What Is an Air Ionizer? 

Updated
Categories Air Purification
What you need to know about air ionizers.

If you’re looking to improve the quality of your indoor air, you’ve surely considered an air purifier. These devices are highly effective at reducing and removing common pollutants such as pollen and dust.

There are a wide range of choices on the market, including ionizers. Ionizers work differently compared to the traditional HEPA filter, but are they any better? In fact, there have been some controversies regarding this method of air cleaning.


What Is an Air Ionizer?

Air ionizers are also commonly known as ionic filtration or ion generators. They work by emitting negative ions into the room, which bind to positive ions such as dust.

Unlike regular air purifiers — which use a fan to draw air in — ionizers only emit a cloud of negative ions. Now, there are actually two common types of ionizers: Electrostatic precipitators and ion generators. Let’s take a closer look.

Electrostatic Precipitators

Electrostatic precipitators are often sold as standalone units; these don’t have a fan to draw air in. They disperse ions through corona discharge. This is an electrical discharge caused by the ionization of a fluid. The negative ions then bind to particles in the air and are collected on an oppositely-charged flat plate (1).

After, the collection plate is easily removed and wiped clean. This method is popular because you get to see the unit in action. Electrostatic precipitators are also generally more affordable compared to ion generators and air purifiers.

Ion Generator

Ion generators are more versatile and can be found as standalone units. They may also be a built-in feature of regular air purifiers.

These ionizers produce ions via UV lights or corona discharge. Unlike precipitators though, many ion generators do not use a collecting plate.

So when ion generators are a feature on a filter air purifier, it most often doesn’t have a collecting plate. Manufacturers often draw customers in on this basis as you won’t have to deal with a plate.

Since there is no place for the pollutants to be collected, where do they go? This is where ion generators fall flat. Once the negative ions have bound to the particles, they become too heavy to float in the air.

When the particles can’t float in the air, they’ll drop to the closest oppositely-charged surface. This means you’ll end up with dust and other airborne pollutants on your bed, couch, walls, carpets and more.

Worse yet, because the pollutants now linger on other surfaces, you’ll need to clean more often.

Ozone Production

What many homeowners fail to understand is that ionizers actually produce ozone as a byproduct. Ozone is commonly known as the layer that protects us from the sun’s UV rays. However, as the EPA puts it: “Good up high, bad nearby.”

Ozone is usually formed outdoors when nitrogen oxide and volatile organic compounds react to the heat of the sun. At ground level, ozone can be harmful to our health. It can trigger a line of health problems, mainly respiratory issues. This ozone is also a main component of smog, which covers many large cities across the globe (2).

Indoors, ozone is produced by air ionizers (if you have one in your home). As we mentioned above, ionizers commonly use corona discharge to emit negative ions. However, the gas emitted by corona discharge can be toxic to humans and the environment (3).

You may wonder how these products are still being sold. Regulations have been put in place. Despite this, however, many manufacturers fail to warn their customers of the potential side effects of ozone.

Consumer Reports tested five of the most popular ionizers on the market. The magazine found that the devices produced more than 50 parts per billion (ppb) of ozone. Any ozone exposure of over 50 ppb is considered moderately concerning, especially for children, the elderly and individuals with asthma (4).

How to Protect Yourself and Your Family

If you do want to purchase an ionizer, there are a few points to keep in mind. Some manufacturers work hard at producing ionizers with a limited ozone emission. You can even find air purifiers with an ionizing feature that does not produce ozone.

However, you should steer clear of any product where ozone isn’t mentioned in the description. These manufacturers are more likely to be hiding the truth due to fear of loss in sales.

We highly suggest that you look for CARB-certified air purifiers with an ionizing feature. Being certified by the California Air Resources Board, you can be sure that the unit only produces small amounts of ozone. For an ionizer to be CARB certified, it has to meet the limit of 0.050 parts per billion of ozone emission (5).

How Effective Are Air Ionizers?

How effective an air ionizer is depends on the type. Units with a collecting plate are more effective compared to those without. This is because they collect pollutants, whereas devices without collectors can leave a mess behind.

When your device doesn’t have a collecting plate, the effectiveness is actually dependent on you.

If you fail to clean your house or area surrounding the ionizer, you might not notice any difference. But when the heavy particles are stirred — maybe you sit down on the couch or someone jumps on the bed — the pollutants are then reintroduced into the air.

Some high-end air ionizers available can cover large areas of up to 2,000 square feet. However, most are only able to cover up to 600 square feet.

