I hear a lot of people using dry ice, yeast and sugar, CO2 cartridges...

but how effective would it be to just close windows more often?

I heard CO2 levels are about twice the amount of CO2 outdoors.

Also what about filling up bags of exhaled CO2?

I know it sounds silly but don't humans and living being exhale a lot of CO2?
Revanche21 Reviewed by Revanche21 on . CO2 from exhaling I hear a lot of people using dry ice, yeast and sugar, CO2 cartridges... but how effective would it be to just close windows more often? I heard CO2 levels are about twice the amount of CO2 outdoors. Also what about filling up bags of exhaled CO2? I know it sounds silly but don't humans and living being exhale a lot of CO2? Rating: 5