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.
HEPA, the same type of filter that traps dust within vacuum cleaners. In a room air filter, HEPA can capture very small airborne particles before they settle.
“Asthma and Allergy Friendly,” a relatively new certification from the Asthma and Allergy Foundation. Only a few units have earned it so far, by proving that they reduce (and don’t just redistribute) allergens.
What to Skip
Ozone: Some machines, which may be marketed as air fresheners, generate ozone for its sweet-smelling fragrance. Don’t buy these: Ozone is a known lung irritant.