If you suffer from allergies, have respiratory issues, or simply want to keep your indoor air pollution levels in check, the Airthings Renew can help. Designed for rooms up to 525 square feet, this smart air purifier supports app control and uses four-stage filtration to remove harmful pollutants. It performed well in testing and is relatively quiet, but we expect a few more features for its $399.99 price, such as onboard PM2.5 readings and voice control support. You get both with the $239.99 Dreo Macro Max S Air Purifier, which also costs less, making it a more attractive alternative.

Design: Minimal and Elegant

The Airthings Renew is a 16-by-16-by-5.7-inch (HWD) dark gray rectangular box with an air intake and filter assembly hidden behind a removable panel on the left side, an air outlet grill on top, and a power jack on the bottom. At 11.9 pounds, it is fairly easy to move from room to room and can be placed on the floor or hung on a wall using the included mounting bracket.

A control panel on top has very small backlit buttons for power/standby; Auto, Boost, and Sleep modes; and fan speed (1 to 5). In Auto mode, the fan speed will adjust based on the current air quality. In Boost mode, the purifier will run with the fan at its highest setting for one hour, and in Sleep mode, the fan will run at its lowest speed for eight hours. The control panel also has air quality, child lock, filter change, and Wi-Fi status indicator lights.

(Credit: John R. Delaney)

An embedded air quality sensor measures the concentration of PM2.5 (particulate matter 2.5 micrometers or less in diameter) but doesn’t capture any other data, such as CO2 (carbon dioxide), NO2 (formaldehyde), PM10 (particulate matter up to 10 microns in size, including dust, mold, and pollen), or VOCs (Volatile Organic Compounds).

The Renew's air quality indicator light shines green, yellow, or red based on the amount of PM2.5 in the air. Green means the air quality is good, yellow means fair, and red means poor. Missing is a built-in screen for numerical air quality readings like you get with the Dreo Macro Max S.

A side panel pulls out to reveal the Renew’s four-stage filtration system, which consists of a built-in textile pre-filter, a removable mesh pre-filter, a HEPA 13 filter, and an active charcoal filter. The textile filter can be cleaned with a vacuum, and the mesh filter is washable, but you’ll have to replace the HEPA and charcoal filters every six months or so. A two-pack (one HEPA and one charcoal filter) costs $69.99.

Like most HEPA-based air purifiers, the Renew removes 99.97% of harmful pollutants and has a CADR (clean air delivery rate) of 140 CFM (cubic feet per minute). It connects to your home network via a 2.4GHz Wi-Fi radio and can be controlled from anywhere using your phone, but it does not work with Alexa or Google voice commands, nor does it support Apple HomeKit or Matter. However, it supports IFTTT applets, allowing it to work with numerous third-party smart home devices such as cameras, light bulbs, and plugs.

The Airthings mobile app offers all of the same functionality as the onboard controls and more. It opens to a Devices screen with a panel for the air purifier. Tap the panel to open another panel that displays the current PM2.5 level. Tap the panel to view charts that show the PM2.5 levels for the last three hours, day, week, month, or year. Tap the Controls button on the purifier tab to launch a screen where you can change fan speeds, switch modes, apply the child lock, and turn the device on and off.

At the bottom of the Devices screen are buttons for Insights and Settings. The Insights button opens a screen to view five-day grass, tree, and weed pollen forecasts based on your location. These forecasts are color-coded green, yellow, or red like PM2.5 levels, and you get a brief description for each type of pollution, with warnings if the levels are high. Use the Settings button to edit your profile, select units of measurement, set data and privacy preferences, and configure other settings such as notifications and Wi-Fi. You can also head there to check your device's firmware version and filter life status.

(Credit: Airthings/PCMag)

Installation and Performance: Effective and Quiet

To prepare the Renew for first use, simply plug it in, download the mobile app, and create an account. Tap Add Device on the home screen and grant permission for the app to use Bluetooth, and it should immediately recognize the purifier and list it as a device. Select the purifier, give it a name, and tap Add Device to begin pairing. The app will then prompt you to press the purifier's Standby button for five seconds until the Wi-Fi LED flashes blue. Then, tap Continue, select your Wi-Fi SSID, enter your Wi-Fi password, and tap Done to complete the installation.

The Renew did a great job cleaning the air in my tests, but it’s not the fastest purifier I’ve tested. I placed the machine in my 110-square-foot office next to a Govee Air Quality Monitor, allowing me to see the actual PM2.5 levels during testing. The Govee displayed a PM2.5 level of 006, so I lit a stick of incense and waited 10 minutes before extinguishing the stick. When the Govee monitor read 200, I turned on the Renew and set it to Auto mode. The LED was red at this point, and the fan immediately kicked into high speed. After three minutes, the PM2.5 level dropped to 132; after six minutes, it read 80; and after 10 minutes, it had dropped to 42. After 20 minutes, the PM2.5 level was back to its original level of 006. By comparison, the Dreo Macro Max S needed 13 minutes to return to its starting point.

Using the NIOSH Sound Level Meter app, I recorded a noise level of 30dB with the Renew operating at the lowest fan setting and 60dB in Boost mode, which is reasonably quiet.

To test the Renew’s IFTTT capabilities, I created an applet to turn on an AIDot Linkind Bulb red when the purifier reported a particular PM2.5 level, and it worked without issue.

Verdict: Competent, But Pricey

The Airthings Renew Air Purifier does a good job of removing harmful pollutants from the air in rooms up to 525 square feet. It’s relatively quiet and works with plenty of third-party smart devices via IFTTT. Still, it lacks support for Alexa, Google, and HomeKit voice control, offers limited air quality measurements, and doesn’t display the actual PM2.5 level on the control panel. And at $399.99, it’s more expensive than similarly sized purifiers, such as the $239.99 Dreo Macro Max S, which also offers faster cleaning performance and voice control.