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Air Ionizer Dangers: Are Ionic Air Purifiers Safe?

Derek Hales

Written By: Derek Hales

Updated on:

Air ionizers are designed to help provide cleaner air and they do this by utilizing ionized particles. But a lot of questions tend to come with the use of air ionizers, one of the most common being…Are air ionizers dangerous?

The Short Answer: It depends on who you ask. Some critics believe that air ionizers give off dangerous levels of ozone which is not only harmful to the environment, but can be equally as hazardous to your health.

air ionizer dangers - air quality
Ozone exists in 2 levels of the atmosphere: in the stratosphere (good – protects us from the sun’s rays) and at the ground level (bad – toxic when breathed in)

When inhaled in high enough doses, ozone can have harmful effects– including damage to your lungs, chest pain, coughing, or shortness of breath.

Because of this concern, federally-mandated standards restrict the amount of ozone any air purifier can give off. These restrictions help to ensure that any potential ozone exposure remains at a safe level.

Air ionizers vs. Ionic air purifiers

First things first, let’s get our names straight. In the air purifier market, there are air ionizers and there are ionic air purifiers.

Rabbit Air Purifier Filters
The Rabbit Air MinusA2 uses 5 different filters and an ionizer as the last purification stage

What’s the difference?

Basically nothing.

These are two different ways to talk about the same technology, electrically charged molecules being used to help purify the air. In this guide, we’ll be calling them air ionizers– so let’s continue.

How do air ionizers work?

A typical air purifier would use fans or filters to help remove contaminants and purify the air. In the case of air ionizers, they rely on the use of electrically charged air molecules, or ions, to do the same job.

RELATED – See our full list of air purifier reviews.

Every room is filled with positively charged particles, which could be made up of dust, microbes, odors, airborne bacteria or illnesses, smoke or other allergens.

The job of an air ionizer is to release negatively charged particles that are then attracted and bond to the positively charged particles in the room.

how air ionizers work

When the ionized particles bond to the airborne particles, the joint union is then too heavy to float in the air and they fall to the ground. Once they’re no longer airborne, these particles can be vacuumed up, or dusted off of furniture and raised surfaces.

What are the benefits of air ionizers?

Negative ions produce a number of benefits in our natural environment.

Think of some of your favorite places. Maybe it’s the ocean, a serene waterfall or out in nature’s greenery.

Ionic particles produced by waterfalls

This short list here includes some of the natural environments with the highest levels of detected negative ions present

Air ionizers and their connection to negative ions can mean big benefits to your respiratory system and overall health. The use of negative ions in the air can have the following results:

  • Improved air quality through the removal of dust, allergens, pollen, pet dander, mold spores and other airborne bacteria.
  • Decreased exposure to airborne respiratory bacteria like colds, flu, and asthmatic triggers
  • Improved sleep and overall mood, according to a 2012 Italian study that looked at the evidence base for the benefits of negative ions in improving mood and treating mood disorders
  • Relief from seasonal or chronic depression— according to a study from Columbia University, negative ions can have as much of an effect as prescribed antidepressants

All this sound too good to be true?

Some people would say yes. Let’s talk about the potential negative side of negative ions.

What are the dangers of air ionizers?

So naturally occurring negative ions are highly beneficial and share all of the benefits listed above. In the case of air ionizers, these negative ions aren’t naturally occuring, but instead are created through a method called “electric-discharge”.

air ionizer dangers - air quality

During the process of electric discharge, the negative ions that are produced may give off ozone, which can be a very harmful and toxic gas.

What is ozone?

Ozone is a colorless gas that exists in two levels of our atmosphere– one is good and one can be not so good.

air ionizer dangers - oxygen vs. ozone
Oxygen has 2 oxygen atoms while ozone is made up of 3 oxygen atoms, making it toxic for humans to breathe.

On one level, it exists in the stratosphere (which is approximately 6-30 miles high) and helps to protect Earth from the sun’s harmful radiation.

On another level, it also exists at the ground level, which is the air we breathe. Ozone in this part of the atmosphere is not good.

Ever see those ozone alerts as you drive down the highway or on the nightly news?

These are generated to let you know that ozone levels at the ground level may be reaching unsafe levels.

High ozone levels in the air you’re breathing can have really nasty side effects including damage to your lungs, chest pain, coughing, or shortness of breath.

Do air ionizers emit ozone?

So the million dollar question- do air ionizers emit ozone?

In short, yes they do.

Any man-made high-energy particle, like a negatively charged ion can generate ozone as a by-product of the molecular reaction.

Anyone remember the Ionic Breeze from Sharper Image? This product was one of the first air ionizers that came out.

Initially it was widely popular, but trouble came when third-party review sites began to question not only the validity of the air purification system, but also the dangerous levels of ozone that it was emitting.

SHarper Image Ionic Breeze air ionizer advertisement -1999 - source: The Hustle

What resulted from this product was a class action lawsuit, bankruptcy for Sharper Image in 2008, and revised federally-mandated standards (under the Clean Air Act) that put limits on the amount of ozone that a machine like this could generate.

Under these new regulations, the US Food & Drug Administration (FDA) required that indoor medical devices can only produce a maximum of 50 ppb (parts per billion) of ozone.

For comparison, the National Institute of Occupational Safety and Health (HIOSH) advises that indoor ozone levels be no greater than 100 ppb.

Air ionizers today are often fitted with ozone sensors that help to monitor, suppress, and prevent high levels of ozone from sneaking out into the air you breath.

The Bottom Line

Deciding whether or not an air ionizer is right for you is a personal decision. There are certainly benefits to air ionization that be difficult to achieve with a standard air purifier, but with those benefits also come potential risks.

Ozone is a real threat to our health, when consumed in high levels, but today’s air ionizers are federally-restricted in the amount of ozone that can be produced as a by-product of these machines.

At the end of the day, you have to decide for yourself and your family if the benefit of ionized air outweighs the potential risk of increased ozone levels.

Do your research, understand the technology, and move forward into a home with cleaner air.

More Resources

About Derek Hales

Derek HalesDerek Hales is the Founder and Editor-in-Chief of He has been featured in Fast Company, Reader's Digest, Business Insider,, She Knows, and other major publications. Derek has a Bachelor's Degree in Business Administration from Kansas State University. Hales has been testing and reviewing products for the home since 2014.

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249 Comments on “Air Ionizer Dangers: Are Ionic Air Purifiers Safe?”

  1. Hi Derek ;
    First of all, it’s a good research article. So what do you think of the Xiaomi Smart Air Purifier Pro 4? (a product with negative air ionization)
    Does this product have an ozone emission problem?

  2. Derek,
    Great article. Just a little warning to you and your readers. It seems reasonable to think air purifier manufacturers would not risk losing their business by lying to customers. So I understand why you deduce that they can be trusted when they say things like “our product doesn’t emit unsafe levels of ozone.”

    But when our business ethics are overshadowed by a profit at all costs ethic, reasonable goes out the door.

    The historical evidence in terms of harmful products and what companies do to avoid liability suggests just the opposite. Many companies make false claims.

    What has occurred in my lifetime (in my mid 50s) is that regulators have become increasingly influenced (or paid off) by corporate lobbyists
    and unless and until very expensive class action lawsuits emerge—the lies companies tell are endless. Consider the corruption in medicine that has occurred by when pharma started courting doctors to promote their drugs to patients who don’t actually need those drugs.

    I would recommend that your readers who are concerned about manufacturer claims find a qualified expert to test the purifier or refer to independent expert reviews of the product. Having someone come and test the purifier in one’s home to see if ozone levels are “low enough” would be worth the cost for those who can afford it.

    I’ve experienced dozens of cases with a variety of products wherein the sales people or reps didn’t know or were themselves misinformed about their product, and reviews revealed the product was dangerous, the company was in litigation for its false claims and so on.

    Let the buyer beware.


    • That’s a very fair and reasonable belief.

      Perhaps I have been too trusting of many of these low impact ionizers.

      Suffice to say, the safest option would be to avoid any air purifier with an ionizer any of any type or any that alters the air chemistry in any way. HEPA purifiers have more than proven themselves effective over the decades and purify the air without adjusting air chemistry.

      For my best air purifiers for 2023 list I am considering adding my own in-house ozone test, to independently verify exactly how much (if any) ozone these purifiers generate.

      Thank you again for your thoughtful and well reasoned comment.

  3. Midland air recently put a UvplusOxidizor about two months. I am having headaches since that oxidizer has been installed. Help. I will call midland heating and air to remove it. Because they did not explain the negative side effects before they installed it. All the tech said was it’s good for mold .

    • Yep…unfortunately HVAC companies don’t understand or are willfully ignorant on the dangers of ionizers.

  4. If ionizing air conditioners and other electrical devices and appliances give off ozone and radiation emissions, and, although cleaning up the air, they cause cancer; especially, over long periods of time and frequent use; and, regardless of Federal restrictions; why are they being sold and used!?! ACWD

    • Simple answer is that they work. People who are uninformed know they work, but don’t understand the dangers. So their use continues in certain circles.

