What is the relative size of the coronavirus relative to a CO2 molecule. If masks don’t stop a virus from passing, why would they stop a CO2 molecule?
Most of the air exhaled escapes the mask, but the air that remains in the mask before the next breath has lowered oxygen content and increased CO2 content.
The next inhale pulls fresh air into the mask and mixes it with this excess CO2 from the previous exhale. You lungs now fill with air with a reduced oxygen content and increased CO2 content.
Each breath you take repeats this increase in CO2 and reduction of oxygen that actually gets into your lungs. The longer you wear the mask, the worse this imbalance becomes.
This one is easy to check for yourselves.
Get yourself a cheap Pulse Oxymeter from your local pharmacy. ($15-$30+)
Put it on your finger and check your blood oxygen level.
Now put on your favorite mask, and just breath for a while.
Note your %SpO2 level after 5 minutes, 10 minutes, 15 minutes, 30 minutes.
I did this test on myself. My normal %SpO2 is 96% and my resting heart rate is about 62 bpm.
After 10 minutes walking slowly around my house with the procedure mask on my %SpO2 was 88% and my pulse was 85bpm.
I took the mask off, breathed deeply, and watched the %SpO2 rise to 94% within 20 seconds.
Finally, keep in mind that the excess CO2 in your lungs is probably more serious than the shortage of oxygen.