consider breathing in your own respiration adding moar density w/2 useless masks. infecting and reinfecting yourself w/virus's/bacteria/germs and even less O2 intake, while sucking in moar CO2. then comes the lung infections and other pathologies.
common sense, which most people, based on the numbers falling for this shit, don't have much of.
i'm baffled at the abject naiveté and ignorance.