  5. We froster dogs but have 6 dogs of our own. Yes they shed some more than others and we have a lot of dust we have to clean. I’m wondering how safe it is cause we are seniors

    • Ionizers that produce significant quantities of ozone are not safe. If you’re unsure, just don’t risk it.

      It’s not safe for you, your dogs, or any living thing.

    • If it’s a small manufactured product probably only the manufacturer…if it’s a large unit, HVAC tech would be my first call to see if they can help.

  6. Hi,I bought an air purifer that has a built in anion mode,meaning it dis charges negative ions into the air. Does this release ozone? I could not tirn off the anion mode.

    • Most likely no. However, you’d need to ask the manufacturer directly for an answer to know for sure.

  7. “At the end of the day, you have to decide for yourself and your family if the benefit of ionized air outweighs the potential risk of increased ozone levels.”

    Derek Hales…based on your research, would YOU personally keep an air ionizer in YOUR home?

    • In most cases I simply turn any ionization feature off.

      On the units that have an ionizer, but say they don’t produce ozone, I have not measured any significant air quality performance difference.

      As a result, even if the increased risk of ozone exposure was low or the company was lying, it’s just better to turn it off so I don’t have to worry about.

      Standard HEPA filtration is perfectly good and that’s what I recommend.

  8. I am considering adding a RGF Clear Sky ion purification system to a new furnace/ac unit yet to be installed in my home. The furnace salesman said the RGF reps told him the unit does not produce ozone. If this is so I will probably buy it but I’m not sure I am being told the truth. I would like to hear what you have to say about it, thanks, Bill

    • I don’t know about that model specifically.

      However, if the manufacturer rep says it doesn’t that seems reasonable to believe. The penalty for lying about that would put a company out of business (as it did to Sharper imagine in the early 2000s).

  9. I wish you would have talked about bipolar ionization products like iwave that say they emit no ozone. The release equal amounts of positive and negative ions. Any thoughts on those systems?

    • Ionizers that don’t emit ozone also don’t create powerful ions, which means they just aren’t very effective. In general, I just think bipolar ionization is a marketing gimmick.

  10. Hi,

    I have a true hepa-14 filtered air purifier (380 CADR) with ionizer option. I’ve been a moderate to heavy smoker for a while. Since the conflicting data associated with ionizer is still persistent, I usually keep my ionizer option off. However, in order to get rid of my roommate’s 2nd and 3rd hand smoking hazards, now I’m planning to keep my ionizer on just for 30-40 mins when nobody is at room, and then turn off the ionizer before anybody comes inside. Aside from that, while the ionizer being switched off, does the ozone get properly filtered through air purifier?(Coz I run my purifier almost 24/7). If so, is my method of mitigating smoke hazards going to work? Or, can I take any other/addition steps in regards to minimize the hazards (other than quit smoking tomorrow)
    Also, another unrelated question, are ionizers safe for pregnant women?

    TIA for the time and relevant advice.

    • Most air purifiers are not going to be able to remove ozone. I doubt your purifier is creating any significant quantity of ozone with that ionizer, but it’s also probably not doing much for the smoke either. I would just leave it off all the time.

      Beyond that, simply leave the purifier on the highest setting you can stand 24/7 and replace the filters as needed.

  11. Are you familiar with the Homedics 5 in 1 air purifier? It has an ION mode as well as a UVC mode? Which is safer? I bought it thinking it was safe and better for my families health, now I am scared to use those modes, especially with a toddler. Is it safe to do at night with no one in the room? Should I be vacuuming immediately after to pick up the particles?

    • I’ve heard of it, but not super familiar with it. I’d just turn off the ION mode to be safe, but the UVC is perfectly safe to leave on.

      You don’t need to vacuum immediately, just vacuum on your normal schedule.

    • It’s probably safe…but only because it’s so ineffective at its job.

      Don’t buy these types of products. They aren’t worth your money.

    • You just wasted money. They don’t do anything but make the seller a millionaire off your dime. Smash it with a hammer and throw it out. It is junk.

  12. I just ordered 2 mini costway air purifiers because I’ve got asthma. Im wondering big they are safe? I haven’t received them yet and specifically asked if they were ozone producing machines and was told no. I only ordered them because they were on sale. I thought they would help while I was waiting for my IQ air to come in.

    • They don’t seem like they are producing ozone. And even if they are it’s a probably a small amount.

      Just guessing based on the product info page…to know for sure you’d need to ask the manufacturer.

  13. Hi,
    Great article. I purchased and had professionally installed IWAVE ionizer systems for my upstairs and downstairs hvac systems. Each time the heater comes on, there’s a noticeable smell with it, reminds me of what I used to get the first couple times we turn on the furnace in the winter. I know that the iWave is installed on the incoming air side of the Furnace, if it were installed on the outgoing side, would that eliminate the chance of this ionized air being cooked by the furnace? Maybe solve our IWAVE SMELL problem?

    • Not sure if you’d be able to install it in that direction. In any case, it sure sounds like you have ozone in your home. You should not have that type of strong odor.

  14. Hi,
    Thank you so much for this informative article.
    I wonder if you could advise me on the Blueair Blue 3210 Air Purifier. I thought I’d done my research before I bought it, but then read something that implied the use of an ioniser within a sealed compartment.
    This is a quote from the official blurb on the site I bought it from:
    More clean air, less noise and less energy. Blueair’s proprietary HEPASilent technology combines electrostatic and mechanical filtration to capture atleast 99.97% of all airborne particles down to 0.1 micron in size whilst the environment friendly activated carbon reduces odours and gases. Equipped with smart sensors to monitor the air quality, the Blue 3210 reacts to your home changing speeds automatically keep your air clean and healthy.

    And this is the link to what they say on their website. So, can I trust what they say? Will this air purifier be safe to use in the bedroom at night? It does seem to relieve my stuffy nose caused by various allergies.

  15. Hi there,
    Thank you for this informative article. I have recently bought a Blueair 3210 air purifier with HepaSilent filter. I bought it because I read a review that claimed it did not produce any ozone, but now I’ve read something else that says it does. The company itself claim to produce safe levels, but I’m aware that a company will always say their product is safe – is this one you are familiar with. Would it have been better to buy with with a different kind of Hepa filtration?

    • I am familiar with Blueair, but not that exact model.

      In any case, I have no reason to believe it wouldn’t be safe. Ozone standards are very clearly defined and regulated. For a respected company to claim its safe, while also creating ozone beyond safe limits, at this point in time would be just incredibly stupid.

  16. I have been looking at a lasko cyclonic ceramic heater 1500 watt with an ionizer. My husband has COPD and allergies, should we be using the ionizer?

  17. So if the unit is CARB certified (ozone emission concentration limit below 50ppb …its safe your opinion ?
    Hmmm…what if you have 2 CARB certified units in the same room ?
    I wish California Board would give the actual numbers…

  18. Hi. Are you familiar with Tylex Brand, XF22 air purifier? It is a portable prosuct that can be used in cars, rooms, etc. Does it also generate ozone? I bought it online to try if it will be effective to lessen the alergic rhinitis of my child. But i haven’t started to use it yet because of what I read online about ozone which can be harmful to health. Thank you.

    • I am not familiar with that brand.

      I did just look at their product page and nothing on this page leads me to believe it’s an ionizer or creates ozone.

      By all the info it just seems to be a small form factor HEPA filter, which is perfectly safe.

  19. Last month we had a new heating system installed. The salesman discussed adding an iwave ionizer into the unit, and gave us a discounted price, so we did it. Since the unit has been stalled, I have felt extremely tired, have slight headaches often and my head just feels weird. I was given no information about this iwave in my packet of papers, so all I have is the internet to look for answers. I remember years ago when we purchased an Edenpure air purifier, I felt this way, only worse. I’ve come to the conclusion is HAS to be the iwave causing my problems. What do you think?

    • It’s possible.

      Many of these HVAC guys don’t understand the dangers of ozone or even if what they are selling produces ozone.

      I had an HVAC tech out here 2 weeks at my house (we’re getting a new unit) trying to sell me on one of these in-duct purification units. He actually ENCOURAGED me to get the one that generated ozone because it gave it that “fresh smell”. I informed him of the dangers and that I would never get that type of a unit, but it did not deter him at all.

      You might get an air quality company to come out and check your home’s air quality.

  20. I have an old alpine ionizer. Probably 1990’s. I usually turn it on in a closed room and then turn it off before I open door to rest of house. Is it safe to use.

    • I’ve seen them, but not tested them.

      Given their size, I would be surprised if they are capable of producing dangerous levels of ozone. But by the same token…I would be surprised if they are particularly effective.

      When it comes to air purification, size matters. Bigger units almost always perform better, regardless of the technology involved.

  21. Hi Derek,

    May I ask your thoughts about using Airtamer necklace? What do you think about this?

    Please help.


    • Kind of the same thing with the Clarifon. It probably works to some level, but given the size, I am doubtful of its overall effectiveness.

