Air Purifier Guide: How It Works And Our Top Picks | Weather.com

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During my formative years, I suffered horribly from airborne and pet allergies, with side effects as little as a runny nose up to itchy and swollen eyes, hives and trouble breathing. At the time, antihistamines like Claritin were only available from a prescription, so I'd just grab a Benadryl for the days it was severe and struggled not to fall asleep in math class.

I'm definitely not alone in my childhood suffering. According to the Asthma and Allergy Foundation of America (AAFA) and data from the Centers for Disease Control and Prevention (CDC), more than 100 million people in the U.S. experience some type of allergy each year, with allergies ranking as the sixth leading cause of chronic illness in the U.S. Don't forget to check out The Weather Channel's 15-day allergy forecast, especially when you're planning to be outdoors for any length of time..

And while outdoor air quality is certainly a trigger for seasonal allergies, indoor air quality is just as important when it comes to managing your symptoms. In the following guide, we're taking a deeper look into how indoor air pollution can affect you, and why air purifiers may be able to help those suffering from allergies. We also researched some of the top selling air purifiers on the market today and narrowed down our choices based on multiple criteria, including room size, price and functionality.

What Is Indoor Air Pollution?

Indoor air pollution can appear in a variety of forms, from dust and mold to pet dander and smoke. Even cleaning supplies can introduce a number of different chemical compounds into the air. Indoor air pollution can cause a number of side effects, like irritation of the eyes, nose and throat, headaches, respiratory disease and even more serious illness, according to the U.S. Environmental Protection Agency (EPA).

How Do Air Purifiers Work?

Air purifiers, also known as portable air cleaners or air sanitizers, are designed to filter the air of a single room or area to reduce (but cannot completely eliminate) indoor air pollution.

You need to look at the "clean air delivery rate" (CADR) to determine if it's large enough for the size of the room you'll be using it in. Portable air cleaners will get a higher CADR by using a "high-efficiency particulate air" (HEPA) filter.

Portable Air Cleaner Sizing for Particle Removal
(EPA.gov)

CADR was established by the Association of Home Appliance Manufacturers (AHAM) to determine the effectiveness of an air cleaner. The higher the CADR, the faster the unit is filtering the air.

According to the AHAM, the CADR of your air cleaner should be equal to at least two-thirds of the room's area, so in its example, a room with a dimension of 10x12 feet has an area of 120 square feet, and should have an air cleaner with a smoke CADR of at least 80.

Different Types Of Air Purifiers

There are three main types of air purifiers: Ozone-generating air cleaners, electronic air cleaners and filtering air cleaners.

Ozone-generating air cleaners (Not Recommended): These devices purposefully create ozone to clean the air through chemical interactions that will change the compounds of pollutants, but can cause other harmful chemical reactions. Ozone is considered a lung irritant.
Electronic air cleaners (Not Recommended): These can include ionizers and UV light, and are a type of air purification system that uses electrical fields to trap airborne particles, passing contaminated air through a series of charged plates or meshes, according to one source. They are not, however, effective at removing gases and odors, and may also produce ozone and other irritants as well, according to the EPA.
Filtering air cleaners (Recommended): Just as the name suggests, these work by passing air through a filter where pollutants are trapped, usually through carbon filters or HEPA filters.

HEPA filters do not remove gases from the air, but are generally accepted as the best at filtering particles (like dust or pollen). The effectiveness of a HEPA filter is tied to how tightly bound the fibers are, with ratings from MERV 12 to MERV 17, with MERV 13 considered the minimum you should be looking for according to Heathline.

To filter gases, it is suggested by the EPA that you choose a portable air cleaner with an activated carbon filter or other absorbent filter designed to remove gases.

It's also important to note that neither the EPA nor Food and Drug Administration (FDA) recommend any particular air cleaning devices or manufacturers.

Can Air Purifiers Help With Allergies?

According to many sources, yes, air purifiers can help clear the air of allergens like dust, pet dander, pollen and other pollutants. Air purifiers only catch smaller particles and are usually only designed for one room, so it's important to take other steps to keep your environment as clean as possible. Keeping your home well ventilated, clean and your HVAC filters also regularly swapped out can go a long way towards reducing your symptoms.

