The Best Furnace Filters to Prevent Allergies

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Sneezing at home? You’re not alone. Millions around the world suffer from symptoms caused by allergens in their home. Things such as pollen, pet dander, and insect droppings can trigger an allergic reaction that is accompanied by coughing, sneezing, and a runny nose.

What types of allergy filters are out there?

Depending on what kind of allergies you have, there may be one or more type of filters that are appropriate. Here are a few different types:

Air filters for pollen

19.2 million Americans have had seasonal allergies or hay fever in the last year. If your allergies are triggered by the bloom of flowers in the spring, using an air filter designed for the removal of pollen will help keep your stuffy nose away.

Fortunately, there are many options for air filters that are specifically designed to remove pollen from your home’s air. When choosing an air filter for pollen allergies, look for a filter with a MERV rating of around 10 to 12.

Many air filters that are able to remove pollen from the air will specifically state that on their packaging. Look for the words “allergy” or “allergen” when choosing an air filter for pollen and you’ll be on the right track.

Quick Pick: Air filters for pollen

Filtrete Micro Allergen Air Filter

6-pack of MERV 11 filters. Captures particles such as dust, pollen, and pet dander.

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Air filters for pets

Contrary to popular belief, there is no such thing as a “hypoallergenic” breed of dog or cat. This is because the allergen is not the pet’s hair. Rather, the allergy comes from the saliva, urine, or dead skin flakes (dander) from the pet. Your pet’s hair simply serves as the medium for the allergen to spread.

Having an allergy from your very own pet can be miserable to live with. Fortunately, you can use your home’s furnace to help combat some of the sneezing and watery eyes that come from pet allergies.

Even better, you’ll be able to freshen up your home by removing pet odors with a furnace filter that contains activated charcoal.

Besides removing pet hair and dander, an air filter with carbon will also remove the stinky odors that pets make.

Quick Pick: Air filters for pollen

Filtrete Micro Allergen Air Filter

6-pack of MERV 11 filters. Captures particles such as dust, pollen, and pet dander.

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Air filters for smoke

If you need to remove smoke from the air in your home, you’ll need an air filter with a high MERV rating. Look for an air filter with a MERV rating of at least 13 for effective smoke removal.

If you need to remove as much smoke from your air as possible, then you’ll want a filter with a high MERV rating – around 15 or 16.

The high filter ratings are needed because smoke particles are extremely tiny. Most normal filters won’t block out these particles. Even though some smoke is captured in a normal filter, far more smoke ends up getting through.

One note of caution – be sure that your furnace’s blower is capable of maintaining sufficient airflow if you are using a strong filter. The stronger a filter is, the more airflow it restricts. A restricted fan motor can lead to failure of your home’s HVAC system.

Quick Pick: Air filters for smoke

Nordic Pure Pleated + Carbon Air Filters

Traps smoke particles and removes odors from the air.

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How to pick the best furnace filter for allergies

Choosing the appropriate MERV rating for your furnace filter is important to prevent the infiltration of allergens into your HVAC system. A MERV rating of 7 or 8 is fine for most household particles and dust.

However, if you need to keep pollen, pet dander, and dust mites out of your home’s air, then you’ll need an air filter with a higher MERV rating.

Using an air filter with a MERV rating of 10 to 14 will help remove fine dust and particles from the air you breathe. The higher the MERV rating, the better the filtration.

If you have sensitive allergies that are triggered by smoke or smog, then you’ll want to get an air filter with a MERV rating on the higher end of the scale. Air filters with MERV ratings of 15 to 16 are able to trap smoke, smog, and even bacteria.

What about other ratings such as MPR, FPR, and HEPA?

Even though the MERV rating is the established industry-standard air filter rating, there are some other rating systems that you might come across. These other rating systems were developed by manufacturers and retailers to give consumers a better idea of what kind of air filter they are purchasing.

MPR rating

The Microparticle Performance Rating, or MPR, is an air filter rating that was developed by 3M to grade air filters based on their ability to filter out particles less than 1 micron. You’ll commonly find MPR ratings on 3M’s Filtrete brand of filters.

While MERV ratings measure the air filter’s ability to filter out both macroscopic and microscopic particles, the MPR rating only measures the ability to filter out microscopic particles from 0.3 to 1 micron in diameter.

MPR ratings are measured on a scale from 100 to 2800, with 2800 being the best air particle filtration rating.

FPR rating

The Filter Performance Rating, or FPR, is an air filter rating that was developed by The Home Depot to give their customers a way to measure the performance of different filters against each other. The FPR rating is measured on a scale from 4 to 10, with the higher number offering better filtration.

HEPA air filters

HEPA air filters are a completely different beast. HEPA air filters exceed the rating of the highest MERV filters. In fact, HEPA air filters are the ONLY air filters that are tested to meet a specific efficiency at a specific particle size.

In order for an air filter to be classified as a HEPA filter, it must meet a minimum efficiency of 99.97% for particles that are 0.3 microns. This means that HEPA filters are at least 50% more effective than the highest MERV-rated filters at removing fine particles.

What are the most common home allergens?

Dust Mites

Dust mites are a common home pest that triggers many people’s allergy symptoms. They are found all over the house, but they thrive in warm environments such as upholstery, bedding, and carpet.

Keep your bedding clean by washing it every week in hot water and dried in a dryer on the hottest setting. Heat will kill dust mites.

Dust mites thrive in a humid environment. So in addition to keeping your home clean and sheets washed, it is also important to keep excess moisture out of your home’s air.