      The idea that you can create a “bubble” of sorts of purified around around your person feels more than a little dubious to me. That’s just not how air works.

  22. We installed the Reme Guardian Halo for my mother for Christmas, she smokes and has emphasima. For the first month she was pleased saying ” I only used my inhaler once.” But after a few months she’s complaining of a paste like substance coating the back of her throat making it hard to swallow. Has only one else out there had this same complaint?

    • Never heard of anything like this.

      I don’t think anything the Halo is doing could have that impact. This sounds like a question for your doctor.

  23. Hi…I have a Hunter Quietflo Ultra#30736 0.8 amps from 2005…has 2 stage charcoal the hepa with ionizer ( see a small wired rod/electrode maybe 3″ long sticking out over exhaust airflow) and manual says releases negative ions into the air to attach to dust etc., which i do see clinging to wall and furniture nearby…when new I thought I could smell a certain” freshness to the air upon entering the room….the ionizer can be turned off…the manual says nothing about ozone…should i turn it off?. .it seems like sometimes ypu say better safe to keep off if manual is silent about it but recent posts say probably safe on these units due to minimal powered ionization. Appreciate your input.Thanks

  24. After using a air ionizer ,the next day i have dry cough,sore throat and slight chest pain. How lomg does it take to get relief? What can i do to get better quicke

    • Stop using that ionizer immediately. And you should consult your doctor.

      We are not medical professionals and cannot provide medical advice.

  25. Im worried about the ozone coming out of your ionizers Is your purelonic
    Ionizer have safe levels of ozone coming out of it? Is it fitted with ozone sensors that help to monitor suppress and prevent high levels of ozone from entering the air? .I just want to be sure its safe to use .Thanks for your help..

    • Unfortunately, I have never heard of that brand. I really cannot say if it’s safe or other info regarding ozone sensors.

  26. Hi Derek, thanks for your article on air ionizers/filters. I particularly appreciate your well-rounded and unbiased review of air ionizing technology and I hope I can receive a similarly unbiased concern in response to a question I have since this topic also seems to be themed in the realm of controversy.

    But it was only a matter of time before this question arose:
    Do air ionizers have any effect (good or bad) on 5G WiFi microwave radiation?
    I ask this with legitimate concern due to the recent discovery that all of the sources which told us specifically that “there’s never been any evidence to show that 5G WiFi is harmful.” -specifically said it that way because *there’s never been any studies funded by the network companies to test to see if there was any risk to health due to 5G WiFi radiation* to begin with.

    Of course there have been studies that were not funded by the network companies – independent research, just like we would presume would be standard for a company to refer to the data of as a third-party independent research data in theory provides unbiased review. In the case of these network companies, ZERO review was considered the ideal.

    If we were to save time in presumption we could rightfully presume that zero company expenditure into the study for possible health risk was allocated precisely because all of the existing research showed that 5G WiFi was dangerous and so in the spirit of Occam’s Razor if we were to presume that all of the pre-existing studies and peer reviewed science papers published in medical health and science journals is correct, and 5G WiFi is dangerous and having a negative effect on us, what effect -if any- might an air ionizer have upon the local home environment’s safety?

    I am not a educated scientist nor educated electrical engineer so I do realize I may be just ignorantly trying to connect two different and possibly completely unrelated worlds in electromagnetism. All I know is that 5G WiFi radiation is EMF and (now understood thanks to learning from your article) – air ionizers emit negative ions. Do these two things have an effect on one another?

    I’d love to hear your thoughts on the matter and I appreciate you taking the time to read this possibly-ridiculous question and I hope to get your take on it!

    • I wish I had a better answer, but unfortunately, I don’t know.

      Ionizers are dangerous because they can create ozone. But it’s not the ionic particles that are dangerous, it’s the byproduct of creating them…the ozone.

      If 5G is creating ozone at scale in confined spaces then yes, it could be dangerous for the same reason. But I don’t believe 5G creates any ozone.

      As far as interact beyond that, it is unfortunately beyond my knowledge.

  27. Please just ignore the previous comment, the f5 much time but not see the question post yet.

    1 & 2, It is will damage the environment? if you try to release the ozone from the home to outside, just thinking that may not a good situation. I just thinking is, kill the ozone, for health and environment will be both well, but how to kill the ozone, that is my question. many thanks

  28. Hi Derek, Let me clarify my question, sorry my english not good.

    Refer to your answer.

    1) Air ionizer will generate the ozone, it would be stay in your home always? that could damage human and earth. (so have Q2)
    2) How to eliminate or kill the ozone.
    4) If the ionizer really generate ozone and can not be remove, that is the argument why we use it.

    • Thanks for the clarification.

      1) The ozone will gradually dissipate over time. If you can open windows and doors that helps.
      2) Best way is to simply air out your home. Open up doors and windows.
      4) People use them because they can be effective at reducing odors and eliminating airborne particulates, but they don’t properly account for the dangers

  29. How do you check to see if a air purifier is toxic. I purchased Clairifon purifiers, (10 of the small plug in ones. My breathing became very labored. I was extremely short of breath. I took them all out and got better.

    • Email the company and ask them the quantity of ozone generated. If it exceeds 0.05 PPM then it’s not safe (based on EPA guidelines).

  30. Hi Derek, I have many questions.
    could you definition of best ways of applications of ionizers?
    air ionizer can generate ozone, can ozone minimize or eliminate?
    what are the technologies and material applied in air ionizer?
    do any unknown issues what you think?

    I just confuse about air ionizer logic. Thank you

    • I’m not 100% sure what every question is asking (a bit lost in translation), but I’ll do my best to answer:

      1) Ionizers are best used in places where you don’t have people around. So if you go to work for 8 hours during the day you could run an ionizer for a few hours and then turn it off before you get home, this way there is no ozone in the area by the time people are back in that area. Of course, the amount of ozone generated really varies by ionizer. Many ionizers just don’t generate high powered ions and are generally safe to run with people around. However, dedicated ozone air purifiers are not safe at any level to have humans around when they are running and can take several hours (or even days) to fully air out.

      2) I’m not sure what you’re asking with this question. Ionizers do generate ozone. Ozone is safe in very small quantities. Ozone will eliminate smells.

      3) Essentially, the machine creates positively charged ionic particles. These particles stick to negatively charged particles in the air, causing them to fall to the ground. The technology is a bit different for each company, but it all basically does the same thing.

      4) The biggest unknown issue is the true effectiveness of ionic air purifiers that generate low powered ions. In my view, I don’t see how these can be effective. What makes an ozone air purifier effective is high energy ions, which create ozone as a by product. Without those high energy ions they cannot be effective, in my view.

  31. Hi! Hope all is well. Wondering about the AirSoap from PhoneSoap. Seems legit and they claim to creat very minimal, I think under 10bbp, of ozone with their Electric Windt tech or something. What’s your take on it? I have the AirSoap and the Conway Mighty

  32. Hi Derek,
    I am a bus driver that drive 8-10 hours daily, and concern with the nitrogen oxides, carbon monoxide, and other pollution. Also I have very bad allergy when outdoor with pollen of grasses and weeds triggered by summer (sunny weather) allergies. I consider buying AirTamer Advanced Rechargeable Air Purifier A315 Portable Negative Ion Generator. Per their website Q&A on Ozone,

    We at AirTamer® are sensitive to the fact that cleaning the air should not produce unsatisfactory levels of ozone, so we test for ozone emission. AirTamer® produces no measurable amount of ozone. In fact, AirTamer® was tested to the California (CARB) standard for air purifier ozone emission, and AirTamer® was given an ozone emission rate of zero. The independent Intertek test report is available upon request from AirTamer®.
    I didn’t request to check upon further with the test report, do you think it is safe to wear this all day and for a long period of time around my necks as I am driving in the city all day. Thanks in advance.

    • If they are making that claim so directly then I am inclined to believe them. Deception with a claim like this would land them in a huge amount of hot water, so I think it’s genuine.

      Given that’s the case, then there is no reason to think this type of a necklace would be unsafe to wear. I think you’re fine to buy and use it.

  33. Hello 🙂
    Thank you for writing this article. If I keep the ionizer setting off (on the coway mighty for example), will the purifier still emit a small level of ozone? It’s hard to find an air purifier with the right CADR without an ionizer option for the area of coverage I’m looking for.
    Thank you!

    • No, it will not.

      For the types of purifiers like Coway Mighty that use an ionizer in addition to other filter types, even when turned on they typically produce only safe levels of ozone. So there’s not much risk there.

  34. I just ordered AD002 Upgraded Air Purifier Necklace with Ultra-high Negative Oxygen Ion Concentration from Is this one safe?

    • Most likely safe, but probably not very effective.

      I really just don’t believe the technology is at a level where these types of necklaces would have a measurable impact. However, because of their size, they also are likely not able to generate high energy ions, which means the level of ozone they create is most likely safe.

      That said, I am just guessing here. I don’t know that product very well. So basing my assumptions on other technology I’m more familiar with.

