Walk into any store selling air purifiers and you'll see the word "HEPA" everywhere. But not all HEPA filters are the same, and the distinction matters significantly for your health.
What HEPA Means
HEPA stands for High-Efficiency Particulate Air. The term was originally developed by the US military during the Manhattan Project to filter radioactive particles. A true HEPA filter must capture at least 99.97% of particles that are 0.3 microns in diameter — the most penetrating particle size (MPPS).
True HEPA vs. "HEPA-Type" Filters
True HEPA: Meets the official standard — captures 99.97%+ of particles at 0.3 microns. This is what you want. Look for the exact phrase "True HEPA" or "H13 HEPA" on the packaging.
HEPA-Type or HEPA-Like: Marketing terms with no regulatory meaning. These filters may only capture 85–99% of particles, which sounds good but means significantly more pollution gets through — especially at the smallest, most dangerous particle sizes.
H13 HEPA: A European standard that captures 99.95% of particles at 0.3 microns — essentially the same as True HEPA and often used interchangeably.
H14 HEPA: Even stricter — 99.995% efficiency. Used in hospitals and cleanrooms. Overkill for most homes but impressive if you need it.
Do HEPA Filters Remove PM2.5?
Yes — True HEPA filters are highly effective against PM2.5 (particles ≤2.5 microns). They also capture pollen, dust mites, mold spores, most bacteria, and some viruses.
What HEPA filters don't remove: gases, odors, VOCs, and chemicals. For those, you need an activated carbon filter in addition to HEPA.
How to Buy the Right Filter
- Look for "True HEPA" explicitly — not "HEPA-type," "HEPA-like," or "99% HEPA"
- Check for activated carbon if odors or gases are a concern
- Verify the filter matches your model — generic filters may not seal properly
- Replace on schedule — HEPA filters lose effectiveness when clogged. Most manufacturers recommend every 6–12 months
Our Recommendations
All air purifiers we recommend on LocalAirData use True HEPA filtration. Browse our top picks in the air purifier guide.