Your description of the IAQ accuracy is not totally correct. The IAQ accuracy is actually reflecting the current state of the background calibration process, such as: IAQ Accuracy=0 could either mean: BSEC was just started, and the sensor is stabilizing (this lasts normally 5min in LP mode or 20min in ULP mode), there was a timing violation (i.e. BSEC was called too early or too late), which should be indicated by a warning/error flag by BSEC, IAQ Accuracy=1 means the background history of BSEC is uncertain. This typically means the gas sensor data was too stable for BSEC to clearly define its references, IAQ Accuracy=2 means BSEC found a new calibration data and is currently calibrating, IAQ Accuracy=3 means BSEC calibrated successfully. Therefore to answer your questions: The effective duration of the calibration process depends on the stimuli observed by the sensors. See the definiton above. This also means that an IAQ accuracy going back and forth between 2 and 3 is expected, and that BSEC is successfully recalibrating itself. As defined above, an IAQ accuracy of 2 while the IAQ output is below 25 typically means BSEC is currently calibrating. If the current environment remains stable long enough, the IAQ output should go back to around 25.
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