  35. Hi Derek, thanks for the great and informative article!

    I recently bought a HEPA air purifier that also has a negative ion generator from Amazon (link to product below). To be honest, I didn’t do much research because it had so many good reviews and wasn’t too expensive. After a couple days of use, my girlfriend complained of a stuffy nose, and I’ve been having a consistent minor headache, so I looked up if air purifiers can produce such symptoms and then came across this article (among others) testifying to possible harm from negative ion generators.

    Curiously, it’s hard to find much information on this model outside of its Amazon page (I’m in Germany), but was wondering if you think it’s on the level? Or would I be better sending it back and investing in a purifier without an ion generating function? I should note that I have chronic asthma and so the ozone generation does worry me, but it’s hard to tell how much my machine is actually producing. Any thoughts/suggestions would be appreciated!



    • Typically air purifiers like this don’t create high enough energy ionic particles to be dangerous. However, it’s not impossible.

      I would suggest just turning it off for a while and seeing if your symptoms decline.

    • According to their website, “Complies with federal ozone emissions limit (ARB Certified)”

      So the answer would be no.

  36. Taking the Potential ozone hazard out of the equation, still aren’t these devices simply weighting down particles in the air to the surface which may be the floor but could also be your desktop your bedsheets your clothes etc.? So it may be cleaning the air but really making the surfaces worse!

    • That is basically correct.

      However, it’s easier to clean them from floors and surfaces than it is from the air. So any ionic air purifier would need to be coupled with regular vacuuming and other surface level cleaning.

  37. Hi,
    I am looking to buy Kogan 5 Stages air purifier 3S 12H.
    It mentions about 5 stages purification
    1. Pre filter
    2.H 13 HEPA
    3.Active Carbon
    4.Antibacteria filter
    5.Ionizer helps a neutralize pollutants and viruses using positive and negative ions and hydroxyls.

    Should I buy it Will it harmful?
    What is the different with 3 stages airpurifier (1-3 filters)?
    Do all air purifiers use ionizer system? Thank you.

    • These types of air purifiers are typically safe. While it is an ionizer and most likely creates ozone, it’s most likely not creating high energy particles, and therefore the level of ozone generated is within safe levels.

      The pre-filter is a really basic, usually plastic, filter that traps super large debris…think pet hair, bits of carpet, etc.

      The H13 HEPA is doing the vast majority of the actual work in terms of particulates trapping and removal.

      The carbon filter removes odors.

      Not all air purifiers use ionizers. Some are just HEPA / carbon (in fact those are far amore common).

    • Hi Derek,
      Thanks for your reply.
      It is very useful and I feel confident to buy it.

      There is negative Ion button , should I turn off at all time? Or when I can turn it on.
      Thank you.

    • That’s up to you. I’d leave it on, as I’m confident in the safety for those types of ionizers (they just aren’t all that powerful).

      Turn it off if you’re worried in the slightest. It won’t have a big impact either way.

  38. I have old Sharper Image Ionic Breeze air cleaners that are in excellent condition. Should I not use them and dispose of them?

  39. I have a pacemaker. Will the “electric discharge” interfere with my device? I’m not able to use a scale to weigh myself that measures the water weight because of the electrical current it uses…for example. Just trying to make sure I don’t harm myself while trying to improve my health.

    • Unfortunately, I (nor is anyone at Modern Castle) qualified to answer that question. You should pose that question to your doctor.

      But if you want to be safe, just don’t use an ionizer at all. HEPA purifiers are more than capable of air purification.

  40. Ions that are on a surface can prevent bacteria from growing. Basically, they can not process protein so there is no cell division and they die off. A virus is different but the ion approach still works. Glass, ceramics and Marble/Granite can all be ion exchanged to create silver or copper ions in and on the surface.
    So far, I have ion exchanged silver into/on glass. This produced a slight amber tint and the resulting silver ion surface was tested and certified to be anti-microbial. Awaiting results for anti-viral certification. The company I work for is offering this product for public spaces as sort of a contact barrier. Unlike plexiglass, glass does not scratch and can be cleaned easily. The silver ions are in/on the glass and do not come off as they are part of the glass (sodium comes out and is replace by silver as ion).
    The copper process is better as it is colorless and the ions reduce bacteria colonies faster than the silver ions.
    The company I work for does not do this on marble, granite or ceramics. Just glass and it required high temperatures to exchange ions in glass. On granite or other porous surfaces, heat is still needed but much less.
    I would suggest that if you are interested, research it. Many research documents exist. Works on metals as well but for that, easier to just use real brass or copper knobs on doors and such.
    Ions in and on surfaces are not an issue like ozone or other high energy particles in the air. There are many patents on the silver ion products but they are typically old and no longer enforced. Not all the processes that are patented work but the simple ones do work well, the complicated ones just make it harder to understand the simple method behind the process. The Romans and Greek used this back in the BC and AC times. It is not new and for many years, copper plumbing was the thing. Copper was and is a natural way to kill off bacteria,,, PVC, CPVC, PEX and all the other stuff just don’t do this.
    Do the research, there are safe methods that produce a permanent surface for anti-microbial and ant-viral properties that are safe for your families. Me, just a scientist that researches everything. Then figures out a way to get the same result in a very simple manner. I have quite a few patents for for how to make it better by making it simpler.

  41. I heard that cruise ships are starting to install ionizers on their ships to eliminate covid-19, is this not misleading passengers that this can guarantee to make the ship virus free? Do ionizers produce ozone and do they kill covid-19?

    • I don’t think any person, company, or brand can ever guarantee that any location is “virus free”. It’s just an impossible task, in my view.

      Most ionizers do produce ozone. However, commercial grade ionizers often include an ozone suppression systems. So it may be moot.

      Technologies vary as to how / if they deal with COVID-19. Some can, some can’t. You’d need to see what tests the manufacturer has completed.

  42. Is there anything on the market that still gives the “after a thunderstorm” clean air smell? I loved my old tabletop Ionic Breeze. I have purchased several air purifiers over the year but none of them give off that clean smell. The Ionic Breeze helped me sleep and controlled my rhinitis during the night.

    • There are. Any high powered ionizer will do that. However, it releases significant ozone in the process, which is not safe.

      One of the primary reasons Sharper Image is no longer around is because of lawsuits resulting from the Ionic Breeze, which created unsafe levels of ozone.

  43. I find it very interesting that everyone looks at Ionizers and is only concerned with ozone. Ozone is very harmful however, you can have an ionizer installed and it meet UL 2998 which basically states that no ozone is being produced by this product. No one is looking at the by-product of pumping a lot of ions into a space occupied by people. Those ions create hydroxyls which is part of Reactive Oxygen Species.
    It is well established that oxygen free radicals and their metabolites-collectively called reactive oxygen species (ROS)-can induce direct cell injury, which may trigger a cascade of radical reactions promoting the disease process.
    Lungs are vulnerable to endogenous and exogenous sources of ROS insults. They are well equipped with antioxidant defenses to negate normal oxidative insults. However, when the oxidative defenses are overwhelmed by formidable oxidant influx, injury results. Diseases are linked to this type of influx. Again I am not talking about OZONE. Everyone better get a good understanding on what happens when you introduce tens to hundreds of thousand of ions per cubic centimeter into occupied indoor spaces. ASHRAE 2019 9.4 clearly states that ionizers should not be used in occupied spaces.

    • Thanks for sharing your thoughts, Shaun.

      If the mere presence of a significant volume of ionic particles is really as dangerous as you are asserting then it would seem most regulatory and government bodies around the world have failed in their mandate to protect citizens.

      Why do you think these organizations are not recommendation disuse of all ionizers (even those that do not create ozone)?

  44. Derek,
    Thank you for your response. I will do that. I have also ordered an Ozone monitoring device to see how the levels vary. I believe that there are acceptable levels but for fixed periods of time.
    Thank you again for your quick response.

  45. I recently replaced all of my HVAC units in my house and had Air Scrubbers installed in each unit – 3 total – 2 on main floor – about 3500 sf and one in the basement – 1500 sf. I live in Phoenix so the units run quite a bit. The air scrubbers in installed are by AERUS model A1013P. When we leave the house for a bit and come back you can notice the smell of Ozone in the house. Is it safe to have these units running all the time and is 3 to many to run? Please let me know your thoughts.

    • If you are smelling ozone that’s not good.

      I would strongly suggest you get a professional air quality reading and make certain that the ozone levels are safe within your home.

    • Because of the COVID-19 pandemic and the continuous need for me and my family to go out & meet other people because of work, I’m now considering to purchase portable (necklace) air purifiers that is said to emit large amount of “healthy” negative ions. Do you think these have been tested vs producing ozone? Would you consider it safe to be exposed to such large amounts of negative ions (within your personal space) daily?
      I’ve tried to look for articles explaining the negative effects of being exposed to these kinds of devices for a long period of time and nothing much has come up.
      Hope you could share your views on this.
      I’m thinking of giving these to my family as a Xmas gift.

    • The idea that they are “healthy” ions seems to be a farce.

