Smoke has a way of getting indoors even when your windows and doors are closed. Whether it comes from nearby wildfires, a wood-burning fireplace, cooking, or another outdoor source, those fine particles can make the air inside your home feel anything but clean.
Your furnace filter can help.
For most homes, a MERV 13 furnace filter is one of the best choices for capturing the fine airborne particles associated with smoke, as long as your HVAC system can handle it. If your system is not designed for MERV 13, choosing the highest MERV rating recommended for your equipment is generally the better option.
The important part is finding the right balance between filtration and airflow.
If you're ready to replace your filter, shop furnace filters by size and filtration level to find the right option for your HVAC system.
Can a Furnace Filter Remove Smoke From the Air?
A furnace filter can help remove airborne particles from smoke as air circulates through your HVAC system.
Smoke contains extremely small particles, which means the basic filter designed primarily to protect HVAC equipment may not capture them as effectively as a higher-efficiency filter.
That is where the filter's MERV rating becomes important.
MERV, or Minimum Efficiency Reporting Value, indicates how effectively a filter captures particles within specific size ranges. Generally, a higher MERV rating means better filtration of smaller particles.
If you're unfamiliar with the ratings, our guide to what MERV ratings mean explains the system in more detail.
There is one important distinction, though: filtering smoke particles isn't necessarily the same as removing the smell of smoke. Standard furnace filters are designed primarily for particle filtration. Smoke also contains gases and volatile organic compounds that can contribute to odor, so replacing your furnace filter alone may not completely eliminate a smoky smell.
What MERV Rating Is Best for Smoke?
For smoke filtration, MERV 13 is generally the rating homeowners should consider if their HVAC system supports it.
The U.S. Environmental Protection Agency recommends MERV 13, or the highest-efficiency filter your system can accommodate, for homes using central air conditioning or a forced-air furnace during wildfire smoke events.
Why MERV 13?
MERV 13 filters are more effective at capturing smaller particles than lower-rated filters, including particles in the size ranges associated with fine airborne pollution.
That does not mean every homeowner should immediately install the highest-MERV filter they can find.
Your HVAC system still needs to move enough air through the filter.
MERV 8 vs. MERV 11 vs. MERV 13 for Smoke
If you're deciding between common residential filter ratings, here's the simplest way to think about it:
- MERV 8: Good general-purpose filtration for larger household particles, but not the first choice when smoke filtration is your primary concern.
- MERV 11: Provides improved filtration of smaller particles and may be an option when your system isn't designed for MERV 13.
- MERV 13: Provides greater filtration of fine particles and is generally the preferred option for smoke when compatible with your HVAC system.
Already know which rating you need? You can shop MERV 11 furnace filters or shop MERV 13 furnace filters and narrow your options by the size required for your system.
If you're still deciding, our MERV 11 vs. MERV 13 comparison takes a closer look at the differences between the two.
Is a Higher MERV Rating Always Better for Smoke?
Not necessarily.
Higher filtration efficiency sounds like an automatic upgrade, but your furnace or air handler has to be able to pull air through the filter properly.
A filter that is too restrictive for your system can reduce airflow. That's why we don't recommend choosing a furnace filter based on MERV rating alone.
Check your HVAC manufacturer's recommendations before increasing filter efficiency. If you're unsure what your system can accommodate, an HVAC professional can help determine an appropriate filter rating.
Filter thickness can matter, too. Depending on your system, a thicker media filter may offer more surface area for filtration. Our guide comparing 1-inch vs. 4-inch furnace filters explains why thickness, filter design, and HVAC compatibility all matter when choosing a replacement.
Does a Furnace Filter Remove Smoke Smell?
Not necessarily.
A good furnace filter can capture many of the particles carried in smoke, but smoke odor can also come from gases and other compounds that ordinary particulate filters aren't designed to remove.
Some specialty filters incorporate activated carbon or other odor-control media, but even those should not be treated as a complete solution for heavy or ongoing smoke exposure.
If you're dealing with wildfire smoke specifically, filtration is only one part of protecting indoor air quality. Keeping windows and doors closed when outdoor air quality is poor, limiting activities that create additional indoor particles, and using an appropriately sized portable air cleaner can also help.
For more tips, read our wildfire smoke and indoor air quality guide.
How Often Should You Change a Furnace Filter During Smoke?
Don't rely only on your normal replacement schedule when your home is exposed to significant smoke.
Your furnace filter may collect particles much faster during a smoke event. Check it regularly and replace it when it becomes visibly dirty or begins to smell.
A heavily loaded filter may also restrict airflow, making regular checks especially important when your HVAC system is running frequently.
Once conditions improve, inspect the filter again. Even if it hasn't reached its normal replacement date, installing a fresh filter may make sense after prolonged exposure to heavy smoke.
For everyday maintenance, see how often you should change your furnace filter for the factors that can shorten or extend filter life.
Can I Put a HEPA Filter in My Furnace?
Usually, you should not assume a standard residential HVAC system can accept a true HEPA filter.
HEPA filtration is extremely efficient, but true HEPA filters can also create significantly more resistance to airflow. Many residential furnaces and air handlers aren't designed to accommodate them without modifications.
If you want additional filtration during a smoke event, a portable air cleaner equipped with a HEPA filter can supplement your HVAC filtration without putting additional restriction on your furnace or air handler.
For your central HVAC system, use a filter with a MERV rating your equipment is designed to handle.
Choosing the Best Furnace Filter for Smoke
If smoke is your main concern, start by checking the filter size and MERV rating recommended for your HVAC system.
If your system supports MERV 13, it can provide improved capture of the fine particles associated with smoke. If it doesn't, don't force a higher-efficiency filter into a system that wasn't designed for it. Choose the highest appropriate MERV rating your equipment can accommodate and make sure the filter fits correctly.
And remember: the best furnace filter isn't simply the filter with the highest number on the package. It's the filter that provides the filtration you need while still working properly with your HVAC system.
Ready for a fresh filter?
Shop furnace filters by size and filtration level to find the right replacement for your home.
