To select the correct BSEC output to use, we recommend that you ask yourself these questions (in order):
Can I use the IAQ output, or base my algorithm on it to fulfill my use-case ? Use IAQ output. (For most mobile applications such as a PERSONAL air quality monitor, this is the best option)
Can I use the static IAQ (sIAQ) output, or base my algorithm on it to fulfill my use-case ? Use sIAQ output, or its derivatives, such as CO2 or bVOC estimation. (For most static applications, such as smart home or HVAC, this is the best option)
Can I develop an algorithm based on the compensated gas resistance value ? Use compensated raw resistance. Some knowledge of MOX sensing technology is required, especially for baseline tracking, but you can leverage the humidity and temperature compensation from BSEC. This output is a gas resistance value in ohms after removing the effect of humidity and temperature.
The CO2 and bVOC equivalent estimations, are derived from the sIAQ signal and provide an estimation of the gas concentration in ppm, making the assumption that the source of pollution is from human breath, and that the sensor is used indoors.
For the temperature and humidity signals, when using the ULP mode, these can be used directly. In LP mode, the sensor will generate some heat which can artificially increased the raw temperature and decrease the humidity. This effect is compensated when using the heat compensated outputs.