Air Purifier vs. Air Ionizer

The main difference between air purifiers and air ionizers is how they remove impurities from the air. However, there are also other ways the two air cleaners differ:

Filter vs. No Filter

Air purifiers are generally fitted with a HEPA filter. These range in quality from HEPA-type to true HEPA. Filtered devices utilize a small motor that sucks air in, which passes through different filters. How many filters a device has is usually disclosed as filtration stages, such as two-stage or three-stage.

Along with the HEPA filter, you’ll likely find an activated carbon filter. This filter absorbs odors as well as gases such as VOCs.

Once the air has passed the filters, it’s then dispersed back into the air. Some devices will do this from the back, top or all around the sides. You often get smart features such as an auto mode that monitors the air and then adjusts the fan accordingly.

Ionizers, on the other hand, send out electrically charged ions that bind to pollutants in the air. The pollutants are then either collected by an oppositely-charged plate or left on any surface within the room.

Room Coverage

Filtered air purifiers are most effective at cleaning an area of up to 1,000 square feet, some covering more. However, this depends on the size of the unit, so you must always check the description.

In comparison, air ionizers can cover large areas over 2,000 square feet. However, there’s a limited choice available, and these tend to be more expensive. Most air ionizers are intended for rooms of up to 600 square feet.

Cost and Maintenance

Air purifiers aren’t cheap investments. Still, there are budget options available. However, due to the additional filters and features, filtered air purifiers are more expensive than ionizers.

Filtered air purifiers are also more expensive to maintain. The filters require regular replacement for the device to work effectively. This is often done every six to 12 months — some air purifiers feature washable or reusable filters.

In comparison, because ionizers don’t have any filters, there’s nothing to replace. The only maintenance you’ll be doing is wiping the collecting plate (if applicable). If there’s no plate, you’ll simply be sweeping and dusting the house more often.

Design Options

Ionizers have a very limited style, with most being slim and vertical in design. Most ionizers are also compact and made to stand in corners or any other location out of sight.

Filtered air purifiers, on the other hand, come in a range of sizes and shapes. The size is usually related to the unit’s room coverage. Smaller units are designed for smaller rooms such as offices and nurseries.

Should You Buy an Air Ionizer?

Whether or not you should buy an ionizer is a personal choice. However, considering the risks and all of the points mentioned above, we don’t recommend it for everyone.

Not only is there a risk of ozone being emitted into your living area, but they’re also not as effective as filtered units. Unless the ionizer features a collecting plate, you’ll be left with dusty surfaces that require additional cleaning.

Despite ionizers being recommended to asthmatic individuals by manufacturers, experts advise otherwise. In fact, due to the production of ozone, the device is more likely to cause irritation, symptoms and attacks than the pollution itself.

You can find filtered air purifiers with an optional ionizer; these usually don’t produce any significant amount of ozone. However, the ionizing feature also isn’t as effective as an actual ionizer. These features are sometimes added to an air purifier simply to justify a higher cost.

Frequently Asked Questions

Does an Ionizer Remove Odors?

Ionizers are not effective at removing odors. The negatively charged ions that the device emits will bind to larger molecules in the air, such as dust and pollen. However, it will leave most odor-causing molecules behind.

If you have trouble with unpleasant odors in your home, we highly recommend an air purifier with an activated carbon filter. The activated carbon will absorb odors as well as gases.

Are Air Ionizers Bad for Health?

Whether or not an ionizer is bad for your health depends on a few factors. First, the production of ozone, a harmful byproduct. Although this is in relatively small amounts in some cases, it’s still introduced to your home.

Ionizers have also proven to worsen allergies and asthma in some cases. Not only does the ozone become a lung irritant, but allergens and dust left behind can trigger symptoms (6).


Air Ionizers 101

Air ionizers have been on the market for decades, despite the fact that they produce ozone as a byproduct. There are two main types of ionizers, the most popular being the electrostatic precipitator. This type utilizes a collecting plate that collects air pollutants.

However, more often than not, pollutants are left lingering on the nearest surface. This causes allergens and contaminants to continue to affect us as we inhale the particles.

We generally do not recommend ionizers, but if you choose to purchase a unit, ensure it’s certified. Look for low-zone emissions in the description and potentially a CARB certification.

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About the Author

Matthew Sullivan

Matthew is a freelance writer with several years of experience in DIY and HVAC. For as long as he can remember, Matthew has always found great pleasure in taking things apart and learning how to put them back together.
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