Ionization and Air Purifiers

air purifier ionization

Ionization, when it comes to air purifiers, can be implemented in two different ways:

  • as the only or primary means for air purification
  • as an additional and/or optional means for air purification

We do not recommend any air purifiers that use ionization as the only means of air purification (we go over the reasons why later). We do, however, recommend air purifiers that use an ionizer as an additional and optional means for air purification.

Sometimes it’s an additional but non-optional feature. We do not recommend such air purifiers either.

Benefits of Ionization

When an ionizer is an optional component of an air purifier it usually works like this:

  • air is pulled into the air purifier and flows through an “ionization field” of some sort
  • some of the atoms/molecules comprising the air are electrically charged by the ionization field. The electrically (normally negatively) charged atoms/molecules are called ions
  • the ions are emitted out of the air purifier along with the rest of the exhaust air

These ions provide several benefits:

1. Increase effective particle size

The electrically charged ions can either attach to particles themselves or impart their charge to particles. The charged particles can then attract other particles. The end result is that particles become larger – whether by adding on ions or by clumping up with other particles.

This, in turn does two things

improves the efficiency of particle filtration

Larger particles are easier to filter. Instead of having to filter a large number of smaller more difficult to filter particles the air purifier is now able to filter a greater number of larger easier to filter particles.

Larger particles also fall to the ground faster – a greater number of particles are closer to the ground. This enables the air purifier to more easily intake “dirty” air. Remember, an air purifier sits on the ground. It’s a good thing for particles to be weighed down so that they’re closer to the ground where the air purifier can take them in to process them.

effectively lowers airborne particle concentration in the room – no filtration required

Again, larger particles fall to the ground faster. If they stay airborne they will absolutely get filtered but if they fall all the way to the ground that’s just as good in terms of keeping them out of your respiratory system – in other words, in terms of keeping you from inhaling them. Once the particles are on the floor you can vacuum them, mop them up, etc. Either way you can’t inhale them if they’re on the ground.

2. Deodorization

Some of the ions released by an air purifier do not attach to particles. These ions can have certain benefits themselves.

Ions are

  • odorless and tasteless
  • naturally occurring in the air near bodies of water – e.g. mountain streams, waterfalls, and the ocean

It’s not surprising then that air with a high concentration of ions smells fresh and odorless.

An air purifier with ionization turned on reduces odors in two ways

  • by reducing the concentration of foul smelling molecules by filtering them out via a carbon filter
  • and now, with ionization turned on, by reducing the concentration of foul smelling molecules by increasing the concentration of odorless molecules - ions

3. Other benefits including the potential to kill bacteria, alleviate depression, etc.

Certain studies have shown that ions can be bactericidal – ie. kill bacteria. While it’s not necessary to kill bacteria in order to filter them out of the air (whether it’s dead or alive bacteria is essentially the same as any other particle for an air filter), this is still a positive for ionization.

Breathing in ions can also possibly have certain health benefits like improving happiness, alleviating depression, and just generally making you feel better. That being said, studies for such claims have so far been inconclusive .

The one major downside of ionization

Whether they’re absolutely true or only a possibility, these are all good things – increasing effective particle size, deodorization, killing bacteria, etc.). So why would you not want ionization?

The answer: Ozone.

The one major negative of ionization is that it generates ozone. And ozone is not good for you.

The good news is that most air purifiers on the market that ionize air do NOT produce a large enough quantity of ozone to be harmful to your health. How can we be so sure?

The state of California has legislated that any air purifier sold in the state must be certified by the California Air Resources Board (CARB) to produce no more than 0.050 parts per million (ppm) of ozone. Most air purifiers on the market and all units we recommend have been certified.

Our Recommendation

Ionization is a great optional feature to have but it should never be used as a differentiating factor when it comes to making an air purifier purchase. Energy efficiency, noise output, durability, value, and especially filter type and CFM how much air the unit can process in a given amount of time) – these are all much more important factors to consider.

The air purifiers we recommend use filters to lower particle filtration in a room. These filters work and they work well. An ionizer can certainly help with the process but most of the work will still be done by the filters. As long as an air purifier is equipped with a HEPA filter and adequate CFM it will be able to lower particle concentration in a room.

Top rated units all are equipped with HEPA filters and all have sufficient CFM to properly lower particle concentration in rooms up to 300 sq. ft. For larger rooms we recommend multiple top rated units.

Ionizers We Don’t Recommend

Two Implementations of Ionizers

Recall that there’s only two ways to implement an ionizer. So far we’ve only looked at one implementation – in which it’s an add-on component of air purifiers that use filters as the primary means to lower particle concentration in a room.

Ionizers can also be implemented as the only means for particle reduction.

