Best Air Purifiers

Updated November 2021
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Bottom Line

After going through an intensive research process to narrow down our short list of top products in this space, we tested most of our top five — the AirDoctor 4-in1 Air Purifier and the Blueair Pure211 — to be sure that these products are worth your time. Guided by experts, we spend hours looking into the factors that matter and test to verify manufacturer claims.

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Buying guide for the best air purifiers

Having clean, mold-free air circulating about your house is one of the easiest things you can do to protect the health of your family. Just plug it in, turn it on, and breathe easy. At least that's all you need to do if you have the right air purifier.

A model with a number of speeds that can adequately handle the volume of air you need purified is your primary concern. A timer and a UV light can be desirable features, but investing in a quality filter is essential. If you can, find a model with a cleanable HEPA filter, which can save you a great deal of money over the years.

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Similar to eating organic food to avoid potential toxins, you can use an air purifier to remove toxins from the air.

Types of air purifiers

When selecting an air purifier for home use, you typically have two options: portable and whole-home air purifiers.

Portable air purifiers

We focus on portable models in our product list and shopping guide. Portable air purifiers are typically designed to clean the air in a single room. You can move these models from location to location; people often place them in the bedroom, but you could locate your air purifier anywhere you wish. Most weigh less than 25 lbs, so they aren’t difficult to carry around the house.

Whole-home air purifiers

A whole-home air purifier affixes to the furnace or ductwork in your home. It cleans the air as it passes through the ducts.

This type of air purifier is rare; it’s more of a specialty purchase. You’d probably buy this type of unit at the time you buy a new furnace.

Air purifier filter maintenance

As the owner of an air purifier, you will incur an important ongoing cost: replacement air filters. The manufacturer will include at least one air filter with your initial purchase.

Some units don’t just have one filter; they actually have two or three that work together. You may be able to change some filters less often than others, saving you a bit of money over time.

Here’s a look at the types of filters an air purifier may require:

HEPA filter

This is the primary filter in your typical portable air purifier. It removes the tiny airborne particles that you cannot see, so it’s an important filter to clean regularly. Check your product manual to see how often you should change the primary HEPA filter. Most manufacturers recommend changing this filter at least every three months.


Some units have a pre-filter that captures larger particles, including dust. These pre-filters are usually smaller (and cheaper) than the primary HEPA filter. Check this filter for debris and change it often when it’s dirty, and you’ll preserve the HEPA filter for a longer period.

Second pre-filter

Some units contain a second pre-filter that attempts to catch small particles before they encounter the HEPA filter. In some instances, this “middle” filter is designed to target odor molecules.

Air purifier operation costs

You can expect to spend anywhere from $25 to $500 annually on filter replacements. This is a broad range indeed; we recommend that you research filter replacement costs before investing in a new unit.

You may be tempted to change the filter less often than the manufacturer suggests in order to save money. Don’t do it. Operating an air purifier with a dirty filter wears down the unit and could cause it to malfunction or fail.

Here are some tips on how to save money on the ongoing cost of running your air purifier:

  • Keep the house clean. The more dust and contaminants you remove from your home, the better your purifier will work. Eliminating dust from the home before it has a chance to reach the purifier means your filters will last longer.

  • Ask smokers to take it outdoors. If you have smokers in your home, have them step outside to smoke. This helps preserve the cleanliness of the air inside the home. Cleaner indoor air means the air purifier has fewer toxins to filter, allowing filters to last longer.

  • Buy an energy-efficient purifier. Some air purifiers are better at running at low power than others. Granted, you won’t save hundreds of dollars in energy costs by picking an Energy Star unit. Nevertheless, an energy-efficient unit will save you a bit of money in the long run.

  • Invest in washable filters. If the cost of replacement filters overwhelms you, consider buying a purifier with washable filters. You can reuse a washable filter multiple times.

How an air purifier works

Individual air purifiers vary in design, but most units share a similar process for cleaning the air. Here are the basics —

  • Step One: Powered by a fan, the unit draws air from the room into the interior of the purifier. If your purifier has a pre-filter, the air will pass through the pre-filter in this step.

