Wildfire season in California isn’t optional. Smoke shows up whether you’re near the fire or 200 miles away, and Wildfire Smoke gets inside faster than most people realize.
Your house isn’t as sealed as you think. Every door gap, window frame, attic vent, and HVAC intake is a potential entry point for smoke particles. And those particles are tiny—way smaller than what standard air filters catch. You need a real plan, not just closing windows and hoping.
Your HVAC System Needs Immediate Attention
Regular HVAC filters are designed for dust and pet hair. Smoke particles? They sail right through standard filters like they’re not even there. You need MERV 13 filters minimum during wildfire season. MERV 16 if your system can handle it without choking.
Check your system’s specs before upgrading filters, though. Higher MERV ratings restrict airflow, and if your HVAC isn’t built for it, you’ll strain the blower motor. HVAC Services Agoura Hills CA can assess whether your system handles upgraded filtration or needs modifications first.
Change filters more frequently during smoke events. Every two weeks instead of every three months. Smoke clogs filters fast, and a clogged filter forces your system to work harder while filtering less effectively. False economy to leave a dirty filter in place.
Seal the Obvious Entry Points
Walk around your house during daylight. Any place you see light coming through is where smoke enters. Door sweeps, weatherstripping around windows, gaps around pipe penetrations—all of it needs sealing.
Foam tape works for windows. Door sweeps for exterior doors. Caulk for cracks around utility lines. Not permanent solutions, but wildfire smoke isn’t a permanent problem. You’re just trying to get through the acute periods when air quality tanks.
Don’t forget the attic. Hot air rises and pulls smoke with it. If your attic ventilation is open to the outside (which it should be normally), smoke can infiltrate and seep down through ceiling penetrations. You can’t seal attic vents permanently without causing moisture problems, but temporary covers during heavy smoke days help.
Create Positive Pressure Inside
This part sounds counterintuitive. Run your HVAC on recirculate mode with upgraded filters. The goal is to create slightly higher air pressure inside your house than outside. When interior pressure is higher, air pushes outward through gaps instead of smoke seeping in.
Box fans with DIY air filters work as supplemental filtration. A MERV 13 filter taped to a box fan creates a crude but effective air purifier. Put one in the bedroom, one in the main living area. They’re loud and ugly, but they move a lot of air through filters during acute smoke events.
Air purifiers with HEPA filters help, but they’re expensive and only clean the room they’re in. Multiple units get pricey fast.
What Doesn’t Actually Work
Wet towels under doors look like they’re doing something. They’re not. Smoke particles are too small for that approach. You need actual sealing or filtration, not damp fabric.
Opening windows “briefly” to air out the house defeats everything else you’re doing. Smoke concentration outside during fires is extreme. Even a few minutes of open windows bring in more particles than hours of infiltration through small gaps.
Monitor air quality with actual data. AQI over 150 means outdoor air is hazardous. Your nose adapts to smoke smell, so you can’t trust whether it “seems bad” or not. Check PurpleAir or AirNow for real-time local readings before deciding whether to go outside or change strategies.
Wildfire smoke isn’t like regular air pollution. It’s concentrated, it penetrates aggressively, and it requires active defense beyond just staying inside.
