Best for large rooms in air purifiers for smoke
The big-room smoke pick: a smoke CADR of 328 drawing air through both sides, with app control and a five-year motor and electronics warranty. US only.
Our score: 8.2/10 out of 10Researched, not lab-tested
- Smoke CADR
- 328 CFM
- Room size (maker)
- 780 sq ft
- Filter life
- 12 months
- Noise, lowest
- 22 dB(A)
Is it right for you?
Pros
- Smoke CADR 328, about 780 sq ft at 4 air changes an hour
- Two Max2 filters (carbon plus HEPA), one each side
- IoCare+ app with real-time air quality and schedules
- Quiet at 22 dB(A) on its lowest speed
- Five-year motor and electronics warranty
Cons
- Large and heavy at 24.7 lb
- Two Max2 filters to replace about once a year
- Wi-Fi needs a 2.4 GHz network
- US only: Coway says the Airmega range is sold in the US only
- Best for
- US open-plan living areas and large rooms during wildfire smoke, for owners who want app control and long cover.
- Not for
- Small bedrooms (the Mighty does the job), or Canadian buyers: Coway sells this model for the US only.
Our verdict
When smoke fills an open-plan main floor, a small purifier can’t keep up, and the 400S is the larger unit we’d look at. Coway lists a smoke CADR of 328 (328 dust, 400 pollen) and rates it for 780 sq ft at four air changes an hour, or 1,560 sq ft at two. It draws air through both sides, each with a washable pre-filter and a Max2 filter that combines activated carbon and HEPA.
The IoCare+ app shows live air quality and runs the timer and schedules, though its Wi-Fi needs a 2.4 GHz band. It runs at 22 to 52 dB(A) and draws 66 W. Coway covers internal parts for a year and the motor and electronics for five. Its store says the Airmega range is sold for use in the US only, so we list this model for the US. For a bedroom, the Coway Airmega Mighty is enough; see all the air purifiers for smoke.
Using it during smoke events
Health Canada’s rule of thumb is a smoke CADR of at least two-thirds of the room’s floor area in square feet, assuming 8 ft ceilings. A smoke CADR of 328 covers about 490 sq ft by that rule.
During smoke: keep windows and doors shut, set up a cleaner-air room with the purifier where you spend most time, and avoid air cleaners that make ozone. A purifier cleans indoor air only: outdoors, a well-fitting NIOSH N95 cuts fine particles, though not the gases in smoke (see our N95 masks). Sources: Health Canada on choosing a purifier and the EPA smoke fact sheet.
Take the plastic off both Max2 filters before first use and refit them green side towards the unit. Rinse or vacuum the pre-filters when Pre Wash lights, replace both Max2 filters about once a year, and clean the pollution sensor every 2 months. Our guide to air purifiers for wildfire smoke compares the picks.
Specs
Coway Airmega 400S Smart Air Purifier (AP-2015E)
Cleaning
| Smoke CADR | 328 CFM |
|---|---|
| Room size (maker) | 780 sq ft |
| Carbon filter | Yes |
| Dust CADR | 328 CFM |
| Pollen CADR | 400 CFM |
| Filter grade | HEPA (maker states HEPA) |
Filters
| Filter life | 12 months |
|---|---|
| Replacement filter | Airmega 400 Max2 filter set (2 filters) |
Noise and power
| Noise, lowest | 22 dB(A) |
|---|---|
| Noise, highest | 52 dB(A) |
| Power draw | 66 W |
Other details
| Warranty | 1 year |
|---|---|
| Weight | 24.7 lb |
| App control | Yes |
Maker’s figures, checked 3 Nov 2026.
Coway Airmega 400S questions
How big a room can the Coway Airmega 400S clean?
Coway rates it for 780 sq ft at four air changes an hour and 1,560 sq ft at two, with a smoke CADR of 328. By Health Canada’s two-thirds rule, that CADR suits about 490 sq ft, so size to the smaller figures in heavy smoke.
How do I clean the 400S pre-filters?
When Pre Wash lights, take off both side covers and pre-filters, vacuum them or rinse them, dry them in the shade, refit, then hold Pre Wash to reset. The unit won’t start if a cover is fitted wrongly.
Why won't my Airmega 400S connect to Wi-Fi?
Coway says it needs a 2.4 GHz band; a 5 GHz-only network won’t work.
