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How we test air purifiers

Dust, smoke and pollen help us find the the best air purifiers.


Air purifiers are basically fans with filters inside. Air is sucked in and passed through the filters to capture any particles floating in it. Our testers put them in a sealed test room to measure how well they clean the air of dust, smoke and pollen.

Our expert testers

We've only been testing air purifiers for a short period now, but our expert testers know what makes a good one. Our experts also have 20+ years of experience in heat and cooling products, ranging from pedestal fans, to split system air conditioners, portable air cons and ceiling fans.

How we choose what we test

With so many to choose from, what makes us choose one air purifier to test over another? As with most of our product testing, our aim is to test the most popular brands and types on the market, and what you are most likely to see in the shops.

  • We survey manufacturers to find out about their range of products.
  • We check market sales information.
  • We check for any member requests to test specific air purifiers.

From this information we put together a final list that goes to our buyers. They then head out to the retailers and purchase each product, just as a normal consumer would. We do this so we can be sure they are the same as any consumer would find them and not 'tweaked' in any way.

How we test

How well does each air purifier remove allergens, such as dust, smoke and pollen from the air?

We test each air purifier with particles of pollen, smoke and dust to measure the clean air delivery rate (CADR) of each machine. This measures the reduction of particles in the air. CADR is an industry standard test for air purifiers and is a good way to compare models, but be aware that performance in your home might be different, due to different room sizes and shapes and varying levels of pollutants.

We calculate the percentage of particles removed by the machines and compare this with the particles that are naturally removed from the air with the machines switched off. The best air purifiers will remove more than 90% of the particles used in our tests. The worst remove significantly fewer.

How noisy is the air purifier on full and low power?

One in ten air purifier owners we spoke to told us that their machine affected their sleep. So, we test models on their highest and lowest settings so you'll know which ones are the least likely to disturb you. We measure the sound levels and use an expert panel to listen out for irritating noises.

Are air purifier filters easy to remove and replace? 

We remove and replace the filters on all of the air purifiers we test to see which ones are easy to pop out, and which are a struggle to remove. 

If the air purifier comes with a smart app, how easy is it to use? 

We check how easy it is to connect the smart app to the air purifier and then set the machine from the app. We check whether all of the functionality of the purifier is available through the app and assess how easy the app is to use.

Test criteria explained

We weight each of our criteria a little differently based on the consumer need.

Performance: 70%

  • Smoke, dust and pollen removal, equally weighted, make up 80% of the Performance score.
  • The remainder is made up of the Noise rating and Energy rating at 10% each.

Ease of use: 30%

  • Controls 50%
  • Changing the filter 25%
  • The indicators on the product 25%

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