In this case, your air purifier indicates the current quality of the air by displaying a red or green light.
In the first few minutes after you select the SmartAir Control function, the air quality indicator will flash red to indicate that the air quality sensor is measuring the ambient air quality. After approximately 5 minutes, the air quality indicator lights up green if the air quality is good or lights up red if the air quality is poor.
Note: The SmartAir Control function is only applicable for purifiers AC406x. For these purifiers, this function automatically adjusts speed settings according to the current air quality.