      I expect what they mean is that they don’t produce a large (if any) quantity of ozone.

      As far as if it’s safe, honestly, it’s an open question. To have these so close to your face and person would be concerning to me, especially at high volumes. While there is no definitive research (to the best of my knowledge) as to the safety or danger of this type of product, I would personally avoid these types of products.

      In my view, an N95 or equivalent facemask is more effective and we know with certainty that it is safe.

  46. hi there, have you come across of a negative ion generator or machine that of great help to paralyzed person or reversed it thanks

  47. Hi! There are a lot of personal purifiers (necklace types) that has come out in the market because of COVID-19. They are mostly ionisers , that emits from 2million to 120million ions per cm3/second and is suppose to create a safe environment within 3 feet of the user. Supposedly safe for the users . There is also this portable LUFT cube that uses nanotechnology. No filter, no ozone, no ions.

    • Yeah, I’ve seen many of them. Thus far I am extremely doubtful of the claims they make and their overall effectiveness.

  48. I live downstairs from smokers living above me. There are evenings I have trouble sleeping the smell of the smoke is so bad. I used to own a sharper image ionizer and it left the room smelling so fresh and clean all the time I loved that about it. But then it broke and shortly after I heard about the emitting of ozone and it not being healthy so I never replaced it. Now years later I have purchased numerous air purifiers including a Molakule, Bluair, and a Conway and so far not one of them has helped with the strong smoke odor. Do you have any suggestions? I really do miss how the ionizer made my room smell so fresh and clean is there anything else out there that is safe that can do that and get rid of the bad cigarette odor?

    • Since you’ve already tried several air purifiers with limited success I think it’s fair to say you need something more robust. You may consider a system like this –

      This is an in-dust ionization system. It creates high energy particles that are great at dealing with odors and other particulates. The creation of those particles mean it also creates ozone. However, it uses a ozone suppression system, so that the ozone does not get into your air.

      Full disclosure, Clean Air Exp is owned by a personal friend of mine. However, I, nor does Modern Castle have any financial relationship with them. As far as ionization systems go, this is the only one I’ve seen that has the right mix of hardware to create effective ions, while still being safe with respect to ozone.

  49. Hello,
    I have one Honeywell HHT-011 air cleaner with Ionizer for each of my 3 bedrooms. These Ionizers are turned on for 8 hours every day, and I have one Therapure TPP300D with UV + Ionizer that is turned on for 8 hours in my living room. Do you think it is OK for the people in my house?
    Thanks for your time.

    • I’m unfamiliar with those models, so I really cannot say for sure.

      I would suggest you reach out to the manufacturer to better understand if / how much ozone they are putting out into the room. As long as it’s none / less than 0.1 ppm then you should be fine.

  50. Hi. As I read… I have 5 Sharper Image Air-purifiers since 2005 that have ionizer… and just learned today Sept. 19th of all the health concerns. Now I understand why they closed all the stores and went bankrupt. They were irresponsible with their units and with the consumers if this was their primary issue in the law suit.
    Moving on, I don’t know if I have a chance in reporting the machines I still own by Sharper Image. Today I am looking for the best option with no ionizer for a space of 900 sq ft and I found Medify MA-40W V2.0 Medical Grade Filtration H13 True HEPA for 840 Sq. Ft. Air Purifier, 99.9%
    And here someone mentioned the Intellipure Ultra AirPurifier… Which if any you suggest. Thanks

  51. I just purchased a Blaux Portable AC F832. It is very small and has a rechargeable lithium battery. It also has a negative ionizer option. Should I be concerned about the amount of ozone it produces or just operate it without the ionizer? Thank you so much for your help.

    • I would just operate without the ionizer enabled.

      It probably is safe even with it on, but no reason to take a chance, in my view.

  52. I recently had a Reme Halo installed in my A/C system. Immediately it gave off a very “chemically’ smell. I have COPD and emphysemia and have been told that any amount of ozone is damaging to lungs. Should I have it removed?

    • I wouldn’t remove it just yet. Turn it off for now if it’s creating a chemical smell.

      I would suggest you hire an air quality specialist in your area to test the air in your home both with and without it running. You need to better understand the impact it’s having on your air and if that’s safe, given your health conditions.

      Ozone typically isn’t described as a “chemical” smell, so I am doubtful that’s what it is, but it could be (or perhaps something else).

  53. We have a Lightning Air Purifier, LA 1500w, that we purchased about 15 years ago. It states Cascading Tower Technology. We only use it on an occasional basis, but started using it again with the wildfire smoke that we are experiencing.
    Should we have any concerns in using this purifier

    • Unfortunately, I am unfamiliar with that model / brand.

      If it’s producing high volume ozone, then no, I wouldn’t risk turning it on. But if you don’t think it’s using ozone to purify the air then it should be safe.

  54. Hi there!

    I was just informed that someone has purchased a Atmosair Matterhorn 1000 Bipolar Ionization unit for our home as a gift. I’m trying to decide if it’s something I should install or send back.

    I’m confused because on the website it says “A safe, natural and environmentally friendly process. Our patented bipolar ionization technology uses no chemicals, heavy metals or mercury, and produces no harmful by-products such as ozone or ultra-violet light.” But all of my research says that ionizers do produce ozone.

    Would you have any insight? Thank you so much!

    • It is possible that it creates no ozone and/or that that ozone is suppressed.

      I recently had a lunch with a friend who has been working in the air purification industry for 30 years. He mentioned to me that there are some new types of ionizers that do not create ozone (a fact that I was previously unaware of).

      It’s possible that their brand of ionization does not create ozone or that it’s so small it’s negligible. I need to do more research on this specific type of technology to say for sure.

      I’m sorry I don’t have a more clear cut answer.

    • Amanda,
      My research also states that any ionizer creates ozone. The EPA made UL 2998 to identify devices that are acceptable levels of ozone. I believe it is 5 parts per billion. I have also read research on the efficiency and toxicological implications of devices that produce ions and they state that in order to remove the amount of VOC’s and viruses in a real life application the PPB would have to be significantly more than 5 ppb. And this would inevitably lead to ozone being released.

  55. I have an air intellipure.. what’s your opinion on this air purifier .. I am also considering air tamer or anion .. or the portable plasma air purifier using plasma technology .. it very confusing what to choose .. appreciate your opinion. Thank you.

    • We haven’t tested the Intellipure yet, so we cannot say for sure. However, based on the specs and other reviews I’ve seen it would seem to be an excellent air purifier.

      Unfortunately, I’m unfamiliar with Air Tamer and Anion.

  56. I recently used a stand alone Hepa and charcoal filter air purifier. It left a nasty smell in the home and increased the humidity in my home. Any thoughts on this?

    Thank you!

    • Was it new? What was the brand?

      I can think of no reason why it would increase the humidity in your home. That to me seems like there must be another factor at play.

  57. Hi Derek, thanks for the info. I did not see the Dyson HP01 or what is called the Dyson Pure Cool LInk Air Purifier above. Locally that is what is available-would you recommend either?

    • Between those, I would go with the Pure Cool Link (which is most likely the Dyson TP01). HP01 offers purifying and a heat function. So unless you really need / want the heat function, no need to pay extra for it.

      We have an extension Dyson Pure Cool comparison here – – if you’re interested

  58. Hi Derek,
    The RabbitAir MinusA2 air purifier advertises that its Germ Defense Filter “traps and reduces airborne bacteria, mold spores, and viruses”.
    You probably get this question a lot-would that include trapping coronavirus? I thought that the virus was too small to be caught by a filter. Elsewhere I have read that UV emitting machines if they are at the right frequency could kill the virus. But I’ve never seen a claim for a filter that way. What do you think? As always, thanks for your information.

    • Hi Bevan,

      Unfortunately, there isn’t a perfect yes or no answer here. And this isn’t just about Rabbit Air, but about all air purifiers.

      An air purifier can help to keep the air in your home or office cleaner, which can help to reduce the chance of coronavirus spreading. But, there are no absolutes. The EPA does a good job of explaining it here –

      As I understand, COVID 19 and other virus / bacteria are able to become airborne by attaching themselves to particulates that float in the air. This can include water droplets (when you sneeze or cough), dust, hair, fibers, mold, pollen, and a slew of other particulates. Air purifiers are able to reduce bacteria and viruses in your home by pulling these floating particulates out of the air and trapping them within their filters. That’s how the Rabbit Air’s germ layer works, and basically how any filter works.

      While the virus themselves may be too small, the virus is hitching a ride into the air on larger particles. It’s those larger particles that are trapped, collectively trapping the virus also.

      As far as UV light, I’m not as knowledgeable about UV light. From what I’ve read and watched it seems to be an impressive technology. However, it be effective they need to be on for an extended period of time and extremely bright. Most of the UV light consumer grade products aren’t bright enough or on long enough to be effective.

  59. Does anyone have any thoughts or advice on CWR’s rechargeable personal Air Purifier. I am a school teacher going back into the classroom would this help at all with Covid 19

    • We haven’t tested it yet, but a quick look at the product’s form factor really makes me question the effectiveness.

