used dirty masks and hook them up to some kind of breathing machine for testing purposes, and test the quality that way perhaps. I’m betting it won’t look pretty, the stuff getting through the masks I mean.
The typicsl,typical, wears their masks continuously, for days, sometimes weeks and even months, so the tests should study masks with concentrated levels of pathogens on them to represent what people are actually breathing through