How to Choose an Air Purifier: A Buyer's Guide

With wildfire smoke seasons, allergies and more time spent indoors, air purifiers have become a common household purchase. But with hundreds of models on the market, how do you choose? Here's what actually matters.

1. Look for a true HEPA filter

A true HEPA filter is designed to capture at least 99.97% of particles 0.3 microns in size, which covers dust, pollen, pet dander and much of the fine particulate in smoke. Be wary of vague terms like "HEPA-type" or "HEPA-like."

2. Check the CADR rating

CADR (Clean Air Delivery Rate) tells you how quickly a purifier cleans the air. Higher is better. A common rule of thumb is to choose a CADR of at least two-thirds of your room's square footage.

3. Match it to your room size

An undersized purifier in a large room won't do much. Check the manufacturer's recommended room size, and size up if you have high ceilings or want faster cleaning.

4. Consider noise

If it's going in your bedroom, look for low decibel ratings on the lower settings. A purifier you turn off because it's too loud isn't helping.

5. Factor in filter costs

Replacement filters can cost more than the machine over time. Check how often filters need changing and what they cost before you buy.

Features to skip

• Ozone generators — ozone can irritate the lungs. Avoid purifiers that intentionally produce it.
• Ionizers — some produce small amounts of ozone; check certifications.

Where to put it

Start with the bedroom, where you spend the most uninterrupted time. Keep doors and windows closed while it runs for best results.

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