H2S monitors are not much of a concern where the oil industry isn’t big. If you do linework in West Texas, for example, you will probably be issued on. This little device will start going absolutely nuts when it detects harmful gases that are prevalent in and around the oil field. If you’re required to wear one, clip it to your shirt about 6″-8″ from your face. Not your boot, hard hat, lunch box, pocket, etc. H2S has no odor and it will sneak up on you. This device is the only thing that is able to let you know you’re about to die.
Side note: you can set off an H2S monitor by farting on it. Don’t ask me how I know that.