I’m always fascinated with the goofs who think that .04% of something can’t be a problem, and here we are with a living example
200 ppm is 0.02%
“Carbon monoxide becomes deadly at high concentrations, with severity increasing based on both the concentration level and duration of exposure. Generally, concentrations of 200 parts per million (ppm) or greater can cause severe symptoms and be fatal within hours[1]. At 12,800 ppm, carbon monoxide levels are fatal within just 1-3 minutes[2].”