      I understand it’s only for personal use, but I am doubtful that it’s capable of pumping out enough air flow to have any significant impact.

    • We haven’t tested it, but based on a quick look at the specs, it is an ionizer, which means it most likely creates ozone. However, given the size, the level of ozone is probably within what the federal government considers safe.

      That said, given the size I am doubtful that it’s capable of having a significant impact on air quality around you. And for $150…yikes. I certainly would not buy it.

  60. Hi, I have an air oasis iadaptair M

    It has uv light hepa and bipolar ioniser. First time using I felt terrible. I assume it’s the ozone from the ioniser. Is it even worth keeper at all or will a standard hepa do just as good? All this information about ozone I’m worried to ever try it with the ioniser setting.

    • Hi Lee,

      If it’s making you feel sick you should get rid of it.

      HEPA filters do just as well as high power ionizers, but without the dangers. Most hospitals still use HEPA filtration, quite simply because it works.

      See our list of air purifier reviews here – – The vast majority are HEPA-based.

    • I would not.

      It appears to be an ionizer. I’m amazed after all of the bad press (and rightly deserved) from the 1990s / 2000s that ionizers like this still exist.

      If this machine creates enough high energy ions to be effective then it’s dangerous due to the level of ozone created. If it doesn’t create enough high energy particles then it won’t be effective. It’s a catch 22 and one that involves your health / safety. To me, it’s not worth it.

  61. Any review you can give me about the Brookstone Pure-Ion advanced ionic air purifier with ozone control? Thank you!

    • I read a few product reviews and I cannot find any models that say “with ozone control”, so perhaps I’m looking at the wrong models.

      In any case, the product descriptions I’ve read leave me worried. It seems like a pretty typical ionizer. If it is (and that’s an if, as I am not 100% sure), then it is dangerous.

      All the places I looked are out of stock / not for sale…that feels to me like it may have been pulled from the market at some point. Given the lack of clear information in the product description I would not ever buy a product like this for my home.

  62. My 2009 Toyota Camry says that it has negative ion air-conditioning. I have never heard of any recalls or problems with it but I do have concerns. Should this be something I need to worry about?

  63. Hi, is the I-wave-R product ok to use? it is installed in the air conditioning system behind the filter. Was offered and installed by my air conditioning company.

    • I’m not familiar with that model, but a quick read through their page makes me a little uneasy. Doesn’t mention anything about ozone suppression or a lack of ozone.

      I would suggest you inquire on whether or not it’s generating and/or suppressing ozone.

    • Hi,

      I inquired with the IWave company. They claim only a very small amount of ozone is released when it first turns on. If on continuously there is basically no ozone… any thoughts?

    • If it’s creating a small amount of ozone then it’s probably safe. You just want to avoid air purifiers that create large volumes of ozone, which can be dangerous.

  64. We need to install air filtration and purification in our house using either room units or something installed into our HVAC system. Considering Molekule stand alone units for each room vs. installing a bi-polar ionization system in our HVAC along with HEPA filtration. The bi-polar unit being considered is similar to the I-Wave R. Since our main concern is killing and eliminating mold particles, would the Molekule be the better choice? A bi-polar system, it seems, would cause any airborne mold particles to fall to the ground but wouldn’t eliminate them unless vacuumed up later whereas the Molekule seems like it would not only kill the particle but also eliminate it completely. Thoughts?

    • That’s generally the way ionizers works (at least to the degree of my understanding). If that’s your primary concern then yes, I would think a standalone air purifier, be it Molekule or something else, would be a better choice for you.

  65. Hi Derek, thanks for all the great information.
    Wondered if you have ever tested the AirTamer302, a personal air purifier from FilterStream using negative ions. The manufacturer says it creates 3 feet of safe space from particles, from pollen to viruses. I read above your concerns that these small devices generate negative ions adequately but are not powerful enough to really be effective. Would you agree with such machines perhaps creating a small area of clean air, but beyond that, not adequate? Thanks much.

    • Hi Bevan,

      Thanks for your comment.

      Unfortunately, I have not tested the AirTamer302.

      But you are exactly right. Many of these air purifiers that include a small ionizer are indeed generating ionic particles, but they don’t have very much energy, so they don’t make it very far into the room…which limits their effectiveness.

      However, that’s also what makes the safe (compared to more powerful ions or ozone generators).

      So in most cases they are probably adding something to the equation as far as total air purification goes, but it’s not a huge amount. Most of your purified air is cleaned via the HEPA and/or carbon filters. They really do most of the work in those types of machines.

  66. I have a Grandaughter with SEVERE ASTHMA what Air Cleaner Should I Get for Her.i Have Research and Still Confused, I’ve Been told to Stick With A Hepic Filter and Carbon Filters. There is 0V200 Oransi Air Purifer Model with Hepic Filter & Carbon Filter or there other more Expensive Model Oransi Max Izonier Air Cleaner with Shut off Button for Izonier. I know I don’t want to Any Ozone. I May of Spelled Company Name Wrong it Might be Aransi or Oransi ? Since your are the expert on Air Purifiers I would Get Any Air Purifier you would Recommend as She is in dire Need For Her Asthmatic Condition. Thank You ! Beverly

    • Their website doesn’t have a ton of info, but it does say it creates ionized particles, which means it is creating ozone.

      It’s lack of clear information about said ozone leads me to believe they don’t use an ozone suppression system.

      In any case, it’s not enough to say if it’s safe or not. However, with this lack of information it’s not something I would be comfortable using in my home.

    • I’m about to have a Reme Halo installed in my yoga studio (which we sometimes use for heated yoga also). In my research it looked like a good option to kill bacteria & virus in the air and on surfaces. Is the level of ozone high with these air purifiers? Is it dangerous to be breathing in the space for 1-1.5 hours at a time? Thank you!

    • It does appear to be an ionizer, but it doesn’t say anything at all about ozone.

      Honestly, I’m not sure about this. The technology is different from many others I’ve seen. Though I’m surprised at the complete lock of ozone mention at all.

      …usually if they don’t create ozone they make a BIG point to say as much. The fact that they don’t is a bit of a flag to me. I would email the company directly and just ask them point blank. Does this create ozone?

    • Thanks for your reply Derek!
      Here’s the response I received from Reme Halo in case it’s helpful for anyone. I need to research ozone levels now.
      Our patented technology produces a vaporized hydrogen peroxide called hydro-peroxides. This is what we use to purify, not ozone. Ozone is a low level bi-product of all electrical appliances. The ozone levels produced by the REME HALO unit is between 0.01 – 0.02 ppm which is well below the EPA’s recommended limit and no more than a copy machine produces. Ozone produced at such low levels is not considered an ozone generator.

      Ozone is a low level bi-product of the UV bulb, it is not what we use to purify. RGF utilizes a custom UV lamp that goes from 100 – 500nm. Any UV bulb that reaches a wavelength of 185nm produces ozone. At 254nm ozone is dissipated. This is a process called ozone degradation. The ozone levels produced by the REME HALO unit is between 0.01 – 0.02 ppm.

    • That’s great! Thanks so much for sharing their response, Rachel.

      If that’s the case, then at least from an ionizer / ozone perspective, it sounds safe to me.

  67. We bought a NuCalgon iWave-R air purifier last year when replacing the HVAC. The iWave-R unit is seating inside the furnace! The unit produces an equal amount of negative & positive ions and claimed that it does not generate ozone! Have you heard of this product? Is it harmful to use?
    Thank you!

    • Unfortunately, I am not familiar with that product and I’m not sure if it’s harmful or safe to use.

      If it indeed doesn’t create ozone then that’s a good indicator to safety, but again, I’m not certain of how safe it is.

  68. I have been using a product called “IWave”. It installs in the HVAC just after the filter.

    I have a foam insulated attic. As with many of these attics there was a moldy smell. We were using a dehumidifier to keep the moisture levels below 50%.
    Our insulation is brittle. Would this be from the dehumidifier?IWave? I was told there is no ozone with the I wave but it uses the process described.

    • I’m not familiar with that exact product, so please take what I say here with a grain of salt.

      1) As far as why the insulation is brittle, I’m not sure. I don’t know much about what makes insulation brittle, other than age. It’s possible your dehumidifier is indeed removing too much moisture and exacerbating the problem, but that’s just a guess. I cannot think of any reason why the iWave or any air purifier would have any impact on the insulation.

      2) If the iWave creates ionic particles then it creates ozone. The ozone levels it creates could be perfectly safe and/or it could use an ozone suppression system (very rare feature).

  69. Hi, I am a Dentist and have restarted my practice post Covid-19 situation. The most significant challenge while operating on a patient are AEROSOLS and Droplets which are in the air for 2 hrs or more. I would like to know how effective is the Sharp FP-J30M-B (HEPA filter Air Purifier) for a operatory of about 100 sq ft. Whats the use of Plasma Cluster Ion Technology in air purification and Ionisation that the company is claiming. Also whether the purifier produces any Ozone and if yes what are the levels. Please suggest any other Air Purifier/Ioniser which will be most relevant to my clinic. Thanks and Regards

    • I’m not familiar with that model, so I cannot say how well it is able to perform.

