Review on Dioxide Detector Formaldehyde Quality Analyzer by Junrey Jewel

Some important information about this product is missing from the online description (see uploaded photos ). As long as you know that the measurements are up to 30% inaccurate and the measurements are only there to give you a rough idea of air quality, this seems like a good number. An error of up to 30% is a high level of uncertainty. There is a calibration button (press the "+" button for 5 seconds) "to calibrate", but there are no instructions on how to use this function. Does it have to be placed in a known environment when this key is pressed? The CO2 levels I measure in my home (350-550ppm) seem reasonable, and it responds to controlled changes like placing a lit candle nearby or leaving a room. in the room. I bought this unit to determine if the HVAC air exchange was adequate. The CO2 content can be used as an indicator of stale air.