What affects sensor readings?

According to SIIAQ (Italian Society of Indoor Air Quality), sensor readings could be affected by the following variables:

1. Number of people present, their activities, and their dwell time
2. Type of materials present, their emission certifications, paints and varnishes used
3. Room size and location of radiators/heating elements, location of bathrooms, presence and location of elevators or other facilities, etc.
4. The plant characteristics and the manner in which the necessary air exchange is carried out (e.g., natural ventilation or VMC, controlled mechanical ventilation)
5. The manner and frequency of cleaning (e.g., type of broom and/or vacuum cleaner, use of microfiber cloths, type of detergents used, possible use of insect and pest repellents, etc.)
6. Possible presence of issues such as peeling paint, presence of dirt or debris, stains from water damage (e.g., walls, ceiling tiles, etc.), moisture on surfaces (e.g., condensation on windows), malfunctioning fixtures, etc.
7. Incorrect placement (see this FAQ for correct placement)