Is a HEPA filter enough to choose an air purifier?
No. A filter specification does not by itself establish how quickly the whole unit supplies filtered air to your room. Compare CADR, the room assumptions and the relevant particle category, then check an operating setting you can use comfortably. [3]
AHAM’s CADR separates smoke, dust and pollen results. Use that information to frame a specific comparison instead of treating every “coverage” claim as equivalent. [3]
For a bedroom, ask whether published noise and clean-air delivery describe the same operating speed. Keep any missing speed-specific information visible in your decision. [1]
Read the full buying guide ↗Frequently asked questions
Is HEPA enough to choose an air purifier?
No. Compare the whole unit’s clean-air delivery and the intended room as well as its filter specification. AHAM’s CADR describes filtered-air delivery for specified particle categories. [3]
Can I use the maximum CADR figure for sleep mode?
Only if the manufacturer documents that relationship. Noise varies with operating speed. Without a speed-specific result, the maximum rating does not establish the delivery at the quietest setting. [1]
Sources & further reading
Original source pages checked 2026-11-05. Manufacturer statements describe the linked model or market; they are not independent performance tests.
- EPA: Guide to Air Cleaners in the Home ↗www.epa.gov
- AHAM: air filtration standards ↗ahamverifide.org