Choosing which air purifier to buy can seem complicated. With thousands of air purifier models to choose from, how to choose? In this air purifier buying guide, we take you through the four steps on how to choose an air purifier.

What’s the Best Air Purifier?

The best air purifiers all share similarities in the technologies they use, which we share below. But the exact model that is best for you can depend on a variety of factors including the size of the space you are cleaning. With that said, let’s dive straight into the air purifier buying guide, with the four most important things to know when choosing an air purifier.

What to Look for in an Air Purifier?

Step 1: Ignore the Marketing Hype

Claims about proprietary technology aren’t backed up by the tests I’ve seen. The Molekule purifier is a good example of claims that don’t fit the data: Is Molekule really better than similarly priced air purifiers already on the market?

Also, ignore imported filters that try to convince you with European flags or beautiful blonde families living in all-white homes.

Step 2: Go Straight to the Numbers

Instead of marketing hype. Focus on the numbers. The most important numbers for an air purifier are the room size it covers (in sqft or m²) and its CADR rating.

Room size means how big a room the purifier can cover (when running on its highest setting). CADR tells you how much clean air is coming out of the purifier.

If you’re looking for a quieter air purifier, choose one with a higher room size/CADR number then run it on low.

Read More: What Size Air Purifier Do I Need?

Step 3: Know That More Expensive DOESN’T Mean Better

Don’t be fooled into thinking that more expensive purifiers are better. It seems logical; the phrase “you pay for what you get” exists for a reason, right? And who wouldn’t want to pay more to protect their health?

Unfortunately, the purifier world doesn’t work like that. Turns out air purifiers are surprisingly simple – they’re just fans and filters that can even be DIY-ed at home.

But most air purifier companies don’t want you to know that. That way they can charge thousands of dollars for clean air. Don’t take our word for it. Here’s data that shows two DIY air purifiers that cost just $30 performing as well as thousand-dollar machines.

Step 4: Find Third-Party Test Data

Once you’ve found an air purifier, find third-party data that backs up the claims. Some good resources:

AHAM Tests: The Association of Home Appliance Manufacturers (AHAM) has a searchable database of effectiveness tests that they ran (CADR).

Home Tests: Smart Air founder Thomas Talhelm has tested a handful of purifiers: Blue Air 203, IQ Air Health Pro Plus, Philips AC 4072, and DIYs. Test of Xiaomi here is important for anyone who owns Xiaomi.

Sweet Home Tests: The tests of this US citizen scientist include 7 major brands. His raw data is no longer up online, so I archived a copy of it here.

Shanghai Consumer Protection Bureau Tests: The Consumer Protection Bureau in Shanghai tested a huge slate of purifiers and published the results. They’re no longer online, so but I archived (and translated) the results.

Consumer Reports Tests: Consumer Reports has great tests of purifiers, but unfortunately the data is behind a paywall.

Step 5: Take a breath!

That wraps up the air purifier buying guide! To recap: when choosing an air purifier, don’t be fooled by marketing, but concentrate on the purifier’s data. Find third-party test data to verify a purifier’s effectiveness, and know that a more expensive one doesn’t necessarily mean more clean air.

How I Protect Myself

At home, I use the Smart Air Sqair HEPA air purifier.

Smart Air is a certified B Corp committed to combating the myths big companies use to inflate the price of clean air.

For a fraction of the cost, Smart Air provides empirically backed, no-nonsense purifiers and masks, that remove the same particles as the big companies. Only corporations benefit when clean air is a luxury.

Interested? Check out the Sqair.