What should I compare when buying an air purifier?
Compare filter running cost and replacement interval first, then air delivery. Air purifier specs and prices vary widely. Clarifion replacement filters cost $16.65 to $33.29 a year and need changing every 3 to 6 months, with units from $39.97. Vornado Air charges $39.99 a year for a change every 12 months, and rates 265.04 cubic meters of air per hour.