Will a humidifier affect the air quality indicator on the Xiaomi Smart Pet Care Air Purifier?

Yes, it will. Using a humidifier can affect the air quality indicator on the Xiaomi Smart Pet Care Air Purifier. Ultrasonic humidifiers work by atomizing water into fine mist particles, and the concentration of these particles can sometimes be quite high. The air purifier's particle sensor is highly sensitive and will detect even the smallest water particles in the air. As a result, the sensor can register higher than normal readings, or in some cases, the values can exceed the sensor’s scale. Once the humidifier is turned off, the sensor readings will gradually return to normal as the mist dissipates.
This is a common occurrence and does not indicate a malfunction of the air purifier.