Wildfire smoke air filtration at home comes down to two moves: filter the air you already circulate with a MERV 13 filter or better, and stop pulling smoky outdoor air in while the smoke is thick. A heat pump can help with the first, but only if it is a ducted system with a proper filter slot. Most wall-mounted ductless heads do very little for fine smoke particles, so those homes need a portable HEPA air cleaner as well. Here is how to set up each type of Greater Victoria home before the next smoky summer.
What filter rating stops wildfire smoke?
The fine particles in wildfire smoke (PM2.5) are small enough to slip through ordinary furnace filters. Health Canada's guidance for cleaner air spaces recommends filters rated MERV 13 or higher to remove fine particulate matter, and the US Environmental Protection Agency (EPA) says to choose a MERV 13 filter "or as high a rating as your system fan and filter slot can accommodate".
| Filter | What it is good for | Use during smoke? |
|---|---|---|
| Washable mesh (typical ductless head) | Dust, lint, pet hair | Not enough on its own |
| MERV 8 pleated | Everyday dust; often used as a pre-filter | Better than nothing, not recommended for smoke |
| MERV 13 pleated or media | Fine particles including smoke | Yes: the recommended minimum |
| Portable HEPA air cleaner | Fine particles in one room | Yes: the best option for a bedroom or ductless home |
Health Canada describes a two-stage setup for larger systems: a MERV 8 pre-filter in front of a MERV 13 or higher filter. It also gives a simple test that filtration is working: indoor PM2.5 readings lower than outdoor readings.
Ducted heat pump: how to turn it into a whole-home air cleaner
A central ducted heat pump moves all the air in the house through one filter, which makes it the strongest option for wildfire smoke.
- Check the filter slot. Note the size and depth printed on your current filter. A 1-inch slot can take a MERV 13 filter, but a deeper media cabinet (often 4 or 5 inches) gives the same capture with less airflow restriction.
- Confirm your system can handle it. Higher-rated filters are denser. If the fan cannot push enough air through, comfort and efficiency drop. Your installer can check airflow and static pressure and tell you the highest rating your system handles well. That check fits naturally into a regular heat pump maintenance visit.
- Keep a spare. Buy one MERV 13 filter before smoke season. Stores sell out once the sky turns orange.
- Run the fan on "On", not "Auto". The EPA's advice for homes with a high-efficiency filter is to set the fan to "On" so the air keeps moving through the filter while air quality is poor.
- Close or recirculate outdoor air. If your system has a fresh air intake, the EPA says to set it to recirculate or close the outdoor intake damper.
- Change the filter after the smoke. A filter loaded with smoke restricts airflow. Inspect it every few days during a heavy smoke event and replace it when it is visibly dirty.
Ductless mini-split: why it is not a smoke filter
Wall-mounted ductless heads usually come with a washable mesh filter that protects the coil from dust and lint; it is not rated to MERV 13 and will not meaningfully clean smoke from the air. Some models offer optional add-on filters, so check your manual, but do not rely on them as your smoke plan. A ductless heat pump still helps in two ways:
- You can keep the windows shut. On a hot, smoky August day the cooling mode lets you seal up the house instead of opening windows. That is one of the strongest arguments for a heat pump over a heat-only system, covered in our air conditioning guide for Victoria.
- It does not pull in outdoor air. A mini-split recirculates indoor air; it has no fresh air intake to close.
For the filtering itself, add a portable air cleaner in the rooms you use most. If you are choosing between system types for a new install, our ducted vs ductless heat pump comparison weighs this alongside cost and layout, and the ductless mini-split guide covers what those systems do well.
How to size a portable HEPA air cleaner
Portable cleaners are rated by clean air delivery rate (CADR). Health Canada's guidance is to choose one that delivers filtered airflow, for smoke, of at least two to three times the room's volume per hour.
- Measure the room: length x width x ceiling height. A 12 by 14 foot bedroom with an 8 foot ceiling is 1,344 cubic feet.
- Multiply by 2 to 3: that room needs about 2,700 to 4,000 cubic feet of filtered air per hour.
- Divide by 60 to compare with a CADR listed in cubic feet per minute: about 45 to 67 CFM of smoke CADR, at the fan speed you will actually run.
Put the cleaner in the bedroom first. You spend a third of the day there, and a closed bedroom door makes a small cleaner far more effective. If a store-bought unit is not available, the EPA and BC's own air quality warnings describe a do-it-yourself option: a furnace filter attached to a box fan, used when other options are not available.
What about my HRV or ERV?
Heat recovery and energy recovery ventilators bring outdoor air in on purpose, which is exactly what you do not want during heavy smoke. Many units have a recirculation or low setting, and some newer homes have a filter on the supply side. Check your unit's manual for its smoke or recirculation mode and the filter it accepts, and return it to normal ventilation once the smoke passes so moisture and indoor pollutants do not build up. Our guide to HRV vs ERV for Victoria homes explains how each type works.
A smoke-season checklist for Victoria homes
- Sign up for BC air quality warnings and check the Air Quality Health Index (AQHI) for your area.
- Ducted system: one spare MERV 13 filter on the shelf, and the installer's confirmation that your system handles it.
- Ductless or baseboard home: a portable HEPA cleaner sized for the main bedroom.
- Know where your fresh air intake or HRV control is and how to switch it to recirculate.
- Plan one "clean room" with the door shut and the air cleaner running.
If you want a ducted heat pump set up with a deeper media filter, or advice on filtering a home with ductless heads, see our heat pump and air quality services or book a free assessment.