Problem Explanation：
1. Mi Air Purifier adopts 360-degree annular filter core and three-layer filter screen structure.Among them, the innermost layer of the coconut shell activated carbon filter is the use of "Kuraray" (Kuraray, founded in 1926, is the world's famous polymer chemistry, innovative material technology manufacturer) the production of high-quality dedicated activated carbon, can effectively adsorb formaldehyde and other harmful gases.Its activated carbon particle formula itself will have a very slight acid smell, but is completely harmless to human body, can be safely used;
2. In addition, in some extreme environments, such as severely polluted confined Spaces (such as newly decorated houses), a large amount of harmful gases such as formaldehyde adsorbed by the filter element will be blown out by the circulating airflow of the purifier for a period of time, resulting in a certain sour taste.
3. At this point, put the activated carbon part of the filter element (the annular filter in the middle) in a place with sufficient sunlight and good ventilation for a period of time, which can effectively solve the problem.If the filter element is used for a long time (3-6 months), it is recommended to directly replace the new filter element.