Filtering Your Indoor Air During Fire Season

September 17, 2020
Forest Fire at Night.Wildfire burning forest trees in the mountain.Wildfire caused by humans.

Filtering Your Indoor Air During Fire Season

When the air outside is smoky, is it possible to filter your indoor air to make it healthier for you and your family? During fire season, customers ask us what we suggest.

The most important thing to remember is that not all filters clean the air you’re breathing. Economy filters, for example, remove pollen and large dust particles, but not smaller particles such as mold, pet dander, dust mites, viruses, bacteria, and those that become airborne in a forest fire.

But there are plenty of options that will screen out the tiniest particles, making the air in your home cleaner and healthier. In fact, there are options that can filter air up to 100 times more effectively than a typical economy filter.

But before we go through filter options, let’s talk about how to temporarily shut off the outdoor air coming into your home.

How to stop outdoor air from coming in through your HVAC system

If smoke blows into the area and you want to shut off the outdoor airstream fast, here’s a temporary fix. Note: make it temporary. If you keep the vents closed, it can make humidity to rise in your home, which can cause damage to your flooring, furnishings, and other items. Be sure to set a reminder on your phone so you don’t forget to switch it back.

  • On some HVAC units, look on the side of your furnace for a device that looks like a lamp timer. This device, when it activates, opens a damper to pull in fresh outdoor air.
  • Push the pins on the device toward the outer ring to halt outdoor retrieval. Or simply flip the switch to the “0” to turn it off.
  • Again, once the outdoor air has cleared, you must remember to return the pins to their original position.

Alright. Now that we have that squared away, what are your filtration options?

MERV-rated replaceable filters

Higher rating = more and smaller particles filtered out of the air. Take a look at the different MERV ratings and talk with your HVAC technician about which one is best for your system.


A standard-issue MERV 6 filter will protect your equipment but not the air quality in your home. Its function is to keep the system clean so it can function properly. They’re designed to filter out dust, lint, and pollens.


A MERV 8 filter captures a broader spectrum of particles. In addition to dust, lint, and pollen, it removes dust mites and mold. According to most manufacturers, you should replace them every two to three months.


MERV 11 filters will capture all of the above plus pet dander, smog, smoke, and airborne particles from coughs and sneezes. These are typically used for filtering out air pollutants and irritants. For folks with allergies and sensitivities, these filters can make a big difference.


Yes, there’s even more stuff you can filter out of the air! A MERV 13 filter also grabs viruses and bacteria as well as all the other stuff.

Integrated whole-house filtration systems

Your HVAC technician can also talk with you about options for permanent filters that attach to your system.

Air Scrubber

Air Scrubber by Aerus is a duct-mounted unit that attaches to your HVAC system. Using UV light and an oxidation process, this system continuously pulls contaminants from the air to purify your space and keep the air and surfaces in your home cleaner.

Trane CleanEffects Air Cleaner

Certified by the Asthma and Allergy Foundation of America, this electrostatic air cleaning system removes the vast majority of airborne particles from the air in your home—up to 99.98% of them. This makes the CleanEffects system eight times more effective than HEPA filters and 100 times more effective than a standard 1-inch replaceable filter.

If you’d like to talk one-on-one with someone who can help you decide what kind of filtration system is right for you, call or text us at 360-491-7450. We’d love to help.

Need to know how often to change your filters? See our post about it!

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