CH4 is also dangerous. It's a different problem. CH4 blows up your house and is very rare. CO kills you and is very rare. CO2 buildup causes mild issues (like h

CH4 is also dangerous. It's a different problem. CH4 blows up your house and is very rare. CO kills you and is very rare. CO2 buildup causes mild issues (like headaches, sleepiness) but is very common.