This smart air purifier detects bad air in my home and switches on automatically

  • A good air purifier should filter out allergens while running silently.
  • That the Coway Airmega 400 Smart Air Purifier adjusts its fan speed based on pollution levels is great.
  • On the lowest setting, it is scarcely audible. Plus, it looks nice in my dining room.

This smart air purifier detects bad air in my home and switches on automatically

Coway Airmega 400 Smart Air Purifier

Pros: Quiet operation, 15-minute air purification, energy efficient, appealing design.
Cons: Inexpensive replacement filters that don’t remove VOCs.

You should seek for ways to improve indoor air quality if your home is full of smoke, dust, pollen, pet hair, and other waste. In addition to frequently sweeping and cleaning your HVAC filters, a good air purifier can assist you out.

I’ve been using the Coway Airmega 400 Smart Air Purifier, a new model from one of the industry’s top companies.

CAD and spec

Available in white and graphite/silver. I tried the graphite variant, which matched my dining room’s darker tones. The device is 23 inches high and 15 inches broad and deep, so it doesn’t take up much area.

The 25-pound unit isn’t great for moving around the house to filter the air. If you want to move it, it has handles on both sides.

Airmega 400S Banner

Here are some more vital specs:

  • Coverage: 24,960 cfh. It can clean the air in a 28′ x 28′ room with an 8′ ceiling four times in an hour.
  • Filters: Washable prefilter and Max2 filter set with True HEPA and activated carbon.
  • 120V 60Hz rated voltage
  • Energy Star certified at 66 W.
  • You can set the timer for one, four, or eight hours.


The Airmega 400 was a breeze to set up. I took the purifier out of the box, plugged it in, and it started working. It took roughly 15 minutes total.

Before turning on the Airmega, remove all plastic from the two Max2 filters on either side. This little task let me get to know the equipment. The directions are in the user handbook.

When you initially turn on the unit, it automatically switches to Smart Mode, which I’ll explain later. You may change the mode by running your finger along the touch sensor. In Smart Mode, usually.

What sets apart the air purifier

The Airmega 400 performed a great job cleansing the air and is quite silent. When the Airmega 400 is on low, the only way to tell it’s operating is by feeling the breeze. My sound meter measured 39 decibels at four feet, quieter than a PC. Sound meter reported 55 decibels with the fan on high, still softer than a conversation.

It worked best when I was frying in the kitchen, my wife was vaping inside, and I was burning incense — not all at the same time, that’d be ridiculous. When the purifier’s pollution sensor detected irritants, the LED turned red (unhealthy) and the fan accelerated.

Airmega 300 400 Filter Configuration

I like the Airmega 400‘s Smart mode and Energy Star certification. In Smart mode, the fan shuts off after 10 minutes of low pollution. When it detects contaminants in the air, it automatically restarts until the levels return to normal. This saves money on electricity.

The Airmega 400 is easy to clean. The filter indication tells you when to clean the pre-filters, which is every two weeks depending on your home’s pollution level. I just use a hand vacuum to clean them. Coway also suggests wiping out the vents and the pollution sensor every two months to keep them clean.

Pros and Cons

The HEPA filter is the most costly part of an air purifier. The Airmega 400′s replacement filter set includes two filters and is now under $50 on Amazon. Although you only need to replace the filters every few years, it’s still a cost to consider.

The Coway 250 is the industry’s greatest air purifier. While it was comparable to our top recommendations, it wasn’t as successful at eliminating VOCs from the air as our top picks. See their guide for additional information on the best air purifiers.

In summary

Airmega 400 Coverage

Overall, I liked the Airmega 400. When I tested this in the spring, when pollen levels were high, I had less sneezing and eye irritation. The Airmega 400 effectively removes vape clouds, smoke, and dander. Best of all, it’s so quiet I hardly know it’s on.

I highly recommend any of Coway’s air purifiers for fighting indoor pollution.

Which model to buy?

I recommend the Airmega 300 or 400 for large spaces to remove allergens. The 200M is a good choice if you have a tiny space or wish to move the air purifier about. Consider the 300S or 400S if you want your purifier to be smart home compatible.

This smart air purifier detects bad air in my home and switches on automatically

Coway Airmega 400 Smart Air Purifier

Pros: Quiet operation, 15-minute air purification, energy efficient, appealing design.
Cons: Inexpensive replacement filters that don’t remove VOCs.

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