The gas sensors (carbon dioxide, VOC, nitrogen dioxide and ozone) require a warm up period during first time use. The carbon dioxide sensor requires at least 48 hours of continuous use for it to complete the warm up, while the VOC, nitrogen dioxide and ozone sensors require at least 24 hours of continuous use.
If the warm up is interrupted (device turned off, power failure or lower fluctuation), the warmup will restart from the beginning and will need another 48 hours or 24 hours, depending on which gas sensor. This warm up needs to be conducted only once.
During the warmup period, the readings will fluctuate and you can ignore the data. Once the warmup is completed, your readings will automatically adjust.
Your uHoo also has auto calibration technology. This technology was developed to ensure the long term performance of the sensors. Auto-calibration happens every 168 hours of continuous use. The CO2 sensor would need at most 3 cycles of auto calibration to achieve full accuracy. Whenever the device is switched off then switched back on, the VOC, nitrogen dioxide and ozone sensors will only start sensing your air after 30 minutes. During the first 30 minutes, they will remain at very low levels.