... up time72 hours (first time), 10 mins (normal operation)VOC measuring range0~30ppm ( 1ppm= 1 part per millionDisplay resolution0 ... colors backlit switch as well Buzzer alarmAlarm starts when VOC value above 22ppmLCD backlitGreen—optimal air quality enjoy the ... years long life Gas detection: cigarette smoke, volatile gas like VOC, formaldehyde, toluene, ethanol, ammonia, hydrogen sulfide, sulfur dioxide ...