Air ionizers vs. air purifiers, which should you buy?

What's the difference between air ionizers and air purifiers?

When you want to make the air in your home cleaner, you can opt for an air ionizer or air purifier. An air ionizer is a type of air purifier. Still, in this article, the term "air purifier" refers to HEPA air purifiers and the term "air ionizer" refers to ionic air purifiers.

Air ionizers use negatively charged ions that transfer their charges to air pollutant particles in the environment, causing them to stick together and eventually fall to the floor. They can then be vacuumed up. Air purifiers use a fan to suck air into the room into them and physical filtration to trap pollutant particles.

Air ionizers

An air ionizer is a type of air purifier that removes pollutant particles — such as dust, pollen and pet dander — from the air by releasing negatively charged ions. These ions impart their negative charge to airborne particles, causing them to stick together. 

Once enough pollutant particles have stuck together, they become too heavy to remain in the air and fall to the floor, where they'll be picked up the next time you vacuum. Some models feature oppositely charged plates to attract these particles when they pass through the ionizer air purifier.

Ionizers tend to be cheaper than HEPA air purifiers covering similar square footage, which is a plus if you're on a tight budget.

Air ionizer pros

• Large coverage area: Air ionizers tend to have larger coverage areas than HEPA air purifiers. The most powerful ionizers can clean air in rooms up to 3,000 square feet, whereas powerful HEPA purifiers tackle just half that area.
• No filters to clean or replace: Because they don't use physical filters, you don't have the cost or maintenance of replacing or cleaning filters. 
• Affordably priced: Ionizer air purifiers tend to be more affordable than their HEPA counterparts, especially when you consider the size of the spaces they can cover. 
• Tackles fine particles: While HEPA filters trap 99.97% of particles up to 0.3 microns in diameter, ionizers take on particles down to 0.1 microns in diameter. However, there is the risk that these particles can get stirred back up into the air as you move around the house and go about your business. 
• Some combine ionic technology with HEPA filtration: You can find some ionizers that also contain mechanical filters. This gives you the benefit of them trapping some particles along with the other pros of ionizers.

Air ionizer cons

• Potential air pollutant: Some air ionizers emit ozone, which is considered an air pollutant, so you might get rid of some pollutants in your air but gain others.
• Don't trap pollutants: Air ionizers don't trap particle pollutants; they just get them to drop out of the air. This means that all the polluting particles will drop to the floor or onto flat surfaces, like mantels and counters, and stay there until you clean them. 

Best air ionizers

Ivation 5-in-1 Air Purifier

This multipurpose air ionizer uses ionic technology to purify the air and features a HEPA filter to mechanically filter out and trap tiny particles that a standard ionizer might miss. It also has a carbon filter, which helps it remove odors from the air, such as those caused by pets or smoke. It's great for large areas of up to 3,700 square feet.

Sold by Amazon

Envion Ionic Pro 500 Square Foot Ionic Air Purifier

This nifty ionizer air purifier can clean the whole air volume in a medium or a large room of up to 500 square feet as many as three times in an hour. It combines HEPA filtration with ionic technology to cover all the bases.

Sold by Amazon

InvisiClean Claro Air Purifier

Although it also contains a HEPA filter, this purifier uses ionic technology to tackle fine particles. As an ionizer air purifier, it's great for large spaces of up to 1,500 square feet. It has a real-time air quality monitor to keep you apprised of the condition of air in your home.

Sold by Amazon

Clarifion Air Ionizers for Home

You get three ionizer air purifiers in this pack. Each Clarifion air ionizer is extremely compact and easy to install and use. Just plug your Clarifon air ionizer into an outlet and it takes up a similar amount of space as a plug-in air freshener. The Clarifon air ionizer is whisper-quiet and doesn't take up any floor space or counter space. 

Sold by Amazon

Holmes True HEPA Allergen Remover Mini Tower Air Purifier with Optional Ionizer

Combining HEPA filtration with air ionizing technology, you get the benefits of both types of air purifiers. It's ideal for relatively compact spaces of up to 80 square feet. It's a great air purifier under $100.

Sold by Amazon

Air ionizer FAQ

What are the benefits of ionized air?

A. Ionizers remove particles, microbes and odors from the air. This makes the air healthier to breathe and feel fresher. They're of particular benefit to people who suffer from allergies and asthma, since they remove allergens from the air, as well as particles that can exacerbate asthma. Ionizers that release ozone can also kill or prevent the growth of viruses, meaning you may get sick less often. 

Do air ionizers really work?

A. Yes, ionizers work, but you should know what to expect as they may not do everything you expect them to do. While they remove particles from the air, they don't entirely get rid of them — these particles stick together until they get heavy enough to fall to the floor. So you'll only truly remove them from the room when you vacuum and clean surfaces like tables and counters. 

Air purifiers

Air purifiers use HEPA filtration systems to remove and trap airborne particles. HEPA filters can trap at least 99.97% of all particles down to the size of 0.3 microns. 

