According to our test, you shouldn’t believe in the in-built particle counter for air quality indication, at least not in Mi2. Here’s what it promises to do—detect how bad air is in your home, so you know when to turn the purifier on when air is bad and turn it off when air is good. However, our test shows that even against modest expectations, the Xiaomi was off by a lot. When the air was bad, the Xiaomi was off by an astounding 218 micrograms.
Click here to read more on the original test: https://smartairfilters.com/en/blog/xiaomi-particle-counter-inaccurate-not-control-purifier/