Air Purifier Picks For 2024

Price: $149.99, plus $10 off coupon at Amazon; $149.99 at Levoit.com

Filter Type: HEPA & Carbon | Effective Range: 219 sq. ft. (up to 1,000 sq. ft./1 hour) | CADR: 140 CFM | App: Yes

LEVOIT Air Purifier Core 300S-P
(Amazon)

Other features:

3-in-1 filtration system: Pre-filter, multi-layer filter and activated carbon filter
Multiple filter options: Pet allergy, toxin absorber, or smoke remover filter
Sleep mode turns off display and reduces noise level
App and voice assistant compatible
Energy Star Certified, FCC Certified, ETL Certified, CARB Certified

The Levoit Core 300S has over 99,000 ratings, 4.7-stars and is the best seller on Amazon, with over 3,000 Levoit products purchased in the past month. There are a number of different packages available, starting with just the basic purifier, different filters and the Wi-Fi-enabled purifier (which is what we've listed).

In Auto mode, the Core 300S will sense changes in the particle pollution and adjust fan speeds, according to the company. In Sleep mode, the air purifier will also work more quietly, which is ideal for light sleepers.

There are over 79,000 5-star ratings alone on Amazon, with the reviews glowing. One reviewer said, "This unit cleans very well for its size. [It] is quiet and it sets up very easily, the Bluetooth connection and functionality are very well laid out and easy to manage."

Another said, "This air purifier has made a significant difference in the quality of air in my apartment. No cigarette smoke, less disgusting odors from neighbors that I share walls with. I would recommend this item." One mentioned, "[I] haven't had indoor allergies bothering me with it running."

For pet owners, multiple reviewers mentioned it is very handy at eliminating odors, "I never seriously considered using an air purifier before, but as a cat owner, I was curious about how it could help combat the persistent smells. I'm happy to report that this device has eliminated almost all of the odors and kept my bedroom feeling clean and fresh."

The main complaints from users were how loud it could be, concerns about the longevity of the product, and some mentioned there was a bad smell with their products and that it didn't clean the odors air as much as they had expected.

Price: $249.99 at Amazon

Filter Type: HEPA & Carbon | Effective Range: 2,640 sq. ft./1 hour | CADR: 598 | App: No

Medify MA-50 Air Purifier V3.0 with True HEPA H13 Filter
(Amazon)

Other features:

3-in-1 filtration system: Pre-filter, True HEPA H13 filter, and activated carbon filter
HEPA H13 Filtration: captures finer particles than HEPA H11, and is trusted to remove particles, allergens, odors, smoke, pollen, pet dander, smog and more, according to the company page
Touch screen with up to 12-hour timer, four fan speeds, sleep mode, filter replacement indicator and child lock
Filter lasts 2,500 hours (approximately 3-4 months)
Energy Star Certified, ETL Certified, CARB Certified in 2023

Most reviewers that use the Medify MA-50 Air Purifier in their home say they keep it at the lowest setting for the quietest results - once you start getting into the higher fan settings, you'll notice it can get loud and vibrate a little. Using it at a higher fan setting for a shorter period of time, however, is recommended if you're trying to reduce some odors in the room (especially after cooking, according to one reviewer).

As one reviewer puts it, "We have a bunch of Medify air purifiers - the small ones for rooms and big ones for bigger areas - and I wish I had this unit just a little earlier." Another said, "This air purifier is the definition of 'you get what you pay for.' In that I mean both the unit and the replacement filters are ridiculously expensive...but they actually work! I am simply amazed by how much better I feel when I'm in the same room as this filter."

Some complaints were that the MA-50 unit didn't last beyond two years, and the noise level at the higher settings is very high.

One of the reasons we picked the MA-50 version (rather than a smaller option like the MA-40) is that this product version came without the UV light and ionizer option, which according to some of our research may be more likely to produce ozone.

3. Best Air Purifier For Medium Rooms: Clorox Air Purifier

Price: $99.99 at Amazon

Filter Type: HEPA & Carbon | Effective Range: 225 sq. ft. (up to 1,000 sq. ft./1 hour) | CADR: ~142 CFM | App: Yes

Other features:

3-in-1 filtration system: Pre-filter, True HEPA filter, and activated carbon filter
Comes with air quality sensor with real-time digital display
1, 4 or 8-hour timer, four fan speeds, auto and sleep mode, child lock
Filter lasts approximately 6 months
Energy Star Certified

If you've decided the Levoit isn't quite right for you, or you prefer to save a few bucks, take a look at the Clorox Air Purifier as a comparable alternative. This size is ideal for medium rooms and depending on the size of your ceilings it can circulate air up to 225 square feet of space five times an hour, according to the company page.

