How we research and rate air purifiers and monitors

Some older pages on this site say products were tested in person. That wording is wrong, and we are correcting it page by page. This page describes what we actually do.

Where our information comes from

• Manufacturer specifications. CADR for smoke, dust and pollen, rated coverage area, noise in decibels at each fan speed, power draw, filter type, filter life and replacement filter price. We take these from the manufacturer's product page, manual or spec sheet.
• AHAM Verifide CADR. AHAM certifies CADR under the ANSI/AHAM AC-1 standard and publishes a directory of certified models. When a model is in that directory, we use the certified figure. When it isn't, the CADR is the manufacturer's own claim, and we treat it as one.
• CARB certification. The California Air Resources Board certifies that an air cleaner emits no more than 0.050 ppm of ozone. It matters most for purifiers with an ionizer, UV lamp or other electrical cleaning stage, because those are the ones that can produce ozone, and we say when a model is certified.
• Energy Star. Energy Star certifies room air cleaners on CADR per watt. Where a model is certified, we say so, and we use its listed power draw for running cost estimates.
• Air quality monitors. We use the manufacturer's stated sensor type, measuring range and accuracy, and independent evaluations where one has been published.
• Health and air quality science. For PM2.5, VOCs, CO2, radon and allergens we cite the EPA, the WHO, other public health agencies and peer-reviewed studies, and link to the primary source so you can check it.
• Prices. Amazon prices come from the Amazon Creators API, Amazon's catalogue feed for Associates. A price is accurate only as of the date shown next to it and is subject to change. The price on Amazon at checkout is the one that applies. Every price we show carries the date we last checked it, and the price disclaimer explains the rest. If you find a price without a date, treat it as approximate.

Our scores don't draw on customer star ratings or review counts from any retailer, and we don't show them on our pages.

What we calculate

Some figures on our pages are our own arithmetic from published specs. Examples are the room size a purifier can clean at a given number of air changes per hour, CADR per dollar, and running cost per year from filter prices and power draw. The CADR calculator shows the formula we use. These are calculations, not measurements, and they are only as accurate as the specs they start from.

What our scores mean

Each product has a score out of 10 and four sub-scores: performance, noise, value and features. These are editorial scores. They are not test results, and they are not customer ratings.

• Performance reflects CADR (certified where available), rated coverage and filter type. For monitors, it reflects which pollutants the device senses and its stated accuracy.
• Noise reflects the manufacturer's published decibel figures, especially at the speeds you would actually run it on.
• Value reflects the price and the yearly filter cost against what the product delivers on paper.
• Features reflects things like auto mode, air quality sensors, app control and filter-life indicators.

Our editors assign the scores after comparing a product with others in the same category. The overall score is a judgment across the four, not a fixed formula, so treat a gap of a few tenths as close to a tie. A score can't tell you how a product will perform in your room. The written recommendation, and who each pick is best for, matter more than the number.

How pages are written, reviewed and updated

• Pages are researched and written by the CleanAirCritic editorial team.
• Before a page is published, its product specs are checked against the manufacturer's source. Automated checks run before every site update to catch broken links, missing images and faulty structured data.
• We revise pages when a manufacturer changes a spec, discontinues a model or releases a replacement, and when prices move. Each page shows the date it was last updated.
• When an affiliate link stops working or a product is no longer sold, we repoint or remove it.

How our affiliate links work

Most product links go to Amazon and carry our Associates tag. A few go to the manufacturer's own store, and some of those are affiliate links too. If you buy through one, we may earn a commission at no extra cost to you. That is how this site is funded.

A commission doesn't change a score or a ranking, and no manufacturer pays to be included. If the right product for a situation comes from a brand with no affiliate program, we still recommend it. Read our full affiliate disclosure.

Found an error?

We want to know about any spec, price or claim on this site that doesn't match its source. We don't have a public reader inbox yet, and we would rather say so than list an address nobody reads. When one is set up, it will be posted here.

What we don't do

• We don't measure CADR, noise, ozone output, energy use or sensor accuracy ourselves.
• We don't run products for weeks to judge filter life or durability.
• We don't accept payment for coverage or placement.

Read more about CleanAirCritic, or see what CADR means in our CADR explainer before you compare purifiers in our buyer's guides.