Quick Answer
During wildfire season, San Fernando Valley homeowners can improve indoor air quality by keeping windows closed, using HVAC recirculation mode, replacing dirty filters, limiting outdoor air intake, and using properly sized HEPA air purifiers. If smoke odors continue or airflow weakens, schedule an HVAC inspection to check filters, ducts, vents, and indoor air quality concerns.
Wildfire smoke can affect indoor air quality throughout the San Fernando Valley, even when flames are not nearby. Smoke from regional fires can drift across neighborhoods, settle around homes, and enter through small gaps, doors, windows, attic spaces, and HVAC systems.
For many families, the goal during wildfire season is simple: keep outdoor smoke outside and make the indoor air as clean as possible.
Why Wildfire Smoke Affects Indoor Air Quality
Wildfire smoke contains gases, ash, and fine particles. One of the biggest concerns is PM2.5, which refers to particles smaller than 2.5 micrometers. These particles are tiny enough to stay airborne and may irritate the lungs, eyes, throat, and sinuses.
Even with windows closed, smoke particles can enter a home through small leaks, ventilation systems, or HVAC equipment. Once inside, they may continue circulating through the air.
1. Keep Windows and Doors Closed
During smoky conditions, keep windows and exterior doors closed as much as possible. This reduces the amount of outdoor smoke entering the home.
Check for air leaks around doors, windows, attic access points, and vents. Small gaps can allow smoke to enter, especially during windy conditions.
2. Use HVAC Recirculation Mode
If your HVAC system has a recirculation setting, use it during wildfire smoke events. Recirculation helps the system filter indoor air instead of pulling in smoky outdoor air.
Some systems have fresh-air intake settings. During heavy smoke, outdoor air intake should usually be limited unless your system has specialized filtration designed for it.
3. Replace HVAC Filters More Often
Wildfire smoke can clog HVAC filters faster than normal household dust. A filter that usually lasts one to three months may need replacement much sooner during smoke events.
Check your filter if you notice:
- Smoke odors indoors
- Reduced airflow
- More dust near vents
- Gray or black filter discoloration
- Longer HVAC run times
Using the correct filter size is important. A poorly fitted filter can allow air to bypass the filter and carry particles through the system.
4. Consider a Higher-Efficiency Filter
Higher-efficiency HVAC filters may capture smaller particles more effectively. MERV 13 filters are often recommended for wildfire smoke when the HVAC system can safely support them.
However, not every system can handle a high-MERV filter. If the filter is too restrictive, airflow may drop and the system may work harder.
Before upgrading, ask an HVAC professional which filter rating is safe for your system.
5. Use Portable HEPA Air Purifiers
Portable HEPA air purifiers can help reduce fine airborne particles in specific rooms. They are especially useful in bedrooms, living rooms, home offices, and areas where family members spend the most time.
Choose an air purifier that is properly sized for the room. A purifier that is too small may not clean the air effectively.
6. Avoid Creating More Indoor Air Pollution
During wildfire smoke events, indoor air may already be under stress. Avoid activities that add more particles or gases to the air.
Try to limit:
- Burning candles
- Using fireplaces
- Smoking indoors
- Heavy frying or grilling indoors
- Using strong chemical cleaners
7. Watch for Smoke Odors When the HVAC Runs
If your home smells like smoke when the AC or furnace turns on, smoke particles may be trapped in the filter, ducts, vents, coils, or blower components.
Replacing the filter is a smart first step. If the odor continues, schedule an HVAC inspection.
8. Inspect Vents and Registers
Look around supply vents and return grilles for dust, ash, or residue. Visible buildup may indicate that smoke-related particles have entered the airflow system.
Do not ignore ash near vents, especially after days of poor outdoor air quality.
9. Schedule an HVAC Inspection After Heavy Smoke Exposure
A professional HVAC inspection can help identify problems that are not visible from the outside. The technician can check filters, ductwork, blower components, coils, vents, airflow, and overall system condition.
This is especially helpful if your home has lingering smoke odors, weak airflow, dirty filters, or family members with respiratory sensitivities.
Final Thoughts
Wildfire smoke can reduce indoor air quality throughout the San Fernando Valley, but homeowners can take practical steps to protect their homes.
Keep smoke outside when possible. Use proper HVAC filtration. Replace dirty filters. Add HEPA air purification where needed. And if smoke odors continue, have your HVAC system inspected.
Cleaner indoor air starts with a well-maintained HVAC system and a smart wildfire season plan.
Frequently Asked Questions
Can wildfire smoke enter my home even if windows are closed?
Yes. Smoke can enter through small gaps, ventilation systems, attic spaces, doors, windows, and HVAC equipment.
Should I run my HVAC during wildfire smoke?
In many cases, running the HVAC system with clean filters and recirculation mode can help filter indoor air. Avoid pulling in smoky outdoor air.
What HVAC filter is best for wildfire smoke?
MERV 13 is often recommended when the HVAC system can safely support it. Some systems may require a lower-MERV filter to maintain airflow.
Do HEPA air purifiers help with wildfire smoke?
Yes. Properly sized HEPA air purifiers can help reduce fine smoke particles in individual rooms.
Why does my house still smell like smoke?
Smoke odor may come from filters, ducts, HVAC components, upholstery, carpets, curtains, or other indoor surfaces.
