When wildfire smoke settles into the Walla Walla Valley, do four things: install the best filter your system can handle, run the HVAC fan on ON (not AUTO) so air keeps passing through it, keep windows and doors closed — including at night — and check the filter weekly instead of monthly, because smoke loads a filter far faster than ordinary dust.
In this guide: Before smoke season · During a smoke event · After it clears
What should I do before smoke season starts?
- Upgrade the filter now, not during the event. Smoke particles are overwhelmingly fine — the kind ordinary fiberglass filters barely touch. Ask us (or check your blower documentation) for the highest MERV rating your system can support without starving airflow.
- Stock spares. During a long smoke event a filter can load up in a week or two. Have at least one replacement on the shelf.
- Seal the easy leaks. Weatherstripping on exterior doors and fresh caulk on leaky window frames does more for smoke than most gadgets.
- Get the tune-up done. A system with a clean blower and coil moves more air through the filter — which is the whole game during smoke season. Our Precision Tune-Up plans handle this on a schedule.
What should I do while the smoke is here?
During a smoke event, your goal is simple: move as much indoor air through a good filter as you can, while letting as little outdoor air in as possible.
- Fan ON, not AUTO. AUTO only filters while heating or cooling runs. ON filters around the clock.
- Windows closed — even at night. Night-flushing is for clean air. On smoke nights, let the AC do the cooling.
- Skip the candles and the frying. Indoor combustion stacks more fine particles on top of what's seeping in.
- Watch the filter weekly. Hold it to the light. Smoke season can clog in days what normally takes months.
What should I do after the smoke clears?
Replace the filter one more time — it took the hit for the whole house. Then air the house out, and if the smell lingers in the ductwork or the system seems to be moving less air than before, have it inspected. Smoke residue on a blower wheel or evaporator coil is a real thing, and it quietly costs you airflow.
Our team has kept valley homes comfortable since 1949, and smoke season has become part of that job. If you want a system-specific answer — what filter your blower can actually handle, whether a whole-home air cleaner makes sense for your house — our indoor air quality service starts with an honest assessment, not a product pitch.
Questions we hear about this
Should I run my HVAC fan during wildfire smoke?
Yes — with a good filter installed, running the fan continuously turns your duct system into a whole-home air cleaner, passing indoor air through the filter over and over. With a clogged or low-grade filter, though, you're just circulating smoky air. Check the filter first, then set the fan to ON.
What filter should I use during smoke season?
The highest-rated filter your system can handle without choking airflow. Wildfire smoke is dominated by very fine particles, so a standard fiberglass filter does little. Many valley systems can take a MERV-13 media filter, but filter thickness and blower capacity matter — we confirm what your system can support before recommending one.
Does a smoke day mean I should open windows at night to cool off?
Not when smoke is heavy. Night-flushing works in clean air, but on smoke days it fills the house with the fine particles you spent all day filtering out. Rely on your cooling system instead, and save window-cooling for after the smoke clears.
Can my air conditioner bring smoke into the house?
A typical central AC recirculates indoor air rather than pulling in outside air, so the unit itself isn't an open door. The real leaks are gaps around windows, doors, and duct returns in unsealed spaces. Ductless mini-splits recirculate as well.
What's the difference between a portable air purifier and a whole-home solution?
A portable unit cleans one room and needs its own filter replacements; a whole-home filter or air cleaner mounted at your furnace treats every room your ducts reach, using the blower you already own. For a single bedroom a portable can be enough — for the whole house, the duct-mounted approach wins on coverage.
Your next step
Once your system is buttoned up for smoke season, the next decision is which filtration upgrade actually earns its cost. We compared the options honestly.
Compare filtration options for smoke
Reviewed by Dennis Davis, President
With College Place Heating & Air since 1975. Family-owned since 1949 · Business license: 600-129-164.