A great air purifier can really improve your life. But to qualify as great, it needs to be powerful enough to clean the air in a large living
room or playroom, quiet and dark enough for you to sleep near it in a bedroom, and inexpensive enough that it’s reasonable to have several
spread throughout your home.
Few machines meet that standard, but after seven years of testing 35 different air purifiers.
Best overall: Blueair Blue Pure 211+ Air Purifier.
Best on a budget: Honeywell HPA300 True HEPA Air Purifier.
Best wall-mounted purifier: RabbitAir MinusA2 Ultra Quiet HEPA Air Purifier.
Best splurge: Coway Airmega 400 Smart Air Purifier
This also goes for the top of the air purifier. By placing it under a shelf, the only thing that’s going to get that fresh air is the underside of your book shelf.
The rule of thumb is to keep a few feet of clearance at the top, front, and sides for optimal efficiency.