Wildfire smoke and indoor air quality guide for BC
Wildfire smoke has become a fixture of the BC summer. For weeks at a time, Metro Vancouver and Fraser Valley skies turn hazy and the air quality health index climbs into risky territory. Fine particulate matter in smoke — the tiny PM2.5 particles — penetrates deep into the lungs and bloodstream, and it’s especially harmful to children, seniors, pregnant people and anyone with asthma, heart or lung conditions. When the air outside is hazardous, your home becomes your refuge, and its indoor air quality matters enormously.
The challenge is that smoke season often overlaps with heat waves, so you can’t simply open windows to stay cool. That makes your HVAC system central to smoke defence: it can filter the air you breathe and, if it provides cooling, let you keep the house sealed and comfortable at once. But an ordinary furnace filter isn’t built for smoke — it’s built to protect the equipment, not your lungs. Getting the most from your system takes the right filter, the right settings and a few home strategies.
HeatLand installs and services heating, cooling and air-quality equipment across Metro Vancouver and the Fraser Valley. This safety-forward guide explains how to defend your home’s air during smoke season and how your HVAC system can do far more than most homeowners realize.
Upgrade your HVAC filtration for smoke, safely
The filter in your furnace or air handler is your home’s built-in air cleaner — but only if it’s rated to capture fine smoke particles. Filters are rated by MERV: standard filters (low MERV) protect the equipment but let fine smoke through, while higher-MERV media filters capture much more of the PM2.5 that makes wildfire smoke dangerous. Upgrading to a higher-MERV filter your system can properly handle is one of the most effective steps you can take.
The important caution: not every furnace can push air through a very dense filter. Too restrictive a filter chokes airflow, strains the blower and can hurt both efficiency and the equipment. The right move is to match filter rating to what your system is designed for, or to install a dedicated high-capacity media filter cabinet or a whole-home air cleaner sized for your unit. A licensed technician can tell you the highest-rated filtration your specific system can safely use, and recommend upgrades if you want hospital-grade whole-home filtration. HeatLand can assess your equipment and set up smoke-capable filtration that protects your air without starving your system of airflow. Change filters more often during smoke season, as they load up fast.
Use your system settings the smart way
How you run your HVAC during smoke events matters as much as the filter in it. Most thermostats let you set the fan to run continuously rather than only when heating or cooling. Running the fan on ‘on’ rather than ‘auto’ during smoke keeps air moving through the filter constantly, steadily cleaning your indoor air instead of only when the system cycles. Just remember it’s the filter doing the work, so continuous filtering only helps if you have a good filter installed.
Critically, make sure your system isn’t pulling in outdoor air during smoke. Some HVAC setups, ventilators (HRV/ERV) or fresh-air intakes deliberately bring outside air in — great normally, counterproductive when that air is smoky. Know whether your system has an outdoor-air intake or economizer and how to close or bypass it during smoke events; a technician can show you. Also avoid running exhaust fans (kitchen, bathroom) more than necessary, since they draw smoky replacement air in through gaps. And keep cooling running if you have it — being able to stay comfortable with the house sealed is what makes smoke defence sustainable over days. HeatLand can walk you through the right settings for your specific equipment.
Seal your home and set up a clean-air room
Filtration works best when smoke isn’t pouring in faster than you can clean it. During a smoke event, keep windows and doors closed and minimize how often you open exterior doors. Weatherstripping and sealing obvious gaps around doors, windows and other openings reduces smoke infiltration and, as a bonus, improves year-round energy efficiency. A tighter home holds cleaner, cooler air.
Even with good whole-home filtration, it’s wise to establish one clean-air room — usually a bedroom — where air quality is kept as high as possible. Choose a room you can keep closed, run a properly sized portable HEPA air cleaner in it, and make it the place vulnerable family members and pets spend the most time, especially for sleeping. Portable HEPA units complement your HVAC filtration and are invaluable in homes without ducted systems. Size the unit to the room for it to be effective. This layered approach — a sealed home, whole-home HVAC filtration, and a portable-HEPA clean-air room — gives you defence in depth so that even during a prolonged smoke event, there’s always somewhere in the home with genuinely clean air to breathe.
