The Xiaomi filters all have a filter performance of at least 99.9%. A few years ago, the air purifiers were sold with a standard blue filter, which was an EPA filter, but even that still had a filter performance of 99.97%.

The latest Generation 4 units also have grey filters, but these are designed for 6 to 12 months and have even better filter performance, they are also HEPA. But there are differences in HEPA filters, the grey HEPA filters are H13 while others are H11. (Purple and green are H11, so a little less good) So you can't go far wrong with Xiaomi filters. If you need a new filter now, you can take the grey HEPA H13 filters, which are the best in terms of filter reading.

The most important thing: don't just replace the filters when the app wants you to, they all last for years. Dust and hair, i.e. bigger stuff, is caught by the pre-filter, which is then simply cleaned of dust from time to time with the hoover and then reset the filter. In Switzerland, air pollution is not that bad, so the filters can be used for years. Clean air always comes out of the units :).

And it's also important to keep the units running all the time, because then dust doesn't collect at the top.

Different types of filters. Purple is Antibacterial. Grey is HEPA. Green is Formaldehyde. So to be considered depending on the application.