The short answer
Health Canada's general rule is a smoke CADR of at least two-thirds of the room's floor area in square feet, for a ceiling around 8 feet. A 12 by 10 foot bedroom (120 sq ft) needs a smoke CADR of at least 80. Ignore 'large room' labels and read the smoke CADR number.
- Smoke CADR is a standard, comparable number
- True HEPA filters capture fine smoke particles
- A right-sized unit can run on a quieter setting
- Replacement filters are an ongoing cost
- One unit cleans one room, not a whole home
- Some devices produce ozone, which you should avoid
Why smoke CADR is the number that matters
CADR stands for clean air delivery rate. It is measured separately for smoke, dust and pollen. Wildfire smoke is made of very fine particles, so Health Canada points shoppers to the smoke figure.
Box claims such as 'cleans up to 1,000 sq ft' are often based on fewer air changes per hour than you want during a smoke event. The smoke CADR lets you compare models on the same footing.
Sizing your room
Measure the room you will use most during smoky days, usually a bedroom. Multiply length by width for the floor area, then take two-thirds of that number. For ceilings higher than 8 feet, choose a unit rated for a larger room.
Room calculator: minimum smoke CADR
Enter the floor size of the room you want to clean. No dimensions are saved.
Based on Health Canada's purifier sizing guidance. This is a sizing aid, not a smoke alert. Check your local AQHI during a smoke event.
What to check before you buy
After the size, these details decide whether the purifier keeps working well in your home.
- An AHAM-certified smoke CADR printed on the box or listing
- The price and Canadian availability of replacement filters
- Noise on the speed you will actually run
- No ozone generation: avoid ionizers or 'ozone' features
Frequently asked questions
What CADR do I need for a 150 sq ft room?
For an 8 foot ceiling, Health Canada's general minimum is a smoke CADR of 100, which is two-thirds of 150.
Does an air purifier remove wildfire smoke?
A HEPA purifier sized for the room can reduce fine smoke particles indoors. Keep windows closed and follow public-health advice during a smoke event.
Should I avoid ozone air purifiers?
Yes. Health Canada advises against devices that intentionally produce ozone, because ozone irritates the lungs.
Where can I buy HEPA air purifiers in Canada?
Amazon.ca, Best Buy Canada and Walmart.ca all carry HEPA purifiers. Compare the smoke CADR and filter cost on each listing.
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