We recommend air purifiers with a CHOICE Expert Rating of 70% or more.

This is made up of performance (70%) and ease of use (30%).

Based on dust removal (50%), smoke removal (40%) and VOC removal (10%).

How well this model filters out dust compared to the other models on test.

How well this model filters out smoke compared to the other models on test.

How well this model filters out volatile organic compounds (VOCs) compared to the other models on test.

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.

How the model compares for its energy efficiency (energy used in the dust performance test) against the other tested models. Air purifiers don't use a lot of power, but the best models combine low energy consumption with good dust removal performance.

The noise measured on the highest speed setting.

The noise measured on the lowest speed setting.

Shop Ethical rates the environmental and social impact of the company (not the product) using independent sources. This rating is not included in our total score. N/A means there is no rating for that company.

How often the HEPA, charcoal and other special filters should be cleaned or replaced. Some models simply give a recommended time period, others will alert you, and some may do both.

Stated warranty of the product. You're still covered by the Australian Consumer Law regardless of the manufacturer warranty.

The claim of where the product was put together.

'Tested model' refers to air purifiers that are currently available in shops and online. 'Discontinued model' refers to air purifiers that are no longer available in shops, but may be available second-hand.

Typical retail price at time of publication.

The cost of replacement filters: HEPA, pre-filter and carbon filters as appropriate for each model. Some models have an all-in-one filter that combines all these types and must be replaced entirely each time. N/A = not available (we couldn't find any replacement filters or pricing; note the Hitachi claims 10-year life for its filter.)

Estimated cost per year for replacing the filters, based on the manufacturer recommendation and assuming the best case for how long the filter is claimed to last. Some filters will need to be changed more than once a year, other filters will last longer.

The number of fan speed settings, including special modes such as night, heating and automatic.

The claimed room size (usually a maximum) for which the air purifier can keep the air clean. Treat this as a guide rather than a rule.

Rounded to the nearest cm.

High Efficiency Particulate Air (HEPA) – capable of trapping extremely small particles of dust, smoke and even bacteria and viruses. These filters need to be periodically replaced.

A coarse filter to catch big dust particles and pet hair so that they don't clog the HEPA and other filters. These can usually be washed and reused but may need to be replaced eventually.

Charcoal or carbon filters are said to be good for trapping odours and VOCs such as formaldehyde. These can usually be washed and reused but may need to be replaced eventually.

Generates charged particles (ions) to remove pollutant particles and microbes from the air. These filters need to be periodically replaced. Ionisation of air can produce small amounts of ozone which is a breathing irritant.

UV light can be used to kill bacteria and viruses trapped by the purifier. We haven't tested this feature.

Some models use ozone to remove dust and other particles form the air. Excessive ozone can be a breathing irritant and we generally recommend avoiding these models, but include them in the test to see how they perform.

Does the device have a remote.

Some models can be controlled via an app on your smartphone. The app may also show data about the amount of pollutants detected and removed.

Most models have various timer settings to run for a set number of hours. Timers might apply only to certain modes such as Night or Away (for use when you're away from the home).

The model's claimed dust removal rate as per industry-standard Clean Air Delivery Rate (CADR) tests. This shows how cubic metres per hour the model claims to process.

The claimed percentage of microbe removal, or other related claims. We haven't tested this aspect of performance.