How we test air purifiers

Unlike most consumer products, the work an air purifier does is hidden from the naked eye. 

You could think that an air purifier has cleaned the air in your bedroom, but unless you have a high-quality laser sensor, you could still be breathing in harmful tiny particles.

It would be great if you could trust manufacturer claims, but sadly manufacturers want you to buy and will say what they need to say to make it so.

That is why HouseFresh exists.

Objective performance testing

We use incense smoke and an optical particle counter sensor to track how fast air purifiers clean the air in our test room.

Since 2021, we have been testing the air cleaning power of air purifiers with our trusted air quality Touch sensor from PurpleAir, which uses the PMS1003 laser counter. 

We built our own tool to connect to the PurpleAir API, so we can pull regular readings of PM1.0, PM2.5, and PM10.0 particle levels in our 728 cubic ft. test room while we are running a test, which allows us to produce performance graphs like this:

Since 2024, we have upgraded to a more effective sensor from PurpleAir Zen, which utilizes PurpleAir’s PA-II and has two PMS6003 optical particle counter sensors for improved accuracy. Smart Air recently confirmed the PA-II to be the most accurate sensor in a study that compared accuracy across 55 different sensors. 

In addition to upgrading the sensor, we also moved to filming the air cleaning performance test, making sure to include the creation of the graph in real-time. 

Comprehensive sound testing

We use a sound level monitor to measure the decibels of noise the air purifiers generate when running at each fan speed.

While air cleaning performance is the most important feature of an air purifier, we also consider sound levels generated because we know that noisy devices are likely to gather dust in a corner without being used regularly.

Many air purifier manufacturers include sound in decibels when running the device at the highest fan speed based on their own tests. Unfortunately, we have found that some brands will understate these figures, so we know it’s important to gather our own data.

We use our trusted sound level monitor to record noise levels in decibels generated by the air purifier when running at every fan speed from 3 ft. away.

As with our air cleaning performance test, each device is tested for sound in the same location and using the same tools, so results can be compared across different brands and models.

Since 2024, we have moved to film this test so readers can see how much sound is generated. 

Accurate energy consumption testing

We use our energy meter to record how much electricity the air purifiers consume in watts when running at each fan speed.

Air purifiers generally need to be left running 24/7, especially when dealing with issues such as allergies or outdoor air pollution. However, some of these devices have power-hungry motors and fans that can result in hefty energy bills.

That is why we test each device with an energy meter to measure how much wattage is pulled at each fan speed, including sleep mode and standby functions.

Similarly to our other tests, since 2024, we have started filming this test so readers can see how much electricity is pulled. 

Associated long-term costs

We calculate how much money you will spend replacing HEPA and activated carbon filters across 12 months.

Another cost that consumers buying an air purifier for the first time might not be fully aware of is the cost of replacing filters. Small air purifiers might require two filter changes per year, and since filters range from $50 to $100 per filter, the costs can add up quickly.

That is why we always calculate filter replacement costs for every air purifier we review, sharing both genuine and generic filter prices.

Once we have the latest filter price data and the added costs to your energy bill, we can estimate yearly running costs so this information can easily be compared across devices.

Quality-of-life features and materials

We use the air purifiers in our home, putting all the features to the test in real-life scenarios.

If you have never used an air purifier before, you are likely unaware of the many features that can benefit you in the long term.

By using these devices in our homes, we can test out auto-modes in real time, use their smartphone apps from our phones, run them at night with sleep mode on and test how easy each device is to clean and maintain. This allows us to write comprehensive reviews of what it’s like to live with these air purifiers day in and day out. It also gives us enough time to uncover faults and issues that won’t show up during a simple photoshoot of the unit.

But we don’t stop there. We are happy to open the air purifier to explore its internals when something doesn’t sit right. 

This is how we can identify the different parts and materials being used, highlighting issues that you won’t see when looking at the air purifier from the outside. Just to show you how powerful this step of the review can be, this is how we uncovered that the PuroAir HEPA 14 240 is just a cheap clone of the Levoit Core 300.

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Assessing the value of a device with comparable data

We use our first-hand data and long-term experience with every unit we have ever tested to decide whether a device will be good value for your money.

Since the start of the COVID-19 pandemic, the air purifier industry has been flooded by overpriced devices sold to unsuspecting customers with clever marketing tactics.

Consumers today are being duped into buying useless gimmicks with the help of untested claims and even outright lies, massively overpaying for what is basically just a fan and a filter. 

By using a repeatable, comparable approach to testing, we hope to let the data guide more people away from these overhyped devices and toward those that effectively clean the air for a fair price and without excessive noise or energy usage.

We also understand that not everyone has hundreds of dollars to spend on an air purifier, so we are always on the lookout for devices that cost less but still perform well, including DIY options like the CR Box.