OUR METHOD

Show the working.

Filter Math is an independent reading room for air purifiers, air-quality monitors, and the costs of owning them.

Research, with its limits visible

The library contains 44 product dossiers and one monitor comparison. Eight guides and three dispatches help put the details in context. The product research snapshot is September 23, 2026.

We have not tested these products hands-on. The records collect manufacturer information, third-party measurements, price observations and attributed accounts. Evidence quality varies. UNVERIFIED means that a detail has not been confirmed; source presence alone does not make a claim reliable.

The air lab

The interactive diagrams explain concepts. The sizing calculator divides clean-air delivery by room volume. It does not simulate your room, predict health outcomes, or establish a safe exposure level. The cost calculator estimates a budget from numbers you supply.

Read the EPA guide to air cleaners in the home for guidance on choosing and using portable air cleaners.

Reading product research

Check current manufacturer documentation, model identity and independent certification records before relying on a product claim. Prices and specifications may have changed. Product imagery is reference material; uncertain identities and comparison-only images are labeled.

Independence

Rankings and verdicts are never for sale. See our funding policy.