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How we test air purifiers

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

how_we_test_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 volatile organic compounds (VOCs).

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 heating and cooling products, ranging from pedestal fans to split system air conditioners, portable air cons and ceiling fans.

Most CHOICE product reviews are conducted in our own labs, but when a test calls for skills or equipment that we don't have, and that aren't cost-effective for us to obtain, we partner with other expert, accredited labs. This is the case with our air purifier tests.

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're most likely to see in 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 to the retailers (online or in person) and purchase each product, just as a normal consumer would. We do this so we can be sure they're the same as any consumer would find them and not 'tweaked' in any way.

Sometimes there is limited available stock for particular products due to unusual conditions; this has sometimes been the case with air purifiers due to high demand in times of bushfire smoke and the COVID-19 pandemic. This means we can only include the models we're able to actually purchase at the time of testing.

How we test air purifiers

We test each air purifier with particles of dust, smoke and volatile organic compounds (VOCs) to measure how quickly and effectively it removes them from the air. This test is based on the Clean Air Delivery Rate (CADR) industry standard test for air purifiers. It's 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.

Each unit is tested on its highest fan speed setting to give it its best chance of performing well.

The pollutant (dust, smoke or VOC) is introduced in a controlled way into the test chamber and mixed into the air, then the testers measure how fast it naturally precipitates or decays from the air. Then the chamber is cleared and the test repeated, this time with the air purifier running. We calculate the percentage of particles removed by the air purifier and compare this with the natural decay rate measured earlier. This tells us how quickly and effectively the air purifier is clearing the air.

We test models on their highest and lowest settings so you'll know which ones are the least likely to disturb you

The best air purifiers will remove more than 90% of the particles used in our tests. The worst remove significantly fewer.

We test dust removal using fine particles of titanium dioxide. Smoke removal is tested by burning wood chips, and VOC removal is tested with acetone.

Pollen is a common indoor air pollutant and is a typical test for air purifiers, but unfortunately technical difficulties with pollen testing prevented us from measuring performance in this test. We intend to keep trying to find a way to include a pollen test in future. Meanwhile, any model which performs well in dust removal should also be good at removing pollen.

Since 1 in 10 air purifier owners we spoke to told us that their machine affected their sleep, we test models on their highest and lowest settings so you'll know which ones are the least likely to disturb you.

Test criteria explained

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

Performance: 70%

  • Dust, smoke and VOC removal, weighted 50/40/10, make up the Performance score.

Ease of use: 30%

  • Based on the model's onboard controls, its remote (if it has one), how easy it is to move around, whether it's prone to tip over, how easy it is to clean, and the quality of the supplied instruction manual. 
We care about accuracy. See something that's not quite right in this article? Let us know or read more about fact-checking at CHOICE.