You will suffer with various symtomology at 500 ppm, or even higher ppm, that don't make you immediately, or nearly immediately, go unconscious, which is what high ppm levels do. Nausea, headache, dizziness, convulsions, increased heart rate can all be expected, and possibly last for hours, before you finally go unconscious from low-level exposure, if you do at all. There's no guarantee that what you take will put you asleep during a high anxiety situation that induces huge amounts of adrenaline in your body. AND, if the low-level exposure doesn't kill you, which has a high likelihood of happening, you'll have been exposed to CO over a lengthy time, and once you awaken, you may find it has done significant, irreparable harm to your neurological system which you'll then have to live with. If you do happen to fall asleep, you have absolutely ZERO control over how the charcoals burn, if they continue burning, if they ever burn hot enough to produce a high-level of CO in your environment. It's far, FAR better to get the environment to a certainty of lethality
before entering. Anything less than 10000 ppm does not lead to quick unconsciousness, nor quick death. If certain death scares you, perhaps ctb is not the right choice for you. This is all I'm going to say on the matter. Your life, and death, is for you to do as you will.
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