what air purifier you all buy?   i read that xiaomi most common, some other get locally like honeywell, sharp etc...   as usual seek a proved HEPA air filter and also where do you get your filter from? TB air filter proved to work? i saw many 3rd party air filter?     there also this Daikin Streamer Air Purifier it claim no need to replace any filter. as quote " Collect dust more efficiently as a larger amount of air can pass through the filter and greater savings as the filter can last for 10 years in operation."

PAP need to do something. Go overseas visit here and there but never learn a few things.    I hear money is spent to build some kind of buzzer in the home. Dont waste money. It will not work   Have some kind of social pairings of old people in the block. Offer regular tea parties to engage these single old folks   If you dont like this idea because it did not come from your cronies then suggest something. Dont do the throw money at some tech thing. These old people are not for it

@The_King