Usually HEPA filters are white in colour but the Xiaomi 3H and 3C comes with a gray coloured filter. If you want a picture, there is plenty of used/new filters on the internet. Which will give you a rough idea. As a filter gets used it turns black from all the stuff it collects. However a dark filter does not mean it's life is finished.
The AQI you see on the air purifier is a representation of the number of Airborne Particulate Matter (PM) that the laser in the back of the Air Purifier hit/detected. This can differ a little even between rooms for a number reasons, including airflow, ventilation, pollution sources, temperature differences, humidity, and air pressure.
Purifies the air in less than 10 min (1) With just one push of a button, the air purifier filters the invisible viruses, allergens or pollutants in your home to keep it clean and safe. It purifies quickly and effectively, thanks to its clean air delivery rate (CADR) of 300 m³/h. See all benefits.
xiaomi air purifier display meaning
