That is why I uploaded the variation in IAQ in the three graphs above, you can see that as CO2 levels drop the IAQ rises, why is that? It seems there is something strange with the BSEC algorithm, which is why I am asking if the BSEC has been validated with various test cases, for example when CO2 levels are high, low, or that the results are consistent with other sensors. I have not seen any material published to determine the validity of the results... SAGP40 VOC results BME IAQ Results Both sensors are in close proximity with the SCD41 refrerenced above, so two sensors are showing simialr results, but in all scenarioes the IAQ value response is the inverse of poor air quality. This is the SGP40 result versus the BME680 BSEC result for IAQ, note how as the SGCP40 sensor detects a lowering VOC, the BSEC results start to increase, this cannot be correct and it looks like there is an inversion in the BSEC library.
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