What I'm describing isn't air being truly trapped, as if it can't get through the mask / filter. I'm describing a phenomenon whereby most air will naturally remain within a loosely defined cavity, because the boundary (mask) prevents the local air current (e.g., caused by A/C, fan, people walking by, wind, etc.) from pushing the air immediately out from in front of your face.
You can imagine breathing in and out of a paper bag, and how that might turn out. This effect, put on a continuum with the effect produced by an N-95 mask, would be worse than the N-95 mask; however, the mechanism would remain roughly the same and both would be somewhere between "no oxygen at all" and "atmosphere level oxygen" on that continuum.
To experience what I'm describing, just put on a pulse oximeter and take a reading every 15 seconds for 5 minutes. Then, without getting up or changing your position, put on an N-95 mask tightly, wait 1 minute, then take a reading from the oximeter every 15 seconds for 5 more minutes. Add up the readings from each group and divide by the total counts in each group to get the average.
Once you've experienced this, we can then use the transitive / syllogistic logic of: if lower oxygen leads to brain damage (or lesser development) during childhood AND masks lower oxygen levels, THEN we come to the a priori conclusion that masks lead to brain damage.
What I'm describing isn't air being truly trapped, as if it can't get through the mask / filter. I'm describing a phenomenon whereby most air will naturally remain within a loosely defined cavity, because the boundary (mask) prevents the local air current (e.g., caused by A/C, fan, people walking by, wind, etc.) from pushing the air immediately out from in front of your face.
You can imagine breathing in and out of a paper bag, and how that might turn out. This effect, put on a continuum with the effect produced by an N-95 mask, would be worse than the N-95 mask; however, the mechanism would remain roughly the same and both would be somewhere between "no oxygen at all" and "atmosphere level oxygen" on that continuum.
To experience what I'm describing, just put on a pulse oximeter and take a reading every 15 seconds for 5 minutes. Then, without getting up or changing your position, put on an N-95 mask tightly, wait 1 minute, then take a reading from the oximeter every 15 seconds for 5 more minutes. Add up the readings from each group and divide by the total counts in each group to get the average.
Once you've experienced this, we can then use the transitive / syllogistic logic of: if lower oxygen leads to brain damage (or lesser development) during childhood AND masks lower oxygen levels, THEN we come to the a priori conclusion that masks lead to brain damage.