Editorial policy

Every site in this category says commercial relationships do not influence its recommendations. That is easy to say, so here is the actual mechanism:

Picks are selected against the published criteria before affiliate availability is checked. The ranking inputs — certified CADR, certified room size, certified annual energy use, measured ozone, filter classification — all come from public registers and are compiled before any link is built. A unit that ranks first ranks first whether or not there is a commission attached to it, and the criteria are written down on How We Pick where you can check our conclusions against them.

We also do not accept:

• Free products, review samples or loans
• Sponsored placements or paid inclusions in any roundup
• Payment to change, add or remove a ranking
• Guest posts or link insertions

Errors here are most likely to be one of three kinds: a figure misread from a register, a figure that has since changed, or a model that has been discontinued or re-rated.

• How to report one: the contact form, or info@danderdown.com. A link to the page and the figure you think is wrong is the fastest route.
• What happens: we check the claim against its cited source. If it is wrong we fix it.
• How quickly: factual errors about a product specification or a safety claim are treated as urgent. Everything else is handled in the normal review cycle.
• How it is marked: a correction that changes a recommendation or a material figure is noted on the page, with the date and what changed. We do not silently edit a claim and leave the page looking as though it always said the new thing.

Published so it is a commitment rather than an intention. This matters more than it sounds: while researching this site we found a major network-published roundup still ranking on a page last updated in July 2024.

Every numeric or factual claim on this site carries its source. In order of preference:

1. Standards bodies and regulators — AHAM, EPA, ENERGY STAR, the EIA.
2. Peer-reviewed literature, cited with authors, journal, year and pages.
3. Certification registers — AAFA / Allergy Standards.
4. Manufacturer published specifications — usable, and always attributed as manufacturer-claimed rather than restated as fact.
5. Manufacturer marketing copy — quoted and attributed if used at all, never restated as fact.

Standing prohibitions, which are absolute:

• No “studies show” without the study.
• No statistic without its source.
• No price, rating or review count written into copy. Prices render only from the live data layer, and show “Check price” when there is none.
• No unlabelled CADR figure. Every one is marked certified or manufacturer-claimed.
• If a number cannot be sourced, it does not appear. The page says what is known and what is not.

Several topics here touch a health condition. On those pages we do not make therapeutic or curative claims, we report regulators’ findings including their hedges rather than a stronger version of them, we state the source-control priority even though it argues against our commercial interest, and we carry a not-medical-advice statement recommending a clinician for persistent symptoms.

We do not diagnose. A page about morning allergy symptoms describes what the evidence says about airborne allergens; it does not tell you what you have.

Every page here is compiled from public registers and primary sources, and every figure is linked to where it came from. We would rather be checkable than merely confident, and that applies to how the content was produced as much as to what it says — which is why the sourcing standards above are published rather than implied.