It has over 2,400 total ratings (an average of 4.7 stars), and 1,900 5-star ratings on Amazon. Most of the reviews are also very straightforward, with many saying they are happy with the overall performance, effectiveness and price of the model.

As one stated, "I am very happy with this air purifier. The reviews were good, the cost was reasonable, and it works. I have definitely noticed a reduction in stale odor as well as dust since purchasing this. It's also extremely quiet. It's also small enough to tuck into an unobtrusive yet functional space. My neighbor purchased two as a result of my recommendation."

Another said, "This purifier runs silent and is perfect for a dusty environment like a work office. Practically no set up required. Just plug it in and turn it on. [The] filter can be removed and be blown out with an air hose and be reused so that you don't need to buy expensive replacement filters like so many other models. Recommend!"

As for complaints, it was largely around the longevity of the product, the filters not lasting as long as the company says they should, and not getting as much square footage coverage as expected.

Price: $69.99 at Amazon, Bundle: $125.99, was $139.99 at Blueair

Filter Type: Carbon | Effective Range: 93 sq. ft. | CADR: 60 CFM | App: No

Other features:

HEPASilent™ filtration system: Fabric pre-filter, main filter and activated carbon filter
Three fan modes
Washable fabric pre-filter

The Blue Pure Mini Max is our pick if you're looking for an air purifier for a small room on a decently low budget. If you have a small bedroom or office, this could be all the air purifying power you really need.

One of my colleagues has multiple sizes of the Blueair purifiers, and said "I've noticed a significant change in the air quality of my home. The air is cleaner, less allergens - and even my pets are sneezing less. There are three settings, so if you like white noise you can set it louder, while I prefer it to be quiet. The light sensor that lets you know when the filter needs to be cleaned is also very handy."

There are no air sensors, app or smart assistant options like the Levoit, but if you don't need any of those extra features, why pay for it? The other Blueair models, like the 411 Max, also have high reviews with a few extra bells and whistles if you don't mind paying a little more. No matter the model, though, you should plan to replace the filter every 6 months.

Many of the reviews are pleased with how quiet the Blueair products are, with one saying, "We have been users of Blue Air filters for years…We have noticed an improvement in the amount of dust and the air quality in our home." Another one said, "It is extremely quiet and I noticed a difference in air quality in record time. I suffer [from] allergies this time of year and having this device in my office has been a game changer!"

However, other reviewers complained about a plastic smell from their air purifier and slow customer service times. Some of the Blueair products have been reported to have some ozone emissions though the company does claim its within safe limits.

How We Made Our Decision

Safety

During our research on these products, we attempted to ensure that we avoided ozone and ionizer air purifiers specifically due to the guidance from the EPA. One company on our list, Blueair, has somewhat questionable documentation out there, though has claimed the product is within acceptable standards. While we recommended the Blueair Pure Mini Max because of the general quality of the performance and reviews, if budget and room sizes aren't an issue, we might suggest upgrading to the Levoit.

First-hand testing

One of our top picks included Blueair because of the very positive feedback and extensive use. My colleague has multiple sizes throughout the house, and highly recommended the selection. As mentioned in the review, they saw a noticeable difference in air quality after purchasing this product.

Functionality

When pulling together our best-selling list of air purifiers, we were looking at a few different performance criteria: multi-option filtration, CADR metrics and square footage, smart home or touchscreen features, and filter lifespan. We also visited AHAM Verifide and EnergyStar.gov to cross check performance claims when applicable.

Price

We love a good deal, but when it comes to your health, sometimes the age-old adage "you get what you pay for" is all too true. We wanted to keep our picks below $300 while still providing valuable performance.

Reviews

We let the reviewers speak for themselves when it comes to hands-on testing. We strive to highlight the pros and cons of each product based on user feedback and the feature list. If a product has few (or no) verified reviewers, or the complaints outweigh the purpose and price of the product, we won't feature it in our lists.

Prices are accurate and items in stock at publish.

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