Gas sensors for measuring gas concentration; Pollutant sensors; Electric sensors; Odor sensors; Electric or electronic sensors for measuring environmental parameters namely air quality, carbon monoxide (CO) levels, ozone (O3) levels, formaldehyde (HCHO) levels, oxygen (O2) levels, nitrogen dioxide (NO2) levels, ammonia (NH3) levels, hydrogen (H2) levels, chlorine (CL2) levels, hydrogen sulfide (H2S) levels, sulfur dioxide (SO2) levels, combustibles (LEL) levels, and other toxic gaseous compou...