Thats the first thing I though of also
Michael,
I don’t know where that website got its numbers but here are numbers that are internationally recognized.
ASHRAE 9ppm over 8 hours
WHO 15-20 ppm causes impaired performance
25 ppm Max allowed in parking garage (IMC)
WHO 30 ppm increase in cardio respiratory complaints
US NIOSH 35 ppm recommended 8 hour workplace exposure
US OSHA 50 ppm recommended 8 hr maximum wotkplace exposure
BPI 35 ppm and auditor leaves building
While I do recognize it may take 200 - 400 ppm for 1 - 2 hours for headaches, etc do you really want to wait for the sugns of symptoms?
Robert.
Same numbers
The higher level is for toxicity over 4 hours not 8.
Thanks guys,
(Got to love this International Association of Certified home inspectors message board).
Good reading and good references.
I have been recommending CO2 for a while, I even have and use one at home.
Salut,
Beauchemin,Marc-Andre 
It’s CO Mark, not CO2
Mike,
Re-read Marc’s post. *Maybe *he does use CO2 at home! :shock:
Jeff, Maybe he has a sodastream unit. 
I use a couple of five gallon soda kegs set at 8psi so the beer has proper co2.