[Grandpa Drudge]

The mask does indeed reduce oxygen and increase CO2 in the air inhaled into the lungs.

Please see my reply to oincobx (post 118, above) to understand how and why this is true.

I even include a simple way to test whether the effect of this is serious for you or not. The severity is different for different people in different environments (such as altitude, health etc.)

For me, the effect is quite severe.

[alexander_busek]

Please see my reply to oincobx (post 118, above) to understand how and why this is true.

I, of course, understand that a very small amount of exhaled air (which will, of course, contain a few percent of CO2) is "trapped" in the space between the mask and your face, and will hence be re-inhaled.

I just didn't think that this small amount of CO2 was significant. Didn't ponder the effects of multiple re-inhalations, though - so you are right and I concede that I was too hasty in my objections. (Say, is that a Free Republic "first?")

Regards,