Guides

'Tested to NSF standards' describes a one-time lab result a brand controls, while 'NSF certified' is an ongoing third-party program you can verify in a public database.

The word HEPA on a box can mean a tested 99.97 percent filter or nothing at all. Here is how to read the label, what H13 and H14 add, and why a sealed air path matters as much as the filter itself.

CADR is the one number that tells you how fast a purifier actually cleans air, and it is also the number marketing departments stretch. Here is what it measures, how to match it to your room, and why the coverage area on the box is usually optimistic.

Wildfire smoke is mostly fine PM2.5, with gases mixed in. Choosing well comes down to enough clean-air delivery for your room, a sealed HEPA filter, activated carbon for odors, and avoiding devices that add ozone.

A FilterScored editorial on methodology. Expensive, well-regarded units sometimes score below a Coway or Levoit. The reasons are consistent: we credit AHAM-verified CADR, weight total cost of ownership, and flag overstated room-size claims.

PFAS are a large group of synthetic chemicals; in 2024 the EPA set enforceable drinking-water limits of 4 parts per trillion for PFOA and PFOS, and specific filter certifications confirm reduction.

Five common filter formats, side by side: what each one actually removes, what it costs per gallon, how hard it is to install, and how to match the format to your real problem instead of buying on vibes.

Your water utility mails you a Consumer Confidence Report every year, and most people throw it out. Here is how to find it, decode the jargon, spot a number near a limit, and turn a finding into the right filter certification.