Due to their microscopic size, dust mites are nearly invisible to the naked eye. However, an air filter with a sufficient rating will be able to easily filter out any dust mites from your home’s air.

If the humidity is high in your home, then using a dehumidifier is one way to remove humidity and keep dust mite levels down.

Pets

Pet allergies are not caused by the animal’s hair. Rather, they are caused by your pet’s saliva, urine, or dander. Your pet’s hair acts as the vector for these allergens to spread.

The onset of pet allergies happens quickly, with some owners experiencing allergic reactions a few minutes after coming into contact with their pet.

If you get allergies from your pet, then using an air filter that is rated to remove pet dander from the air can help to alleviate symptoms.

Pollen

Seasonal allergies, or Hay Fever, is usually caused by pollen in the air. During certain times of the year, plants will emit an abundance of pollen that can cause an allergic reaction in many people. Usually, the allergic reaction occurs in the form of eye allergies or a stuffy nose.

Getting an accurate pollen count for your area can help immensely to curb seasonal allergies. Monitoring pollen counts will allow you to limit your exposure to the outside air when counts are high.

To get the latest pollen count for your area, visit the National Allergy Bureau Pollen Count website.

If you need to keep pollen levels down inside your home, using an air filter with a high enough MERV rating will remove pollen from your home’s air.

Replacing a furnace filter? Here’s what to do.

Replacing an air filter in their furnace is something that most homeowners can do themselves. However, there are a few steps that are important to complete to ensure that you are replacing your filter correctly:

Find the correct air filter size

Figuring out the right size is the first step to replacing your furnace’s air filter. To figure out your furnace’s air filter size:

  1. Turn off the power to your furnace. You don’t want the furnace to be on while you’re changing the filter.

  2. Open the filter tray and remove the old filter. The filter tray is usually located between Sometimes, the old air filter will have its size printed on its side. If this is the case, then you’re done! Just use the measurement of the old filter (assuming it fits correctly). If not…

  3. Measure the old air filter. Using a tape measure to measure the size of the old filter will give you a good idea of the size that you need to use for the new one. Keep in mind that most air filters are slightly smaller than their advertised dimensions. For example, an air filter that is advertised as 20” x 20” x 1” will actually measure 19 ½” x 19 ½” x ¾”. If you don’t have an old air filter to measure…

  4. Measure the air filter tray (if needed). Use your tape measure to measure the dimensions of the tray that the air filter sits in. Once again, be sure that your furnace is turned off and disconnected from power before doing this! The dimensions that you measure in the air filter tray are the size of the air filter that you should buy.

    Sometimes, the air filter tray will be slightly larger than the air filter that it was designed for. So it is okay to get an air filter that is slightly shorter than the filter tray- as long as the filter has no large gaps around its edges when it is in the tray.

Choose the proper air filter MERV rating

Choosing the proper air filter MERV rating is critical to maintain the health of your home’s occupants, and the health of your furnace.

  • Too low of a MERV rating won’t catch small particles such as dust mites and pet dander.

  • Too high of a MERV rating will catch fine particles, but will restrict airflow in your furnace. This will cause higher energy costs and possibly more strain on your fan motor.

If you are going to be getting an air filter that can catch fine particles, be sure that your air handler can handle the airflow restriction brought on by the filter.

Since you’ll get lower airflow with high MERV filters, make sure that your furnace is able to maintain sufficient airflow and static pressure with the filter that you choose.

For most residential homes, a MERV rating of 5 to 8 is appropriate. However, if you have allergies, then you’ll need a filter with a MERV rating of around 10 to 14 to ensure that it is filtering particles such as pollen, mold spores, and pet dander.

For more information about air filter MERV ratings, check out our air filter guide.

Replace the air filter

After finding the correct size and proper MERV rating, it’s time to replace your old air filter with the new one.

  • First, turn off your furnace and ensure that everything is completely powered down. Turn off the furnace’s disconnect to be safe. You want to make sure that there is no airflow going through the system while you’re changing the air filter.

  • After the furnace is powered down, remove the filter tray cover (if you have one) and take out the old air filter from the filter tray. Sometimes, the air filter can be difficult to remove, so it helps to use a screwdriver to prop it out of the holder.

    It may be beneficial to have a trash bag nearby to put the old filter inside of after you remove it. You don’t want dust particles dislodged from the old filter all over your house.

  • The next step is to insert the new, clean filter in its place. Carefully slide the new air filter into its slot. After installing your new air filter, replace the filter tray cover.
    If for some reason you don’t have a filter tray cover, you run the risk of sucking in unfiltered dust and other particles. It’s a good idea to keep your filter tray covered with a piece of tape or a furnace filter slot seal.

Quick Pick: Furnace Filter Slot Seal

FilterLock AllergyZone Filter Slot Seal

Eliminates air leakage from your air filter slot.

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Direction of air filter

Which way does the air filter go? Sometimes, your new filter will have an arrow on it that indicates the direction of airflow.

The rule of thumb is that the arrow on the air filter always points towards the blower. This is because the air filter’s frame is built in such a way to be strong when airflow flows in only one direction, not the other.

If your air filter has a wire mesh, then the mesh goes on the side towards the blower. The purpose of the wire mesh is to ensure that the filter is not torn apart by the airflow pressure when your furnace’s blower runs.

If you put the air filter in backward, it runs the risk of collapsing since it does not have enough strength to withstand the airflow from your furnace’s blower.

After installing your new air filter, replace the filter tray cover. If for some reason you don’t have a filter tray cover, you run the risk of sucking in unfiltered dust and other particles.

If don’t have a filter tray cover, then you can use a furnace filter slot seal instead.