Breaking down face masks and breaths

Editor’s note: Portions of this letter were inadvertently omitted in a production error last week, so we’re reprinting it in its entirety today.

Catching up on my reading Thanksgiving night, I saw that Mr. Geshekter has fallen for some faux-science that face masks trap CO2 from your breath and could be a health hazard. Let’s see.

Human breath is only about 4% CO2 by volume and human lungs have a maximum volume of 6 litres (approx .2 cu ft).

Exhalation pushes out all air that was left in the mask from inhalation, filling it with ~4% CO2, and there is no physical or chemical mechanism for a fabric mask “of any common type” trapping or concentrating CO2.

I estimate the volume of mask material and the air spaces between the mask and the face to be around 2 cubic inches (.0012 cu ft).

Therefore each breath takes in at most .0012/.2 or .6% of your previous breath’s 4% CO2 exhalation. About as much additional CO2 as you might get walking through someone else’s exhalation.

So, if you believe rebreathing After only 4 breaths taken in a closed car (Toyota Camry, 88 cu ft cabin volume) without ventilation running, you are breathing that same percentage of CO2; and it is increasing linearly with every breath you take.

Please, please, please put on your high school math and science thinking cap before turning on Fox Noise. Or, as the kids say, “review BEFORE you spew.”

— David Fundakowski, Chico