      100 sq. ft. is a small area, so even the most standard air purifiers shouldn’t have an issue cycling your air several times per hour.

      As far as the “Plasma Cluster Ion Technology”, it sounds like a basic ionizer. I am doubtful the ions are strong enough to have any significant impact on overall performance, especially at this price. If it produces ionic particles then it creates ozone. Ozone in high enough levels is a danger to humans. I cannot say if it’s safe or not.

      I would suggest a non-ionizer for a brand that specializes in air purifiers. See our full list of tested air purifiers here –

      If you can find a Dyson in your region, that’s what I would suggest.

  70. GPS is marketing a Neddlepoint Bi-polar Ionizer for HVAC application claiming high levels of both negative and positive ions but zero emission of ozone. Are high levels of ions safe and effective? The company claims the emission of positive ions neutralizes pathogens but all their data is limited to bench tests. Are there any real life data to support this application in a residential setting?

    • I am unaware of any technology that can create ions without also creating ozone. As long as that ozone is within safe limits then yes, it can be safe. But, if it is within safe limits it also usually means the ionic particles aren’t very effective.

      To my knowledge, I don’t know of any data supporting residential testing of a system like you’ve described above.

  71. Thank you for such an informative and un- biased Article .

    15 yrs ago , I used to have an ionic breeze and was amazed at the difference it made in the air quality of the room . It has long sine died and been disposed of .

    I recently purchased a Sharper Image model 203833-02 to use in an office 12 x 14 to freshen the air that often becomes stuffy . I was planning on running it 24×7. Ventilation in this room is EXTREMELY poor.

    After reading this article I’m questioning my choice ( not sure how I can still purchase a sharper image brand … but was un aware that the iconic breeze was the product that put them out of business) . The new one defiantly does not resemble the ionic breeze I owned before

    I can still return it and get a hepa or something else . I’m a little concerned as there are no operable windows & one door in the space …. any thoughts ?

    • I too am surprised that you found a Sharper Image product to purchase. I’m not sure what model that is, but if it’s an ionizer I would get rid of it.

      Sharper Image’s reputation was forever tarnished, and for good reason. But beyond that, if anything happens down the road you likely won’t have an option for service or warranty as they are long ago out of business.

  72. I´m living in Germany and I have a pretty big air cooler from a random company I don´t know with an “Ionizer” feature. I asked the company how much ozone it emits and they said it doesn´t. :/ Am I in danger? O-o

    • Possibly, but I cannot say for sure either way.

      Bottom line…if a unit creates ionic particles then it creates ozone.

      The only way it’s safe is if the energy behind those particles is small enough that the quantity of ozone created is within acceptable and safe limits and/or the unit uses an ozone suppression system.

  73. Hello, I just ordered one of these on Amazon. It’s for my 19 ft travel trailer.

    Air Purifier HAPHID Pluggable Negative Ion Generator with Highest Output – Up to 32 Million Negative Ions/Sec, Filterless Mobile Ionizer & Portable Purifier for Home /Office Reduces: Allergens,Pollutants, Mold, Germs,Smoke,Etc

    • I’d be interested to hear how well you think it’s performing once you’ve had a chance to use it.

  74. I just purchased Air Genie plug- in ionic air purifiers. I was told I needed one unit per 12×12 space. I purchased these to clear formaldehyde being emitted by new furniture. Will these work for this purpose and are they safe?

    • We haven’t tested them, so I cannot say for sure.

      Given the size of the units, I am doubtful they are that effective. I’ve seen units 10 times this size fail to purify a 12×12 room well.

  75. Hello
    I purchased on air oasis company a HVAC system and I am concern if this product have any side effect on my family
    Thank you

    • I’m unfamiliar with that company.

      If you’re concerned you may want to contact a local air specialist, someone who can test the air in your home to verify safety.

  76. Do you know the model number of the Sharper Image Air Purifier that was involved in the lawsuit or does it apply to all of their air purifiers?

    • I don’t know the exact model number.

      But it was their line of Sharper Image Ionic Breeze air purifiers.

  77. Hi, thank you for all the information. Just want to ask about the personal wearable air ionic perifiers. I cannot find anything on the product website that addresses ozone. Do you have any thoughts on the wearable devices? Thanks much

    • It’s likely that the ions generated via this necklace aren’t powerful enough to harm you.

      However, I also think it’s doubtful that a device this size would be effective at purifying the air.

      High energy ions = great at cleaning air at distance, but dangerous
      Low energy safe ions = not great at cleaning air, except at close range, but safe

      Because the range is so close there’s a possibility it actually does purify the air well, but I do have my doubts given the size and the fact it’s powered by a battery.

  78. Hello, I purchased 2 of these to be used in the highschool basketball gym that is about 5000 sq ft. It will be used when we have practices and games. I would like to know if it is safe to use. After reading this article, I am not sure anymore.
    New Comfort Commercial Air Purifier. (link to product)

    • You absolutely should NOT use it while anyone is in the gym. It is not safe to use when humans or animals are present.

      I would suggest you reach out to the manufacturer to see how long they suggest running the ozone generators for a space that size and how long it will take for the ozone to dissipate. You need to give it adequate time to dissipate from the room before people are safe to go back in that space.

  79. 嗨!德里克:

    • 謝謝!




      Thank you!

      Yes, that is my understanding also.

      Most ionizers operate well below this level. The only ones I would be really careful of are those that purifier that air as an ozone generator. Those have the potential to be far more dangerous.

  80. Hi, do you think this “Woodpecker High-pressure Plasma Air Purifier” is safe and effective for use in a dental surgery?
    we are considering due to COVID-19, it’s really difficult to understand whether HEPA/UV/ or this “High Pressure Plasma Air Purifier” would be the best option
    There are 2 sizes and we would be looking at the Q3 as it is a small room <25 square metres. Thanks in advance.

    • I’ve never heard of that brand and the amount of information provided here just isn’t sufficient to say whether it’s safe or not.

      I’m also not as familiar with Chinese product safety standards. Which makes me more uneasy to say one way or another.

  81. Hello,
    I just bought the Aera Max DX5 air purifier but it has a PlasmaTRUE Technology- Creates an ionized field to help safely remove airborne pollutants.
    I was wondering what does that mean and if its harmful to us.

    • Most air purifiers with an ionizer feature on the market are perfectly safe. I just took a quick look at the Max DX5 spec’s and I don’t see anything that would lead me to believe it’s not safe (that said, the spec pages I was able to find don’t even mention an ionizer).

      Air purifiers with an ionizer are generally safe because the ionizes are not energized enough to be harmful to you.

      What you want to avoid and/or be extremely careful use are standalone ozone generators, like this – – while it can be safe if used properly, it is harmful to humans. So you need to only use it in locations where people won’t be in the area while it’s in use and after for some hours.

  82. This is a wonderful article. I am dentist in UK and do you have any suggestions as to which purifier to use in a dentist room from removing the viral load standpoint? Any specific model you would recommend which are not ionisers as from your replies I gather Ioniser with Ozone is not good in the long run. many thanks

  83. First I think this article was written with much effort. I give credit for effort and intentions. Ions are the most infinite broad subject matter on the earth. The number of different areas multiple degree physicist’s run the show behind closed doors under disclosure statements world wide is rarely a thought in someones lifetime. Most who understand nature and ions on a basic multiple subject range have a natural or 6th sense aptitude beyond books. Albert Einstein is an icon example of that and MIT level knowledge on up. A privileged society of savants.Derek did a very good job writing on such a subject. Cars cats and dogs account for most people in the USA. Yet few can answer 1 factual ionic basic basic minor question about them. Yes you need proper static balance in homes for physical and mental heath as do your pets. Open windows and get outside touching earth…dirt and grass ect. Adults 1hr a day, children 4 to 6hrs and thats minimum hrs every day. or best possible. A city boy knows not to fight a country boy, maybe 3 4 city boys or more, an old ion bred statement. Ionizer air cleaners work wonders and enjoy every extra day you can best you can. USA homes are a quagmire of chemical / mycotoxic pollution brought to you by ionic proton unbalance factors suspending dust and your lungs are like a dryer lint filter of sorts. Besides the ionic electron unbalance taking away your abilities on every scale and why people are fat or no common sense anymore and pills. 4 bucks Durk Pearson MIT genius used paper back Life Extension 1983 10mns a day is the best advice besides dust free home solutions and free from me no schooling ever taught you or search engine. The above is a brief ETSE theory based on a nano scale. Einstein’s greatest. Einstein’s Theory of Simplicity of Explanation. The greatest teaching theory of modern times. I am just a fan and we all owe our life to him for what we have. Wishing everyone well.

    • Thanks for sharing your thoughts, James. Appreciate your feedback and additions to the conversion!

