Air purifiers: fans, sensors and the real cost of filters, from people who have run them for a year.

Three across two brands, from 32 owner accounts. Beta: fewer accounts, subjects still settling. 3 of them thin, under 40 accounts.

• Levoit Vital 200s→15accounts

  Owners who raised each subject are split so far.

• Levoit 600s→9accounts

  Owners who raised each subject are split so far.

• Coway Airmega 400→8accounts

  8 owner accounts, but no single subject raised by 4 or more of them yet (the most so far: 2).

Order: how many owner accounts we read, most first. Nothing else moves a product up or down.