If you want to breathe cleaner, a smart air purifier can help. The Coway Airmega 250S ($449), for example, can remove dust, pollen, smoke, and other allergens from large rooms (up to 930 square feet). It also has Wi-Fi, allowing it to work with a thoughtfully designed mobile app and support voice controls. It doesn’t offer nearly as many features or provide as many air quality readings as some competitors, including our Editors’ Choice winner, the $549.99 Dyson Purifier Cool TP07. But it covers a much larger area than the competition for a similar price.
A Utilitarian Design
The Airmega 250S doesn’t look as modern as other smart air purifiers such as the Dyson Purifier Cool TP07 or the Sharp FXJ80UW Air Purifier. The bulky gray appliance measures 19.7 by 18.5 by 8.0 inches (HWD) and closely resembles old-fashioned box fans. It sports a large, off-white removable grille on the front and a textured panel along the bottom edge. Built-in handles on either side help you lug the 20-pound machine around your home.
A panel on the left side houses the pollution sensor. The 250S measures the PM 10 (coarse particles such as mold spores, dust, and pollen) and PM 2.5 (fine particles from tobacco smoke, cooking, and fireplaces) levels in your home, but doesn’t offer the more advanced VOC (volatile organic compounds), carbon dioxide, and carbon monoxide measurements that you get with similarly priced smart air purifiers such as the Aura Air.
The top of the cabinet is home to an LED strip that indicates the current air quality. The strip glows blue when the air quality is good (level 1), green when it is moderate (level 2), yellow when it is unhealthy (also level 2), and red when it is very unhealthy (level 3). The strip shares space with a power button; a light sensor; a Wi-Fi button; a button that turns all of the indicators and the LED strip on and off; a filter replacement indicator; a fan speed button with three settings (1-3); and a mode button that toggles between Smart, Rapid, and Sleep modes.
In Smart mode, the 250S automatically adjusts the fan speed according to the current air quality reading. Sleep mode keeps the fan at its lowest (and most quiet) speed unless the air quality hits the moderate level or it detects light for more than five minutes. Rapid mode uses the highest (and noisiest) fan speed for as long as necessary to maintain a level 1 air quality reading.
Two filters sit behind the removable front grille. One is a fine mesh prefilter designed to trap hair, dander, and large dust particles. The other is a MAX2 Green True HEPA carbon-activated filter that traps fine dust, bacteria, and other PM 2.5 particles, plus neutralizes odors, harmful gases, and VOCs. The two filters work together to capture 99.999% of particles that are as small as 0.01 microns. You can wash and reuse the prefilter, but you need to replace the MAX2 filter ($79 each) about once a year.
One of the more notable aspects of the 250S is that it works effectively in large rooms (up to 930 square feet, as mentioned). For comparison, the Aura Air and the Sharp FXJ80UW are respectively rated only for rooms up to 600 and 502 square feet. Dyson doesn't list an official coverage area.
App Experience
The Airmega 250S uses a 2.4GHz Wi-Fi radio to connect to your home network and the iOCare mobile app (available for Android and iOS). It also allows you to connect to Amazon Alexa and Google Assistant services to enable voice controls. You can, for example, use your voice to turn the purifier on and off; change the fan speeds and operating modes; turn off the LEDs; and set up sleep timers.
The iOCare app's home screen displays the current PM 2.5 and PM 10 levels by number and color (as mentioned above), and tells you the outdoor air quality in your area. Additional tabs sit at the top of the screen: Home, Report, Control, Notification, and Device Management. The Home tab takes you back to the home screen from anywhere in the app, while the Report tab lets you view graphs that display hourly, daily, weekly, and monthly indoor PM 2.5 and PM10 levels. The Control tab enables you to turn the purifier on and off; set a timer; change modes and fan speeds; and turn the LEDs on or off. Here, you can also create daily on and off schedules.
Tap the Notification tab to see the remaining filter life cycle and view any alerts. The Device Management tab also tells you how much time you have before you should wash the prefilter or replace the MAX2 filter; it includes a link to a purchase page for the filters on the Coway site. Here, you can also configure Wi-Fi settings; edit the device name and home location; and configure prefilter wash notifications.
Simple Setup, Solid Performance
To prepare the Airmega 250S for first use, I removed the front grille and both filters; removed the plastic wrap from the HEPA filter; and replaced both the filters and the grille cover. I powered up the purifier, downloaded the mobile app, and created an account. Next, I tapped the plus icon in the upper right corner of the welcome screen and used my phone’s camera to scan the QR code on the back of the purifier. I then pressed and held the Wi-Fi and Filter buttons for three seconds (per the on-screen instructions) and verified that the Wi-Fi LED was blinking before entering my network SSID and password. Setup is complete once the Airmega connects to the network.
The Airmega 250S did a great job of purifying the air in testing. I placed the appliance in my 110-square-foot office where I obtained a PM 2.5 reading of 1 and a PM 10 reading of 1 on the app. Next, I turned off the 250S, lit a stick of incense, and waited 10 minutes before powering up the device and setting it to Smart mode.
The purifier immediately displayed a PM 2.5 reading of 358 and a PM 10 reading of 367 and the LED strip turned to red. Three minutes later, the PM 2.5 level had dropped to 128 and the PM 10 level was at 126. At the six-minute mark, the PM 2.5 level was down to 29 and the PM 10 level was 31. After a full 10 minutes, the PM 2.5 level was at 6 and the PM 10 level was 7. It took a total of 12 minutes for the 250S to restore both the PM 2.5 and PM 10 levels to 1.
The purifier responded quickly to app commands in testing, and didn't have any trouble with Alexa voice commands to change the operating mode, set the fan speed, and turn the device off.
Lots of Coverage for the Price
Whether you suffer from allergies or simply want to keep your home free of pollen, dust, mold, and other harmful particles, the Coway Airmega 250S Air Purifier is worth a look. It’s not the prettiest air purifier we’ve tested, but it performed admirably in our air-scrubbing test and can cover much larger spaces than most competitors. We also like its mobile app and support for voice commands. If you want to monitor more than just PM 2.5 and PM 10 pollution levels, the similarly priced Aura Air is worth considering, while the Dyson Purifier Cool TP07 offers multiple pollutant level readings and doubles as an oscillating fan. But if you want to cover a larger space, the Airmega 250S should be high on your list.
