Sticking a square thing to your face and hope for a proper seal seems to bit optimistic. Even the image with that officer seems like badly photoshopped.

Even with proper masks, the fit is really important. Companies with proper OSHA procedures will let their employee's test fit masks with a stimulant to make sure the user gets the correct mask that works for them.

In all cases, masks without overpressure (blower or SCBA) requires a properly shaved faced.
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