28 ms·

Masks are a small volume though. Wouldn't you need to be breathing shallowly or otherwise have compromised lung capacity to make a noticeable difference? Seems

• clnq 3y ago
  Hmm, yes, that's an important factor. Let's say the average CO2 concentration in a mask is 19000 ppm (mid-point of 8000 ppm and 30000 ppm). If only 5% of the air inhaled by volume is from the mask and 95% is from outside air (440 ppm), then the average CO2 content of that inhaled air would be around 1350 ppm. I would say that's at the limits where CO2 starts to affect our mental acuity. If 95% of the air is typical office air (at about 900 ppm), then the inhaled air would be at about 1800 ppm. That is where most people would probably feel the high CO2 concentration if they knew the feeling. If the 5:95 split is correct, it would seem that wearing a mask could increase the inhaled air CO2 content by around 2-3x. It could be more or less depending on some factors. But in orders of magnitude, it would seem closer to 2.5x than 25x or 250x. This lines up with my experience. Maybe the air in an N95 mask I would wear for several hours indoors would feel even worse than 1800 ppm. But there are many factors to how inhaled air feels, including temperature and humidity. So I'm happy with 1800 ppm as an estimate. Someone should build real experiment for this and get some hard numbers. It could be a topic for a nice and times-relevant publication in respiratory health or for someone in general practice.