General Monitors? hydrogen sulfide (H2S) sensors are solid state devices, designed and manufactured for long life and fast response. They are selective to H2S and remain unaffected by high concentrations of other substances like hydrogen, sulfur dioxide, and gasoline vapors, which are often present in facilities that process sour gas and crude oil. A high tolerance to a broad range of temperatures and humidity enable these sensors to operate in rugged environments, as does their capacity to withstａnd exposure to high H2S concentrations over short periods.