How to Choose an Air Purifier
2026-01-14
Air purifiers look similar on the outside, but the inside tells a different story. The filter type, fan power, and room coverage all change what the unit actually delivers. If you are buying for a desk, bedroom, or small apartment, the checklist is different from a whole-house system.
Step 1: Pick the Right Filter
HEPA is the baseline. True HEPA filters capture 99.97% of particles at 0.3 microns. That range covers pollen, dust, mold spores, and most smoke particles. Avoid anything labeled "HEPA-type" or "HEPA-like" — those are marketing terms, not standards.
If odors are a concern, add activated carbon. Carbon does not remove particles, but it adsorbs volatile organic compounds and smells. A good desk purifier often combines both.
Step 2: Match CADR to Room Size
Clean Air Delivery Rate, or CADR, tells you how much air a purifier can clean. For a desk or small bedroom, a CADR of 50 to 100 is usually enough. For a large open space, you will need 200 or more.
Step 3: Check Noise and Power
Sleep spaces need under 25 dB on low. Offices can tolerate 30 to 40 dB. Always check the wattage: a 30-watt unit running 24/7 costs less than $3 per month in electricity.
Step 4: Avoid Subscription Traps
Some brands charge a premium for proprietary filters and push subscriptions. That is fine if the performance justifies it, but many mid-range units use standard filters at half the cost. Always compare replacement filter price before buying.
Step 5: Verify Certifications
Look for CARB, UL, CE, and RoHS. These are not marketing badges — they are safety and emissions standards. A missing certification is a red flag for indoor air equipment.
The Bottom Line
Choose a HEPA-based unit sized for your actual room, check replacement costs, and verify certifications. That is the checklist that keeps you from buying a noisy box that looks good in photos.