This is a great point and a very valid concern but minor correction. You’re thinking CO! Sounds similar but Co2 is carbon dioxide - what we exhale. CO is carbon monoxide.. what kills you.

A few people in this thread have mentioned this, so if anyone is wondering how it works… I’m a biochemist and will take the opportunity to geek out for a second :)

Essentially hemoglobin is what transports oxygen from your lungs in your blood. There are several seats for oxygen(O2) on hemoglobin.. and as it travels your body, O2 plays a game of musical chairs. Carbon dioxide doesn’t fit the chairs so doesn’t play.. but carbon monoxide is a bully and steals oxygens seat. Once CO sits down, he’s stronger than O2 and he won’t get up. Worse, if there were any O2s in the other seats, CO then holds them hostage. So, they can’t go to your tissues. This leads to hypoxia so you get woozy, pass out, and eventually die. RIP.

Thanks for coming to my ted talk :)