How to genuinely keep smoke out of your home — what filters actually work, what doesn't, and what to do during a red-flag event.
What Smoke Actually Does Inside
PM2.5 particles from wildfire smoke are small enough to pass through a standard 1" pleated filter, lodge deep in the lungs, and recirculate through your home for days after an event ends. Action matters before, during, and after.
Before Smoke Season
Upgrade to MERV 13 or higher in a deep media cabinet (4-5" deep) — sized so airflow stays in spec. Seal duct leaks, especially returns in attics or garages. Verify your fresh-air intake has an automatic damper that can close during events.
During a Smoke Event
Set the thermostat fan to ON (not AUTO) so the filter is constantly cleaning. Close all fresh-air dampers. Create one positively pressurized 'clean room' by running a HEPA portable in a small bedroom with the door closed.
After the Event
Replace your MERV filter (it's now full of fine particulate). Run the system fan 24-48 hours to scrub indoor air. If smoke entered visibly, schedule a duct cleaning — particulate settles in trunk lines and re-suspends every time the system kicks on.
