Coway Airmega 350 air purifier review: powerhouse air purification for larger rooms

Welcome to T3’s review of the Coway Airmega 350, a powerful and very efficient air purifier for larger rooms and open-plan environments.

If you’re in the market for a best air purifier that’s capable of servicing rooms up to 185.5m², the high-performance Coway Airmega 350 is a top contender that comes highly recommended.

I’ve been testing this model for the past week and I’ve been very impressed by how well it has responded to pollutants in the air and how efficiently it’s cleared a large living room of incense smoke. It’s also one of the quietest models I’ve tested to date. Here’s my review of the Coway Airmega 350.

Coway Airmega 350 review: Price and availability

If you live in the UK, you an purchase the Coway Airmega 350 direct from Conway for a discounted price of £264.99 or visit Amazon where it’s selling for an RRP of £299.99.

Living in the US? Head straight to the Coway website where the Airmega 350 is shifting for $267. Alternatively, try Amazon, where it’s selling for the same price.

Coway Airmega 350 review: Design and features

I’ll admit that I haven’t reviewed anything by the South Korean Coway brand in the past, but on evidence of this cracking large-room air purifier's performance, quite a few plaudits from professional reviews and, to top it all, a Red Dot Award in 2025 for innovation, I’m happy to welcome the brand into my home.

At first, I thought the Airmega 350 might be just another bandwagon-eqsue model in a sea of air purifiers. But I was wrong because the Airmega 350 is turning out to be one of the best air purifiers for large rooms I’ve so far come across.

At 59.1cm in height and a rotund 30.5cm in diameter, the cylindrical Airmega 350 is bigger than other models I've reviewed though, in its favour, it is designed for larger rooms up to 185.5m² (that’s a room that measures 13.62m in length and width).

While large in stature, I have to say I’m quite taken by its clean white lines, hidden filter door and attractive white, translucent, top-mounted interface. According to the Coway website, this interface should remain dust free and I’m inclined to agree because I have the dustiest house in Oxfordshire and I’m impressed by how little dust has settled on it during the past five days.

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The interface itself sports a range of operational and informational functions. Starting on the left, the Mode setting provides four different fan speeds: Auto, Sleep, Turbo and Eco. Auto is just what it says and makes full use of the unit’s excellent – and very sensitive – sensor, ramping up the fan speed when excessive amounts of pollutants are detected. When this happens, the circular light around the interface glows in several different colours – blue in rest mode, green when something is detected, yellow when the air’s a bit iffy and red when the sensor detects major levels of pollutants like smoke from a cigarette or wood burner.

Sleep mode, meanwhile, lowers the fan speed at all times making it almost inaudible, even from a few feet away; Eco, too, is relatively quiet while Turbo – the most powerful setting – is, of course, on the loudest end of the scale but not as ear-piercing as you might imagine because, overall, this is one of the quietest air purifiers I’ve ever tested. The final three functions include fan speed (three settings), a lights on/off button, a timer (1, 4 and 8 hours) and an info reminder when the filter needs replacing.

So what’s the baby elephant in the room? Well, sad to say, but this particular model does not have WiFi capability and that means that it cannot be controlled using your phone. Although it’s not the end of the world, I do consider the lack of any app connectivity a missed opportunity, especially given that some other models in the Coway range can be used with a phone.

From an inconvenience point of view, it means that you can’t remotely view any air-cleaning stats, make any adjustments to the modes and fan speeds and, perhaps most concerning of all, turn it off using your phone should you suddenly remember that you left the Airmega 350 running while you’re at the airport getting ready for a three week holiday.

Given the size of this unit, it shouldn’t be surprising that the filter itself is a whopping 31cm x 26cm. Moreover, I reckon it should take Best Filter Colour of the Year award for its gorgeous dark iridescent green. Shame you’ll only ever see it when first unboxing and when replacing it a year or so later.

On a serious note, the Airmega 350’s filter looks exceedingly well designed and with a level of build quality you normally only seen in a Dyson, Phillips or Blueair. The 3-stage filter itself is of the HEPA variety with built-in pre-filter and Activated Carbon Filter for capturing the prerequisite 99.99% of airborne pollutants, including dust and odours. According to the stats, the Airmega 350 delivers a CADR (Clean Air Delivery Rate) of 713.6 m³/h. This figure is considered very good by people in the know and indicates that the Airmega 350 is powerful enough for large rooms, open-plan living spaces and even small offices.

Of course, one of the biggest issues when buying an air purifier from anyone other than the main players like Phillips, Blueair or Dyson is the availability of air filters, especially a year or so after purchasing the unit. I have reviewed a few smaller brands’ wares in the past and noticed that their filters were no longer available, either because of sold-out stock, the company no longer supporting that particular product or the company going into liquidation.

In this instance, it’s reassuring to note that Coway has an established base in the UK, operating as part of its European expansion with a dedicated Coway UK website and decent presence on Amazon. For the record, a new Airmega 350 filter at Amazon retails at a reasonable £69.99. I should also add that, as of writing, the Airmega 350 filter isn’t currently available on Coway’s UK website though I've been told that it very soon will be.

Coway Airmega 350 review: Performance

The first thing that strikes you when turning this thing on is just how quiet it is when it’s just ticking over. Granted, the noise ramps up considerably when the sensor detects high levels of pollutants but this subsides once the air is cleaned, usually in just a few minutes.

Crucially, the sound the fan makes is low frequency – like the MeacoFan 1056 – so you don’t have to endure a shrill harmonic hiss that invariably collides with some of the higher frequencies from an average television. That means you can continue watching “The Night Manager” with minimal background noise like I did.

I’ve tested this unit using a fragrant Palo Santo incense stick and have been extremely impressed. Firstly, the Airmega 350’s sensor is very sensitive so it doesn’t take much to kick it into gear. If there’s only a marginal amount of pollutants around it, it will generally run at half speed. But once the sensor detects anything like cigarette or wood burner smoke in the vicinity, the top circular lamp starts glowing bright red and the fan changes to top gear, where it stays like that for a minute or two before easing back once the air’s been cleaned.

This model also has excellent suction power and I noticed this when it started to draw in the incense smoke from about four feet away. When I positioned the unit in a central position in my living room with a lot of incense smoke wafting about, it look less than a minute for the sensor to detect it and about another eight minutes for the filter to fully clear the air.

I also performed a scent test – using both cigarette and incense smoke – with my face directly above the upward-facing outlet. I wanted to see if I could smell any remaining odour from their smoke. The cigarette test was 100% successful with no smell of tobacco smoke at all but, as I expected given the intense aroma of Palo Santo wood smoke, I could detect a faint hint of its wonderful fragrance.

To conclude, I’ve been exceedingly impressed with this unit. It’s easily powerful enough for large rooms, it’s quieter than others I’ve tested and it’s extraordinarily effective, too. Just wish it came with the convenience of WiFi connectivity.

Coway Airmega 350 review: Verdict

With its huge HEPA and carbon filtration system and very responsive sensor, the Coway Airmega 350 delivers powerful and reliable air purification for large rooms. It’s really quiet during everyday use and it reacts swiftly to odours and allergens, making it ideal for allergy sufferers, pet owners and smokers. While its lack of WiFi connectivity and current filter costs limit its value a smidgen, this is a dependable, high-performance purifier that genuinely impresses.