Carbon monoxide is produced whenever combustion is incomplete, and its hazard comes as much from its invisibility as from its chemistry. OSHA sets the permissible exposure limit at 50 ppm as an 8-hour time-weighted average, with a ceiling of 200 ppm. NIOSH places the immediately dangerous to life or health threshold at 1,200 ppm — a concentration that can be reached within minutes in a poorly ventilated enclosed space. The gap between those two numbers is where industrial CO incidents tend to happen: slow enough that workers don't notice until symptoms appear, fast enough that there's little time to respond once a process goes wrong.
The case for fixed detection over portable monitoring comes down to one thing: fixed systems don't depend on human behavior. Portable detectors are appropria ...