This includes mold spores, pollen, dust, bacteria and viruses. HEPA air purifiers are ideal for anyone who suffers from environmental allergies, such as hay fever or dust allergies. You can find some basic air purifiers for around $50, but you'll pay at least $100-$200 for a quality model. Top-end HEPA air purifiers can cost more than $1,000.

Air purifier pros

• Trap and contain allergens: Air purifiers trap allergens and other pollutant particles in the air, so they won't stick to your home surfaces or be able to re-enter the air.
• Great for people with asthma and allergies: Air purifiers are great at removing pollen, dust, dander and other substances that can exacerbate allergies and asthma. Unlike ionizers, they trap them so they can't be stirred back up and cause problems. 
• Trap mold particles: If you're worried about the effect of mold in your home, you'll be pleased to know that this type of purifier traps mold spores. 
• Don't negatively affect air quality: HEPA air purifiers don't emit ozone, unlike most air ionizers, so you don't need to worry about them affecting your air quality.
• Some have washable filters: You can buy air purifiers with washable filters, so there's no need to spend money on replacement filters.
• Can trap some finer particles: To be classed as a HEPA air purifier, its filter must trap 99.97% of particles up to 0.3 microns in diameter. However, this doesn't mean that they don't trap a decent amount of particles smaller than this — just not necessarily as large a percent. 

Air purifier cons

• There's some filter maintenance involved: You'll need to either buy new filters to replace old ones or clean the filters and replace them, depending on your chosen model.
• Small coverage area: Air purifiers tend to cover a smaller area compared to air ionizers.
• Not able to remove odors: HEPA air purifiers can't remove odors or chemicals from the air unless they also incorporate an additional activated carbon filter.

Best air purifiers

Dyson Pure Cool Link 

Not only is this an effective air purifier that's suitable for large rooms, but it also looks like a piece of modern art, so it won't detract from the appearance of your room. It can also act as a fan to cool you in warm weather and this model is Wi-Fi enabled so you can control it via an app or using Amazon Alexa.

Sold by Amazon

Levoit Air Purifier for Small Space

If you want to clean the air in a small space, this Levoit air purifier is an excellent choice. It's a great air purifier under $50, proving you don't have to spend a fortune to get a decent model. Levoit air purifiers are well-known and reliable, making them ideal for people searching for trustworthy models. Anyone who's looking for a Levoit air purifier on a budget should consider this option.

Sold by Amazon

Alen BreatheSmart FLEX HEPA Air Purifier

This high-end HEPA air purifier runs quietly and cleans the air in spaces up to an impressive 900 square feet. You can choose from several different versions, including a model that specializes in pet odor and dander and another that's great for allergies and dust.

Sold by Home Depot and Amazon

Levoit Air Purifier for Large Room

You don't need to look further than this Levoit air purifier to find a smart air purifier that's Wi-Fi-compatible. You can control it with an app or as part of a smart home system. It can eliminate odors, allergens and other physical particles.

Sold by Amazon

Honeywell True HEPA200 Air Purifier

This reliable HEPA air purifier comes from a reputable brand and is suitable for rooms up to a suggested size of 310 square feet. In a room of this size, it circulates the full air volume every 12 1/2 minutes, so you're always breathing fresh air. 

Sold by Home Depot and Amazon

Levoit Air Purifier H13 True HEPA Filter

As a true HEPA model, this Levoit air purifier doesn't emit ozone and can trap particles such as pollen, pet dander and mold spores. It runs quietly and is perfect for rooms of up to 300 square feet. If you're looking for an energy-efficient option, this Levoit air purifier is extremely cheap to run.

Sold by Amazon

Air purifier FAQ

What are air purifiers good for?

A. Air purifiers are good for trapping and eliminating particles from the air, including pollen, pet dander and dust. They trap the particles in their filters, where you can wash them down the sink by cleaning the filter. They're good for improving air quality and limiting the allergens in the air, which can help people with allergies and respiratory issues. 

Should I sleep with an air purifier on?

A. Whether you want to sleep with an air purifier on is up to you, but it's safe to do so. It may also improve your nighttime breathing, helping you to sleep better. 

Should you get an air ionizer or an air purifier?

Objectively, HEPA air purifiers do a better job of cleaning the air and trapping pollutant particles than ionic air purifiers. They don't emit ozone and they don't cause particles to drop and remain in your home until you clean them up. Therefore, an air purifier is usually the better choice over an air ionizer, especially if you have allergies. 

However, you might consider an air ionizer if you need to clean the air in a large space on a low budget. Air ionizers are also great if you don't like the idea of cleaning filters or having an ongoing cost to replace them. Some are also great for small spaces due to their compact size, such as the Clarifon air ionizer. 

It's up to you which to buy, but for most people, a HEPA air purifier makes the most sense. This is particularly true if you opt for a trusted brand, such as a Levoit air purifier or a Dyson air purifier. 

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Lauren Corona writes for BestReviews. BestReviews has helped millions of consumers simplify their purchasing decisions, saving them time and money.