4 ms·

As someone who wears a kn95 mask all day I think the results of linked study should be taken with a grain of salt. The CO2 concentrations they measured with con

As someone who wears a kn95 mask all day I think the results of linked study should be taken with a grain of salt. The CO2 concentrations they measured with conventional masks are effectively similar to the concentrations in exhaled air, which means they may only be measuring the concentration in the stale air sitting inside the mask between each inrush of fresh air that occurs with each inhalation. In other words, I don't care what the CO2 concentration is in my mask. I care what the average concentration is in each inhaled breath, which consists of the stale air in my mask, combined with the (presumably larger volume of) fresh air that is introduced by breathing in. I doubt the study methodology properly captured that.

giantg2 5y ago
That's largely irrelevant if you look at the constraints of the system we are discussing. 1- the beneficial level in the article is to keep CO2 under 800ppm for learning benefit. 2- tidal volume in adults is 400-500ml. 3- volume inside an N95 varies based on model and face geometry, but is presumably 20ml or much larger, especially for children with smaller faces. 4- indoor CO2 concentrations are typically not lower than 600ppm. Based on this info, average concentration easily exceeds 1000ppm. This is even more likely for children who have smaller tidal volumes and presumably more volume under the mask.
- vertnerd 5y ago
  I think your take is fine, but it's a far cry from saying we're spending the day at the 15 minute limit for CO2 concentration. The classroom I teach in easily hits the 1000 ppm level (I measured it at the start of the 2020-21 school year), so we're already suffering before the masks go on. The masks just make it a little bit worse.
- jve 5y ago
  > 4- indoor CO2 concentrations are typically not lower than 600ppm. Out of curiosity, just looked at my PPM monitor behind my laptop... it reads 600 :) We have a good ventilation here. But humidity suffers (very low)

giantg2 5y ago

That's largely irrelevant if you look at the constraints of the system we are discussing. 1- the beneficial level in the article is to keep CO2 under 800ppm for learning benefit. 2- tidal volume in adults is 400-500ml. 3- volume inside an N95 varies based on model and face geometry, but is presumably 20ml or much larger, especially for children with smaller faces. 4- indoor CO2 concentrations are typically not lower than 600ppm. Based on this info, average concentration easily exceeds 1000ppm. This is even more likely for children who have smaller tidal volumes and presumably more volume under the mask.

vertnerd 5y ago
I think your take is fine, but it's a far cry from saying we're spending the day at the 15 minute limit for CO2 concentration. The classroom I teach in easily hits the 1000 ppm level (I measured it at the start of the 2020-21 school year), so we're already suffering before the masks go on. The masks just make it a little bit worse.
jve 5y ago
> 4- indoor CO2 concentrations are typically not lower than 600ppm. Out of curiosity, just looked at my PPM monitor behind my laptop... it reads 600 :) We have a good ventilation here. But humidity suffers (very low)