EPA chamber testing: DIY box-fan air cleaners removed wildfire-smoke particles at rates comparable to commercial purifiers
| Citation | Holder, A.L., Halliday, H.S., Virtaranta, L. — U.S. EPA Office of Research and Development chamber studies of DIY air cleaners (published in Aerosol and Air Quality Research), 2022 |
|---|---|
| Study type | Mechanistic study |
| Population | No human subjects — simulated wildfire smoke in a large controlled test chamber |
| Sample | Multiple DIY configurations (single-filter and Corsi-Rosenthal-style multi-filter builds) vs. commercial HEPA units |
| Primary source | https://www.epa.gov/air-research/research-diy-air-cleaners-reduce-wildfire-smoke-indoors |
Headline finding
Box-fan air cleaners built with MERV-13 filters produced clean-air delivery for smoke-sized particles comparable to commercial portable HEPA purifiers, at a fraction of the purchase price; multi-filter (CR box) designs outperformed single-filter designs, and fan-motor temperature testing found no fire-safety concern with filters attached.
Limitations
- Chamber study with simulated smoke — real homes have leakier rooms, furniture, and people opening doors.
- No health outcomes were measured; the endpoint is particle removal, not symptoms or disease.
- Performance depends on the specific fan and true MERV-13 filters; cheap unrated filters will underperform.
Why this evidence label
Controlled-chamber particle-removal data from a federal research program is strong for the engineering claim (DIY cleaners clean air effectively); it does not by itself establish health-outcome benefits in homes.
Editorial note
The practical upshot: during smoke events, a ~$70 build using a box fan and four MERV-13 furnace filters is not a gimmick — in controlled testing it cleans smoke-sized particles from air about as fast as commercial purifiers costing several times more. The trade-offs are noise, aesthetics, and doing the filter changes yourself.
Reviewed by Sonic Vitality Editorial on July 15, 2026 . See our methodology and corrections policy.