When I was testing it, I was not trying to die then. I just laid everything beside me in the bed. I did everything following the instructions but just holding the mask. As soon as the bag was complete, I h I got the worst headache I've ever had. I sat there and hyperventilated for two minutes, and then my head was clear. There is no doubt if it had been hooked to my face securely, I would've died. HEld the mask to my face and hooked it up, holding it in place. Exhaled took in my first. Breathe and dizzy. Second, breathe, no change. Third, live, I dropped the mask. More like yanked it away. SI definitely kicked in. I got the worst headache I've ever had. I sat there and hyperventilated for two minutes, and then my head was clear. There is no doubt if it had been hooked to my face securely, I would've died.