The uHoo unit needs to warm up first. The VOC reading will stay 0 for the first 30 minutes upon switching on.
Not necessarily. Usually, during the warm up period, carbon dioxide levels could be high, as the sensors are still in calibration. It should normalize after the warm up period.
Not necessarily. Most times, when the VOC readings are high, it means that there is a significant amount of VOCs in the air. Did you recently use a hairspray, insecticide, or cleaning products? These can cause the VOC readings to be high.