  • Step Two: The unit’s fan continues to pull in air, propelling it upward. If there’s a second pre-filter in the unit, it will be in the middle of the unit.

  • Step Three: As the air moves toward the top of the purifier, the fan pushes it through the final filter, which is usually a HEPA filter. As it passes through the HEPA filter, the air returns to the room through the top of the unit.

Choosing a size

When you’re studying air purifiers, take a close look at the manufacturer’s specifications. In this list, you should see measurements that help determine the purifier’s volume capacity. Here are some tips for picking the right size for your needs:


The working capability of the air purifier is usually provided in square footage. You’ll want to measure the size of your targeted room, multiplying length by width, to determine its square footage. Select a unit that has a coverage rating higher than the room in which it will reside. This ensures that the air purifier will be able to handle its load without overstressing the machine.

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Did you know?
If you have a higher-than-average ceiling in your target room, you’ll need a machine with an even higher square footage rating to compensate for the extra space.

ACH/CFM rating

Some manufacturers list a CFM (cubic feet per minute) rating in the specification list. This figure shows the amount of air the machine can process every minute. With a little math, you can figure out how many times the air purifier will draw all of the room’s air through it.

Other units come with an ACH (air change per hour) rating. This figure reflects how often the machine will draw the room’s air through it. An air purifier that has an ACH rating of three would be able to pull a room’s volume of air through the machine three times per hour.


  • If you want an automatic unit, look for one that changes its fan speed based on the airborne dust particles it’s measuring.

  • Unfortunately, air purifiers do not work well to eliminate "vog" (smog caused by volcanic eruptions). Run an air conditioner and/or dehumifier instead. You can also soak a towel or cheesecloth in water and baking soda, ring it out, then place over a box fan on low to medium.  

  • Some units have automatic timers that allow you to run them only at certain times of the day.

  • To improve indoor air quality, avoid burning candles and running wood-burning appliances as much as possible.

  • One differentiating factor between air purifier models is the amount of noise they generate. Some manufacturers provide a decibel level in the product’s specs.

  • Portable air purifiers will have a rating for the smallest size of pollutant they can filter. Most units filter pollutants down to a size of 0.3 microns.

  • Some air purifiers work with particles as small as 0.003 microns. A 0.3-micron filter is typical. For comparison, a human hair is about 50 microns in diameter.

  • To pick a location for your air purifier, consider the room where you spend the most time in your home.
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HEPA filters are the most effective type of filtration used with air purifiers, so look for this designation on your unit.


Q. Beyond the air purifier, how can I keep the air in my home cleaner?
Simply keeping a home clean will reduce the number of pollutants inside. Vacuum and remove dust regularly. Make sure the filters on the vacuum are cleaned often, and change your furnace filter regularly, too. If you smoke cigarettes or cigars, do so outside the home as much as possible.

Q. What can I expect to pay for an air purifier?
Portable units have a wide price range, running from about $300 to $1,500. Units with a higher price offer more features. For example, you’re more likely to find adjustable fan speeds and the ability to filter finer particles on a high-priced air purifier.

And, as previously mentioned, remember that you’ll incur ongoing filter replacement costs with all of these units.

Q. I want an extremely quiet air purifier. Can I purchase one without a fan?
A purifier without a fan will run more quietly than a purifier with a fan. However, a unit without a fan won’t circulate air as effectively as a unit with a fan. As such, you’d be trading the quiet of a fan-less purifier for a less efficient machine.

Instead, consider purchasing an air purifier with multiple fan levels. You can turn down the fan’s speed to reduce noise while sleeping. And you can set the fan at higher speed when more extensive air cleaning is needed.

Q. What exactly do air purifiers filter out of the air?
Most home-based air purifiers filter the same types of airborne particles: dust, pollen, mold spores, pet dander, and smoke particles. Portable air purifiers don’t typically filter things like VOCs (volatile organic compounds) from paint or glue.

Q. What does HEPA mean?
A HEPA filter, otherwise known as a “high efficiency particulate air” filter, contains a tight mesh that traps particles as air is forced through the filter. (The air molecules are small enough to pass through the mesh.)

HEPA filters are able to trap smaller particles than standard types of filters, such as you’d find on a furnace. This allows them to take allergens out of the air.

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