In China the air filtration is actually used very common by middle class because of the air pollution. Many new furnished home would install the centralized air

In China the air filtration is actually used very common by middle class because of the air pollution. Many new furnished home would install the centralized air filtration along with AC (for heat exchange purpose) And usually it costs about 5-20k us dollars (depending on number of rooms and size). I don't think this price level is only for rich. Note that many vendors are actually Japanese brands such as Panasonic, Daikin.