Wildfire Smoke Season Home Upgrades: Cleaner Indoor Air for LA and Pasadena Homes

Every smoke season, tiny soot particles from regional wildfires ride the wind into Los Angeles and Pasadena neighborhoods and linger for days. The good news is that a handful of targeted home upgrades can dramatically lower what you breathe indoors while keeping your systems efficient and your space comfortable.

Know Your Air: Monitor AQI and use it to drive home decisions

Before you upgrade anything, set a simple decision rule based on the Air Quality Index. During wildfire events, use the AirNow Fire and Smoke Map and the NowCast AQI to decide when to close up, switch HVAC to recirculate, and run high filtration continuously. The NowCast method translates rapidly changing particle readings into an hourly AQI, which you can check by city or ZIP code.

Local agencies also issue smoke advisories with practical steps for residents. When advisories or your own senses indicate smoke or ash, stay indoors, close windows and doors, reduce outdoor activities, and lean on mechanical filtration. South Coast AQMD and Los Angeles County public health guidance reinforce this approach during smoke events.

Actionable steps

1. Bookmark AirNow on your phone and set a household threshold. Example: if AQI for PM2.5 rises above 100, close windows, set HVAC to recirculate, and begin continuous filtration.
2. Sign up for South Coast AQMD smoke advisories and follow local instructions.
3. Place a small reminder card near your thermostat that lists your “smoke settings” so anyone at home can switch modes quickly.

Upgrade whole-home filtration at the HVAC

Your central system is your biggest lever. During smoke days, fine particles known as PM2.5 are the primary threat, and modern guidance recommends upgrading to filters rated MERV 13 or higher where the equipment allows. Higher efficiency filters capture a much larger share of fine particles and can reduce indoor particle levels dramatically when the fan runs continuously.

ASHRAE’s 2024 Guideline 44 provides building pros with best practices to reduce smoke intrusion, and it aligns with using at least MERV 13 filtration, longer fan run times, and smoke-event operating modes that prioritize cleaner recirculated air. Work with your contractor to confirm that your blower and return paths can handle the added resistance of higher-MERV media, and to adjust fan settings if needed.

Actionable steps

1. Ask for a MERV 13 to 16 media filter if your equipment can support it. Have your contractor check static pressure and blower capacity before upgrading.
2. Seal the filter rack so air cannot bypass the filter. Even small gaps reduce performance.
3. During smoke events, set the fan to “on” or use a schedule to keep it running most of the hour to maximize particle capture.
4. Stock spare filters and change them more frequently during smoke season, since filters load faster when outdoor air is dirty.

Add portable HEPA power and create a clean air room

Even with a strong central filter, portable HEPA cleaners give you targeted protection where you spend the most time, especially bedrooms and a primary living space. Choose units with a clean air delivery rate (CADR) matched to the room size and verify they are certified for sale in California to avoid ozone-producing technologies. California requires portable air cleaners to be CARB-certified, and electronic types must meet a strict ozone emission limit.

When smoke is heavy, designate a “clean air room” that is sealed from outdoor air and actively filtered. EPA recommends picking a comfortable room, closing windows and doors, minimizing indoor particle sources, and running a right-sized portable air cleaner on high. If commercial units are unavailable or unaffordable, a well-built DIY air cleaner using a box fan and MERV 13 filter can help as a temporary option, but EPA does not recommend DIY units as a permanent substitute for certified devices.

Actionable steps

1. Size portable cleaners by CADR to at least match your room’s square footage. Place them where airflow is unobstructed and run them on higher settings during smoke intrusions.
2. Choose CARB-certified units only. Check the CARB list before you buy to ensure low or near-zero ozone emissions.
3. Prepare a clean air room plan for your household. Identify the room, list the steps to seal it, and store any needed supplies there so you can act quickly on high AQI days.

Keep smoke out: air sealing, window and door improvements, and smarter ventilation modes

Filtration is only part of the story. Smoke enters through leaky windows, doors, recessed lights, attic hatches, and unsealed penetrations. Tightening the envelope reduces how much your filters must capture and keeps indoor levels lower for the same fan energy. During active smoke periods, keep windows closed, avoid bringing in outdoor air, and run systems on recirculate. This aligns with EPA’s clean room guidance and Los Angeles County recommendations for HVAC operation during wildfires.

If your home uses balanced ventilation or an HRV or ERV, consult your contractor about a smoke-event mode that maintains pressure and comfort while maximizing filtration. Where feasible, upgrade return grilles and filter boxes for better sealing and consider weatherstripping, door sweeps, and caulking to cut infiltration. ASHRAE’s wildfire guideline underscores the value of comprehensive building measures to reduce smoke intrusion, not just filters alone.

Actionable steps

1. Add or replace weatherstripping on operable windows and doors. Install tight door sweeps at exterior doors.
2. Seal obvious penetrations at the attic, garage, and crawlspace. Replace leaky recessed fixtures with airtight, insulation-contact rated versions during remodels.
3. Ask your contractor to set or program a “smoke mode” that emphasizes recirculation and high filtration and to verify fresh-air intakes are closed during active events.
4. Avoid indoor particle sources on smoke days. Do not burn candles or wood and minimize high-heat cooking that produces aerosols. South Coast AQMD explicitly advises avoiding indoor combustion to protect indoor air quality.

Monitor and maintain: sensors, routines, and seasonal service

You cannot manage what you do not measure. Low-cost sensors placed indoors can help you see if your upgrades are working and when to switch modes. Public health guidance in California notes that indoor sensors can provide useful feedback on the effectiveness of filtration and other strategies during smoke events.

Build simple routines so your home is always ready. Keep a filter inventory, note last-change dates on the HVAC cabinet, set reminders for seasonal tune-ups, and review your smoke playbook each June. When AQI spikes, close up, set the system to recirculate, and run filtration continuously until levels fall. EPA and AirNow materials provide clear checklists for these steps, including quick guides for creating and operating a clean room at home.

Actionable steps

1. Place one indoor PM2.5 sensor in your main living area and another in your clean air room if you have one. Use the readings to confirm your HVAC setting changes are working.
2. Create a one-page “smoke plan” for your household that lists AQI thresholds, who flips which switches, and where supplies live.
3. Schedule pre-season maintenance to verify filter fit, fan operation, and duct integrity, then inspect again after heavy smoke periods.

Safety and compliance in California

When purchasing portable air cleaners, verify that the model is CARB-certified to ensure low or near-zero ozone emissions and to comply with California’s sale requirements. This applies to portable devices and, for electronic types, to in-duct cleaners as well.

When hiring a contractor to perform filtration upgrades, ventilation adjustments, or weatherization work, confirm licensing and insurance through the Contractors’ State License Board. You can look up a company by name or license number and review license status before work begins.

How FTR Renovation & Build can help

FTR Renovation & Build plans smoke-season upgrades as part of broader remodels and targeted retrofits, from better filter racks and sealed returns to window and door improvements that reduce infiltration. Explore recent whole-home projects in Santa Monica and across Los Angeles to see how performance upgrades are integrated with design. Then schedule a walk-through to identify quick wins before the next smoke event.

Cleaner indoor air during wildfire season comes from a simple playbook. Monitor AQI, upgrade to at least MERV 13 filtration at the HVAC, add portable HEPA units and a prepared clean air room, tighten the building shell, and keep a maintenance routine that you can activate whenever smoke returns. With a few smart upgrades and a clear plan, LA and Pasadena homes can stay comfortable and healthier through smoke season.