Air monitoring equipment can be a permanent installation or portable units designed to detect one or more hazardous atmospheric sitatuions. The most common is a handheld 4-gas detectors or monitors, are used to determine the concentration of Oxygen (O2), Hydrogen sulfide (H2S), Carbon monoxide (CO), and the Lower Explosive Levels (LEL) of a variety of combustible gases.
While no monitoring equipment is going to detect every possible hazardous chemical, an important consideration is any variation from the 20.9 percent Oxygen concentration in air. If the concentration is below the 20.9, that indicates that something else is displacing that Oxygen and it might not be picked up by the other sensors.
