by K. Richard, August 20, 2018 in NoTricksZone
by Blair King, April 10, 2016
Specifically the Bureau of Land Management Health Risk Evaluation for Cabon Dioxyde points out:
A value of 40,000 ppm is considered immediately dangerous to life and health based on the fact that a 30-minute exposure to 50,000 ppm produces intoxication, and concentrations greater than that (7-10%) produce unconsciousness (NIOSH 1996; Tox. Review 2005). Additionally, acute toxicity data show the lethal concentration low (LCLo) for CO2 is 90,000 ppm (9%) over 5 minutes (NIOSH 1996).
See also The Lake Nyos Disaster
See also here