Three Different Types of Ionizers

While there are only two different implementations, there are three different types of ionizers on the market. The first two types can be implemented as either stand-alone or add-on ionizers. The third type is only implemented as a stand-alone ionizer. That third type is the type with the subsequent implementation that we don’t recommend.

Three types:

Negative ionizers

these ionizers only emit negative ions. They can be implemented as stand-alone units but are mostly integrated with filter based air purifiers.

Example units: stand-alone - IonPacific ionbox, integrated - Blue Pure 211+

Dual polarity ionizers

these ionizers emit both negative and positive ions. They are mostly integrated with filter based units.

Example units: Winix 5500-2 Plasmawave.

Electrostatic Precipitators (ESPs)

ESPs impart an electric charge directly to particles and instead of relying on a filter for capturing the charged particles, ESPs use oppositely charged metal plates to do the capturing and collecting of the particles.

Example unit: Ionic Pro 90IP01TA01W Turbo Ionic Air Purifier

ESPs are the most common type of ionizer that implements ionization as the primary means for particle reduction. This is also the type of ionizer that is commonly called simply an “ionizer” or an “ionic air purifier”.

Earlier we noted that we do not recommend units that use ionization as the primary means for particle reduction. Here are all the reasons why:

Fanless design

Ionic air purifiers usually* don’t have fans. Consumers are attracted to this feature because they think that fans are bad. Fans break. Fans make noise. These are all bad things. So fanless must be better than not fanless.

Here’s the thing. Fans on top rated durable units do not break and do not make an unpleasant noise (they make a pleasant sounding “white noise”). On lower fan speeds, the noise is often imperceptible.

*Note: some ionic units do have a fan but the most popular units do not.

Filterless design

ESPs (which are what most ionic air purifiers are) use charged plates to collect dust and other particles.

These plates “saturate” with particles much quicker than HEPA filters.

Collector plates have a flat surface – what you see is what you get in terms of surface area. HEPA filters are pleated with millions of microscopic fibers - there’s a ton of surface area invisible to the naked eye. As particles collect on these plates and filters they take up space.

The more space available – the more surface area – the longer it takes before the space has to be “renewed”.

Collector plates need to be wiped down while HEPA filters need to be replaced. The former option is free but requires frequent maintenance. The latter option costs money but requires much less frequent maintenance.

In addition, collector plates lose efficacy as particles build up. HEPA filters do not. They actually become more effective in trapping particles as they saturate.

Ozone generation

Ionic air purifiers generate ozone as a byproduct. Units sold today meet government regulations. However, these regulations don’t take into account using the air purifier in

  • especially small spaces
  • poorly ventilated spaces

If you use an air purifier with an optional ionizer you can simply keep it off if you need to use the unit in such a space. However, if you use a unit that uses ionization as the primary or only means of air purification, it’s impossible to turn it off and therefore impossible to use in such a space. If you do use such a unit in such a space you could be putting yourself at risk.

The Bottom Line

Ionization does work. And can be quite helpful. But, it should never be the primary or only means of air purification.

And when it’s implemented as an add-on feature it should always be optional so that you can turn it off when using the air purifier in a smaller room or a room with poor ventilation.

Rest assured, all top rated units either do not feature an ionizer or feature an ionizer that can be turned on or off.

Add a Comment

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Comments (2)

Ethan D Moultonsays...

Thank you very much. Your explanation has really helped in understanding this technology. So much more than what I have been reading.

I am a dentist and have been researching how to best clean the air in my office with various technologies. Your reviews seem to be the most informative/educational and the least biased of all that I have read/watched.

I have been considering re-doing much of my HVAC ducting to bring in more fresh air and create negative pressure and adding Airscrubbers to my HVAC system. Air Scrubber by Aerus (this sounds like the 3rd type of ionizer from what you discuss)?:)

Would you think the Winix 5500-2 would be suitable/sufficient for in the dental room use? room sizes 10x8x8

Thanks for your insight, Ethan Moulton

Consumer Analysissays...

It's difficult to say without directly looking at your office space and evaluating all of the variables involved. That being said, I'm leaning toward your idea of bringing in more fresh air with negative air pressure and adding a heavy duty air cleaner like the Air Scrubber over using individual residential air purifiers (like the Winix) for a commercial application.


When is a bedroom a small poor ventilated room? Can a ioniser be used in a bedroom 150 sq feet large overnight, previously ventilated but with the windows closed overnight?

Consumer Analysissays...

It's difficult to say without testing the ozone generation and build up in your particular space with your particular ionizer. That being said, we had a space smaller than 150 sq. ft. in mind when talking about "especially small spaces" in this guide. We had a space with no working HVAC system and one that is fully sealed (windows and doors closed) in mind when talking about a "poorly ventilated" space in the same guide.