How to Buy an Air Purifier
An air filtration machine (which manufacturers often call a "purifier") may help remove irritants from the air. But not all models are that useful — or even healthy. What to consider — and avoid — when shopping.
What to Look For
CADR (clean air delivery rate) delineates the maximum square footage recommended in which to use the filter (a good baseline for choosing a room unit) and how quickly it can remove three types of pollutants: smoke (with a number ranging from 10 to 450), dust (10 to 400), and pollen (25 to 450). The higher the value, the faster — but not necessarily the more thoroughly — the machine filters the air.