The sulfur dioxide sensor (SO₂) is an electrochemical sensor which, like any electrochemical sensor, has cross-sensitivities.
In the case of the SO₂ sensor, these are the following known cross-sensitivities: most noticeable is the sensitivity to hydrogen sulfide, which often occurs indoors and is generated by human metabolism. There is also a [negative] cross-sensitivity to alcohol (e.g. from cleaning agents).
Furthermore, these types of sensors (including the SO₂ sensor) show more or less high dependencies on temperature and humidity. However, these are largely calculated out.
Electrochemical sensors must be calibrated from time to time, since the baseline (zero line) of the measured values can shift due to climatic shocks (e.g. if the self-calibration of the sensor takes effect at the moment when the temperature has just “jumped”.
This corrects itself over time through the self-calibration function, but can also be done faster in the air-Q app under “Settings – Calibration”.
See here: How do I perform a manual calibration?
