Formaldehyde belongs to the group of volatile organic substances. Volatile Organic Substances (VOC) are measured by means of a resistive sensor.
Molecules “docking” on the surface of the sensor cause a change in electrical resistance in the sensor.
The VOC sensor thus reacts to many substances, including odors, alcohol, cleaning agents, disinfectants or combustible gases such as methane, also formaldehyde and other solvents.
Unfortunately, however, the sensor cannot distinguish formaldehyde from the other substances mentioned; it only outputs a specific VOC value.
However, you can track the progressions very well with the air-Q and thus narrow down the sources. In this way, the substance can also be narrowed down – if the VOC value increases, e.g. overnight or when the room is not in use, certain gases / sources can be excluded until ultimately only a few remain. So it often comes out that high VOC values are directly human-caused (breathing, release of gases through the skin) or also the existing fruit bowl or the trash can are the reason.