3 ms·

Exhaled breath is about 3.8% or 38000ppm so (20000) that's really high! I'm not too surprised since the turnover rate through a few small holes with a relativel

by kurthr 8y ago

Exhaled breath is about 3.8% or 38000ppm so (20000) that's really high! I'm not too surprised since the turnover rate through a few small holes with a relatively large volume is bad. Reducing the facial volume would help a lot as each breath would expel more CO2 as a fractional percentage. It seems that any sort of face covering or even significant exercise could raise your ambient CO2 level well above 1000ppm. I'm a bit surprised that levels 38-60x below our exhalation % (and it's not lack of O2, because you use up less than 10%/breath) has such a significant effect. The one thing that may drive it is that the efficiency of lung ab/desorption goes roughly as the square of concentration so a 2% change in CO2 concentration might be enough to have an effect on O2 and blood pH.

Klathmon 8y ago
I found the study I read, and I'll re-link it here, it is eye opening to say the least! https://www.ncbi.nlm.nih.gov/pubmed/15893291 https://www.ncbi.nlm.nih.gov/pubmed/15893291
- kurthr 8y ago
  Really interesting article... all the numbers are completely believable, but seem really high based on the conference room effects at 0.1% They even refer to a person without a helmet in still air as being at 2000ppm, which is comparable to the worst tested "school house" data. I'd argue that if there is an effect here it isn't the O2 concentration since a 1% change in atmospheric pressure happens at about 275ft. That's a pretty small hill! A 1000ppm change in 02 partial pressure happens in about 30C temperature change. Really, if this is a real effect it better be actually due to some effect of C02 concentration.
- inetknght 8y ago
  Is there a link for the Elsevier-disabled people?
  - Vinnl 8y ago
    Unfortunately Unpaywall (tip: install the browser extension!) doesn't find any: https://unpaywall.org/10.1016/j.apergo.2005.01.018 https://unpaywall.org/10.1016/j.apergo.2005.01.018 So unless you're willing to go the illegal route through Sci-Hub, I'm afraid you're out of luck.
  - deepsun 8y ago
    SciHub has it

by kurthr 8y ago

Klathmon 8y ago

I found the study I read, and I'll re-link it here, it is eye opening to say the least! https://www.ncbi.nlm.nih.gov/pubmed/15893291 https://www.ncbi.nlm.nih.gov/pubmed/15893291

kurthr 8y ago
Really interesting article... all the numbers are completely believable, but seem really high based on the conference room effects at 0.1% They even refer to a person without a helmet in still air as being at 2000ppm, which is comparable to the worst tested "school house" data. I'd argue that if there is an effect here it isn't the O2 concentration since a 1% change in atmospheric pressure happens at about 275ft. That's a pretty small hill! A 1000ppm change in 02 partial pressure happens in about 30C temperature change. Really, if this is a real effect it better be actually due to some effect of C02 concentration.
inetknght 8y ago
Is there a link for the Elsevier-disabled people?
- Vinnl 8y ago
  Unfortunately Unpaywall (tip: install the browser extension!) doesn't find any: https://unpaywall.org/10.1016/j.apergo.2005.01.018 https://unpaywall.org/10.1016/j.apergo.2005.01.018 So unless you're willing to go the illegal route through Sci-Hub, I'm afraid you're out of luck.
- deepsun 8y ago
  SciHub has it