PM2.5 is fine particulate matter 2.5 microns or smaller, the main health concern in wildfire smoke. These particles stay airborne for long periods, travel hundreds of kilometres, and pass easily through windows, doors, and basic furnace filters. Reducing indoor PM2.5 requires a closed-up home plus effective filtration, such as MERV 13 or HEPA.
Why it matters to you
Summer wildfire smoke regularly reaches the Fraser Valley and Lower Mainland, sometimes from fires far away. Opening windows for fresh air during a smoke event lets PM2.5 in, so the HVAC system becomes the main line of defence.
Practical guidance
During smoke events, close windows, run the HVAC fan continuously through the best filter your system can handle, and check filters more often. Ask before smoke season whether your system can carry a higher-MERV filter or needs a dedicated air cleaner.