Skip navigation
I had indicated I would try to test whether masks cause us to increase our CO2 intake so here are my results and thoughts. I noticed when I am wearing a mask, I am re-breathing some of my exhaled air, simply by the fact that inhaled air in a mask is hotter than fresh air without a mask. When a person breathes in air it is roughly 78 percent nitrogen, 21 percent oxygen and 0.04% CO2. We exhale  a mixture of compounds which is roughly 78 percent nitrogen, 16 percent oxygen, 0.09 percent ar ...