TLDR

• During wildfire smoke events, set your HVAC system to recirculate indoor air and use high-efficiency filters like MERV 13 to reduce smoke indoors.
• When air quality is unhealthy (AQI 151+), stay indoors and follow local and workplace safety rules to protect yourself and others.
• After the smoke clears, replace filters, clean vents, and prepare by stocking filters and air purifiers for future events.

Wildfire smoke is filling the air across California, creating unhealthy indoor conditions for many homes and buildings. Starting now, homeowners, contractors, and property managers should adjust their HVAC systems to limit smoke from entering indoor spaces. This means setting your system to recirculate indoor air only, closing windows and doors, and using high-quality filters like MERV 13 if your system supports them. These steps help reduce smoke particles inside, improving air quality and comfort during active wildfire events. Following these guidelines can protect your family, tenants, and workers while the smoke lingers outside.

AQI triggers and official guidance in California

When the Air Quality Index (AQI) reaches 151 or higher, the air is considered unhealthy. At this level, stay indoors and keep outdoor air from entering your home as much as possible. Local alerts will guide you on when to take these steps. For workplaces, California’s Cal/OSHA has rules that kick in at AQI 151 and above. Employers must plan indoor work carefully and use filtration systems to protect workers and tenants from wildfire smoke. While building codes usually require ventilation to bring in fresh air, authorities allow temporary changes during smoke events to reduce smoke entry. Make sure to document any adjustments you make, and return your ventilation settings to normal once the smoke clears. Following these guidelines helps keep indoor air safer during wildfire smoke episodes.

What homeowners, contractors, and managers need now

Homeowners should check their filter size and fit carefully. If your HVAC blower supports it, upgrade to a MERV 13 filter, which captures more fine particles like wildfire smoke. To create extra protection, set up a "clean room" using a portable HEPA air purifier. Contractors need to keep stock of MERV 13 filter media, filter housings, and gaskets ready. Offering quick filter-change visits and sending alerts to clients on days with high air pollution helps maintain indoor air quality during wildfire events. Property managers should develop standard smoke response plans. This includes closing outdoor dampers, ensuring economizer functions are turned off, and inspecting filters every 48 to 72 hours when smoke levels are heavy. These steps help keep indoor air safer and systems running smoothly through wildfire smoke episodes.

Filtration, recirculation, and equipment limits

The MERV rating shows how well a filter catches particles. Higher MERV numbers mean finer filtration. MERV 13 filters capture most fine smoke particles, but they can restrict airflow. Check your blower to make sure it can handle the resistance without strain. ERV and HRV systems, which stand for energy and heat recovery ventilators, bring fresh outdoor air inside. During smoke events, turn these off or set them to use minimal outdoor air to keep smoke out. If you’re unsure how to adjust them, call a professional. Ductless mini-splits and most window AC units already recirculate indoor air. Make sure to clean their washable screens regularly. Adding a portable HEPA air purifier helps catch tiny smoke particles that screens can’t trap. This layered approach keeps your indoor air cleaner and safer during wildfire smoke events.

After the smoke: restore, replace, and prep

Once the wildfire smoke clears, it’s time to restore your HVAC system. Replace any dirty filters to keep air flowing cleanly. Wipe down supply and return grilles to remove dust and residue. Listen for weak airflow or unusual noises, and schedule professional service if you notice anything off. Next, reopen outdoor air settings to normal operation. This helps your system bring in fresh air again. Keep a log of what worked during the smoke event to improve your response next time. Setting phone alerts for Air Quality Index (AQI) updates can help you switch modes quickly in future smoke events. Finally, stock up on essential items before the next wildfire season. That includes MERV 13 filters, filter housings, and portable HEPA air purifiers. Being prepared means you can act fast to protect indoor air quality and keep your home comfortable and safe.

Key Takeaways

• During wildfire smoke events, set your HVAC system to recirculate indoor air only and keep the fan running continuously to filter smoke particles effectively. Close all windows and doors, and turn off any outdoor air intake modes like Fresh Air or Economizer to prevent smoke from entering. Use high-efficiency filters rated MERV 13 if your system can handle the airflow resistance; otherwise, use MERV 11 but run the fan longer for better filtration. After the smoke clears, replace dirty filters, clean vents, restore normal outdoor air settings, and prepare for future events by stocking quality filters and portable HEPA units.

Frequently Asked Questions

How can I use my HVAC system to reduce wildfire smoke indoors?

Set your HVAC system to recirculate air, which means it only moves indoor air. Turn the fan to ON so it runs continuously and filter smoke particles. Also, close all windows and doors, and turn off any settings that bring in outdoor air, like Fresh Air or Ventilation modes.

What type of air filters work best during wildfire smoke events?

High-efficiency filters with a MERV 13 rating are ideal because they capture most fine smoke particles. If your HVAC blower can’t handle MERV 13, use MERV 11 filters and run the fan longer to improve filtration. Regularly check and replace filters to keep your system effective.

Are there official rules or guidelines for indoor air quality during wildfires in California?

Yes. When the Air Quality Index (AQI) reaches 151 or higher, local authorities advise staying indoors and limiting outdoor air intake. Workplaces must follow Cal/OSHA wildfire smoke rules, which include improving indoor filtration and adjusting ventilation to protect workers and tenants during smoke events.

What should property managers and contractors do during wildfire smoke events?

Property managers should standardize smoke response plans by closing outdoor dampers, verifying economizers are off, and checking filters every 48 to 72 hours. Contractors should stock MERV 13 filters and offer quick filter changes. Both groups should educate tenants or clients on proper HVAC settings to keep indoor air safe.

Related Topics: California wildfire smoke, HVAC maintenance, air filtration, indoor air quality, home comfort, HVAC filters, air conditioning, heating systems, smoke reduction, HVAC troubleshooting, energy efficiency, HVAC parts