If you’ve ever walked into your house and thought, What is that smell?, your furnace filter may be one of the first things you think about changing.
And sometimes, changing the filter can help. But a furnace filter isn’t an air freshener, and even a high-efficiency filter won’t necessarily remove the gases responsible for an odor.
The short answer is: furnace filters can help with some of the airborne particles associated with odors, but most standard filters are not designed specifically to remove odors themselves.
Understanding the difference can help you choose the right filter and recognize when a smell is telling you there’s another problem in your home.
How Furnace Filters Actually Work
Your HVAC system pulls return air from your home, moves it through the filter and then heats or cools that air before circulating it back through your living spaces.
The filter’s primary job is to capture airborne particles before they continue through the system.
Depending on the filter, that can include things like dust, pollen, pet dander and other airborne particles.
That’s why replacing a dirty filter can sometimes make a home seem fresher. If a filter is loaded with dust, pet hair and other debris, replacing it removes that accumulated material from the air path.
But odors are more complicated.
Many smells are caused by gases or volatile compounds rather than particles. A traditional fiberglass or pleated furnace filter isn't specifically designed to capture those gases.
If you're replacing an old filter and aren't sure where to start, you can shop furnace filters by size and filtration level.
Does a Higher MERV Rating Remove More Odors?
Not necessarily.
MERV ratings describe how effectively an air filter captures particles within specific size ranges. They do not rate a filter's ability to remove odors.
That distinction matters.
A higher-MERV filter may capture more of the fine airborne particles associated with something you can smell, but increasing the MERV rating doesn't automatically turn a furnace filter into an odor-removal filter.
For everyday residential filtration, homeowners may consider MERV 8 furnace filters. Homes where increased particle filtration is desired may benefit from MERV 11 air filters or MERV 13 furnace filters when the HVAC system is designed to accommodate the filter's airflow resistance.
The right choice depends on more than the highest number available. Filter size, HVAC system requirements and your home's filtration needs should all be considered.
What About Activated Carbon Furnace Filters?
If odor reduction is your primary goal, this is where filter construction becomes important.
Some air filters include activated carbon or charcoal media. Activated carbon works differently from standard particle-filtering media. Instead of simply trapping particles, the carbon can adsorb certain gases and odor-causing compounds onto its surface.
That can make carbon-containing filters useful for certain household odors, including some cooking, pet and smoke-related smells.
There are limits, though. The amount and type of carbon matter, and no furnace filter should be expected to eliminate every odor in a home.
If a smell has an ongoing source, controlling that source is usually more important than trying to filter the smell after it enters the air.
What Kind of Odor Are You Trying to Remove?
Before buying a different filter, figure out what you're smelling. Different odors can point to very different problems.
- Pet odors: A good furnace filter can capture airborne pet dander and other particles, but it won't remove an odor source in carpeting, furniture, bedding or a litter box.
- Cooking odors: Particle filtration may capture some airborne material produced while cooking, while activated carbon may help with certain odor-causing gases. Kitchen ventilation and source control are still important.
- Smoke: Smoke contains a mixture of particles and gases, so particle filtration addresses only part of the problem. Our guide to choosing a furnace filter for smoke explains that difference in more detail.
- Musty odors: Don't rely on a furnace filter to solve a persistent musty smell. Moisture, microbial growth or another underlying source may need to be identified and corrected. If you're specifically concerned about airborne mold particles, read what furnace filter is best for mold spores.
- Dusty or stale smells: If your existing filter is extremely dirty, replacing it is a reasonable first step. A fresh filter can remove accumulated debris from the HVAC air path and restore proper filtration.
When an Odor Is More Than a Filter Problem
Your nose can sometimes tell you something your furnace filter can't fix.
Persistent musty smells can point to moisture problems. Burning or electrical odors can indicate an HVAC or electrical issue. If you suspect a natural gas or fuel-related odor, leave the area and follow your utility provider's emergency guidance rather than attempting to solve the problem with a new filter.
In other words, don't use a furnace filter to mask a problem that needs to be corrected at the source.
If an unusual HVAC-related odor continues after obvious household sources have been ruled out, having the system inspected by a qualified HVAC professional is a better next step than simply moving to a higher-MERV filter.
Can a Dirty Furnace Filter Cause Odors?
It can contribute.
Over time, a furnace filter collects dust, pet hair and other airborne debris. Leaving a disposable filter in service well beyond its useful life can allow that material to accumulate while also restricting airflow through the system.
If you're noticing an odor and can't remember the last time you looked at your filter, inspect it.
A visibly dirty filter should generally be replaced according to the filter manufacturer's recommendations and the needs of your home. Homes with pets, higher dust levels or frequent HVAC operation may need more frequent checks.
Choosing the Right Furnace Filter for Your Home
If your goal is cleaner indoor air, don't shop based on smell alone.
Start with the correct filter size for your HVAC system. Then consider the level of particle filtration you need and what your system can accommodate.
Filter thickness matters, too. We carry both 1-inch furnace filters and 4-inch furnace filters for compatible systems.
And if your system takes one of the most common media-filter sizes, you can shop our 20x25x4 furnace filters directly.
The goal isn't to buy the most restrictive or highest-rated filter you can find. It's to choose a filter that fits correctly, provides the filtration you want and is appropriate for your HVAC system.
So, Do Furnace Filters Remove Odors?
Sometimes but that's not what most standard furnace filters are primarily designed to do.
Traditional furnace filters capture airborne particles. That can help with particles associated with smoke, pets, dust and other sources, but many odors are caused by gases that ordinary filter media doesn't capture effectively.
Filters containing activated carbon may provide additional odor reduction for certain contaminants, but even those aren't a substitute for finding and correcting a persistent odor source.
If your current filter is dirty or it's simply time for a replacement, start by finding the correct size and filtration level for your system. Shop our furnace filter collection to compare replacement options for your home.
Frequently Asked Questions
Will a MERV 13 filter remove odors better than a MERV 8 filter?
Not necessarily. MERV ratings measure how effectively a filter captures particles, not odors or gases. A MERV 13 filter captures smaller particles more effectively than a MERV 8 filter, but that doesn't mean it will remove odor-causing gases. If you're considering higher-efficiency filtration, make sure the filter is appropriate for your HVAC system.
Do activated carbon furnace filters help with odors?
They can. Activated carbon is designed to adsorb certain gases and odor-causing compounds, so filters containing carbon may help reduce some cooking, pet, smoke and household odors. Their effectiveness depends on the filter and the source of the smell.
Will changing my furnace filter make my house smell better?
It may, especially if the old filter is dirty and holding dust, pet hair or other debris. However, replacing the filter won't eliminate an odor caused by an ongoing source elsewhere in the home.
Why does my house still smell after changing the furnace filter?
The smell may not be coming from the filter. Persistent odors can originate from moisture, pets, cooking, smoke, drains, carpeting, HVAC components or other sources. If an unusual HVAC-related odor continues and you can't identify the source, consider having the system inspected.