Plan ahead and know when to get help
Smoke season is predictable enough to prepare for before it arrives. Stock up on the right replacement filters early, because they sell out during heavy smoke events. Confirm your HVAC and any portable air cleaners are working before you need them, and know your system’s settings and any outdoor-air controls in advance. If cooling matters for your household — and during combined heat-and-smoke events it’s vital — get your AC or heat pump serviced or installed in spring, ahead of the rush, so you can keep the house sealed and comfortable when smoke hits.
Stay informed during events by monitoring the local air quality health index and following public-health guidance; reduce strenuous activity and time outdoors when readings are high, and take symptoms like coughing, wheezing, dizziness or difficulty breathing seriously, especially for at-risk people. If your home simply can’t maintain acceptable air quality, know where cleaner-air public spaces are. For lasting protection, a professional assessment of your HVAC’s filtration capacity, sealing and cooling is worthwhile — many homes can be upgraded to handle smoke far better than they currently do. HeatLand helps BC homeowners build combined heat-and-smoke resilience so each summer is safer than the last.
Quick Checklist
- Upgrade to the highest-MERV filter your system can safely handle
- Run the HVAC fan continuously (‘on’) during smoke to filter constantly
- Close any outdoor-air intake, HRV/ERV or economizer during smoke events
- Keep windows and doors shut; seal gaps to reduce smoke infiltration
- Set up a clean-air room with a properly sized portable HEPA cleaner
- Stock spare filters early and service cooling in spring, before smoke season
| Strategy | What to do | Why it helps |
|---|---|---|
| HVAC filter | Install highest safe-MERV or media filter | Captures fine PM2.5 smoke particles from indoor air |
| Fan setting | Run fan continuously, not just on ‘auto’ | Cleans air constantly instead of only when cycling |
| Outdoor air | Close intakes, HRV/ERV, economizer | Stops the system pulling smoky air inside |
| Home sealing | Weatherstrip and close gaps; keep doors shut | Reduces smoke infiltration; also saves energy |
| Clean-air room | Run sized portable HEPA in one closed room | Guarantees a genuinely clean space for at-risk people |
| Cooling | Keep AC/heat pump running, serviced in spring | Lets you stay sealed and comfortable during heat+smoke |
Frequently Asked Questions
What furnace filter is best for wildfire smoke?
You want the highest-MERV filter your system can safely handle — higher-MERV media filters capture much more of the fine PM2.5 particles in smoke that ordinary equipment-protecting filters let through. The catch is that too dense a filter can choke airflow and strain your blower. A licensed technician can tell you the best filtration your specific system supports, or install a proper media cabinet or whole-home air cleaner. HeatLand can set this up safely for your equipment.
Should I run my furnace fan during a smoke event?
Yes — set the fan to run continuously (‘on’ rather than ‘auto’) so air moves through the filter constantly, cleaning your indoor air instead of only when the system cycles. This only helps if you have a good filter installed, since the filter does the actual work. Also make sure your system isn’t pulling in outdoor air through an intake or ventilator during smoke. HeatLand can show you the right settings for your equipment.
What is a clean-air room and do I need one?
A clean-air room is one room — usually a bedroom you can keep closed — where you run a properly sized portable HEPA air cleaner to keep air quality as high as possible. It’s where vulnerable family members and pets should spend the most time, especially sleeping. It complements your HVAC filtration and is essential in homes without ducted systems. Layering a sealed home, whole-home filtration and a clean-air room gives you reliable defence during long smoke events.
Can my air conditioner filter wildfire smoke?
Your AC or heat pump moves air through your system’s filter, so with the right filter installed it does help clean indoor air — and just as importantly, cooling lets you keep windows and doors closed during the heat that often accompanies smoke. On its own the cooling function doesn’t remove smoke; the filtration does. Service your cooling in spring and pair it with smoke-capable filtration. HeatLand can set up combined heat-and-smoke protection for your home.
Reviewed by the HeatLand Heating & Cooling team — licensed HVAC contractor serving Metro Vancouver & the Fraser Valley since 1999. Rebate programs and product specs change; confirm current details with a written quote and with CleanBC/FortisBC. If you smell gas or your CO alarm sounds, stop, leave, and call a licensed technician or 911.