  84. I have a portable air quality monitor that I carry on my backpack and every time I get into my car I get warnings about the dangerously low air quality. I want to buy an air purifier for the car and was particularly interested in the Hompo Car Air Purifier:

    Can you tell from the specs if it’s safe? Alternately, can you recommend a safe and effective air purifier?


    • Nothing in the specs is a red flag to me. It should be perfectly safe.

      What you want to avoid are air purifiers / cleaners that are marketed as an “ozone generator” those are dangerous for people to be around.

      The the vast majority of ionizers on the market, especially in countries with good safety / product standards, are perfectly safe to use.

  85. Hello Derek,

    Was also looking to purchase the REME Halo LED. It is made by RGF Environmental Group Inc. Their website states they manufactures over 500 environmental products and has a 35+ year history of providing the world with the safest air, water and food without the use of chemicals.

    REME stands for Reflective Electro Magnetic Energy. They state it uses UV technology and the Ceramic Catalysts and produces hydrogen peroxide.

    It is a bi polar ionizer but they claim it is “Zero Ozone Compliant” (<0.02 ppm)

    Would this be okay to use all day in the house everyday in terms of this ozone level? Is this safe enough to use? Is this similar to the Ozone levels being outside? It will be installed in the duct work of the AC unit and we have the AC unit on everyday.

    Also if the charge off makes particles stick together and larger for the air filter to capture that is good, but it is bad if we breath in the larger particles before they are captured by an air filter?

    Thank you so very much for your response!

    • If the ozone counts are that low then yes, it will probably be safe to use.

      According to the NASA / EPA, “In the troposphere near the Earth’s surface, the natural concentration of ozone is about 10 parts per billion (0.000001 percent). According to the Environmental Protection Agency, exposure to ozone levels of greater than 70 parts per billion for 8 hours or longer is unhealthy.”

      I haven’t tested this model, but from the specs page it does look really impressive. This seems to be a scaled down commercial style purifier, so that’s a good sign.

      When an ionized particle comes into contact with a floating particulate it changes the charge / weight and falls to the ground. So you won’t breath those in.

  86. Are you familiar with idf filter? I recently bought Honeywell Air genius 5 and it has an idf filter which is permanent and washable. Is idf safe and does not emit harmful ozone?

    • Hi Jon,

      I’m not familiar with IDF filters (very little info online that I can find).

      However, I don’t believe they would be harmful. Also, the filter itself would not emit ozone.

      Ozone is generated by purifiers that create ionized particles. The more energy behind those particles, the more ozone created.

  87. Hi, I am searching for air purifier safe for people with lung disorders. I thought about Reme Halo, a whole house air purification unit that also works on germs & virus etc. They advertise about hydro-peroxide indoor air quality. Wished you could offer any information or opinion; and or add to your research.

    • Any HEPA air purifier is going to be the safest option. I would suggest you avoid any type of ionizer.

      Whole home systems can be great, but of course they are more expensive. In either case, I would stick with a HEPA purifier system (whether it’s a standalone unit or whole home).

  88. Hi,
    I have the Airthereal APH260 Air Purifier, what do you think of that one? It has an ionizer you can turn on and off, and a UV sanitizer you can also turn on and off. Is it safe to use the UV all the time? Is it a good strategy to run it all day, but use the ionizer and/or UV sanitizer maybe once during the day for a short time, or on and off to ensure there’s no excessive ozone production? Also, there is a good H13 HEPA air purifier, the Medify MA-25, high CADR, but H13 HEPA filter only, no bells and whistles, just a straight up high filtration rate unit. Between that, and the Airthereal APH260 with ionizer/UV but lower CADR, which would be better for general air cleaning, and also for cleaning the air of mold? Thanks!

    • Just took a look at it on Amazon.

      They don’t even mention the ionizer in their product description, which makes me think that it’s probably not very effective.

      UV sanitizers are good and based on valid tech, however, it’s only going to sanitize the surfaces that it touches. You cannot UV sanitize air particles. For UV to work it has to be bright enough / constant enough on a surface that it can take effect. As for UV safety, it should be fine as it’s not coming into contact with your person.

      Since I don’t see any info on the ionizer I don’t want to say one way or another if it’s safe to use all the time. As far as UV goes, yes, that’s fine to leave it on all the time. There are not safety concerns with the UV light because it’s internal on the machine.

      I haven’t tested this Airthereal model, so I don’t want to compare it to a traditional high function HEPA purifiers. That said, in my experience, the vast majority of air purification power comes from the air flow of the unit and HEPA filter. I won’t go as far as to say that UV light and ionizers have no impact, but their impact is far less, in my opinion.

      High volume HEPA air purifiers are still used by hospitals for one simple reason…they work.

  89. Thank you for this thread. I used to own 4- XJ 2000 ionizers and used them for years. The brand I used was microtec and i see different companies make them but the unit is the same. After using them for some time, they stopped working and I either threw them out or stored them away. I did see the benefits with my family as I have two sons who were borderline asthma. They are teenagers now and have outgrown their asthma. I found one of my old ionizers and took it apart and cleaned it inside and out and I got it to work again. I started using it again in our bedroom and started to read comments here and other websites. I have been looking for a couple more but it looks like no one stocks these models anymore. I see the concern how some folks have issues with ozone and now I am thinking maybe I shouldn’t use it anymore. I figured its small enough, but it does give a clean smell which I can notice. I have a 2000 sf home and I only have it in our bedroom and I don’t think I am exposing too much ozone. Any additional advice or knowledge you can share on the subject? Thanks again.

    • Best advice I can give…if you think there is any reasonable chance that the machine is creating any significant volume of ozone you should stop using it.

      The benefits vs. risks just don’t make sense.

  90. Hi,
    what do you think about NCCO technology? I searched a lot but I’m not able to say if it releases ozone or other pollutants

    • If it’s similar to other catalyst oxidation systems I’ve tested I would say it’s good, not great. The other systems I’ve tested in the past weren’t able to achieve particle counts as low as standard HEPA air purifiers, while also costing more.

      They aren’t bad by any stretch, just not quite as good as others.

  91. Hi,

    Thank you for your article which helps me understand more before buying air purifier. Just some questions, is air purifier with negative ion of 20 million/cm3 safe to use?

    Can you look also into UV Care brand?

    • It’s not the quantity of the ions, but the energy behind them. More energy = more ozone = greater danger (unless there is an ozone suppression system, which is rare and expensive).

      Thanks for your suggestion on the UV Care brand. We’ll add that to our research / test list.

  92. I have an older Bell and Howell ionizer. I love the fresh smell in my bedroom but I guess that is from ozone so I should get rid of it to be safe?

    • I don’t know much about that specific model, Dawn, so I cannot say for sure.

      But the machine does look very similar to the Sharper Image Ionic Breeze that put Sharper Image out of business (due to the lawsuits).

  93. Can you suggest a good brand to use? I would like to have something that is safe, effective but also easy on the budget. Thanks.

    • Unfortunately, there is no standalone ionizer I would recommend that is safe, effective, and budget friendly.

      If it’s safe / budget friendly, it’s ineffective. If it’s effective / budget friendly, then it’s not safe.

      The problem is that in order for an ionizer to be highly effective it needs to create high energy particles. If it’s creating high energy particles then it’s also creating ozone. And breathing ozone is dangerous to humans in these types of quantities. A machine that creates high energy ions needs to also have an ozone suppression system, a feature you don’t see often outside of commercial units.

      Regarding the ionizers you see as part of air purifiers, those are safe, but they don’t create high energy ions. So they really cannot get very far out into the room (more energy = more distance = more ozone created). I wouldn’t go as far as to say they are without value, but most of the purification on those machines is still being handled via the HEPA air purifier. The percentage of purification coming from the ionizer is minimal, in my view.

  94. Hey! Have you tested the Blaupunkt ADH501? It’s a dehumidifier with built in Ionizator. I’m wondering could it be leaking ozone, it has both an active carbon filter and the ionisation. I’ve used it for a few months and since my house was very humid before, it seems to have helped on that account, but I’m still doubtiong the ionization function on it.

    • Unfortunately, I have not yet tested that model.

      When you create high energy ion particles that is what creates ozone. So if the ionizer is broken then it’s not creating any ozone.

  95. Hi, I am researching the “air genie”
    Model: PNP-130
    Anion Power: <1W
    Anion Output:
    From Breathe Greene Co.

    I am having a horrible time getting any testing information. Marketing and Opinion Reviews don’t count; I am looking for facts, testing, meeting USA regulatory compliance etc.
    Any information is greatly appreciated!

    • Hi Debi,

      Unfortunately, I’m not familiar with the Air Genie and we have not yet tested it.

      I took a look at their product page and see they are marketing it as an “ozone purifier”. That to me is a red flag. Ozone purifiers are not safe to use unless you are not in the room while it’s purifying. Even then, it needs time to disperse the ozone after generation.

      I would suggest you consider other products.

  96. Hi, I just learned about one called the Ritello by Librex. They did a demo and looked very impressive, and since they claim the water does the filtering, you don’t have to replace expensive filters, so they give you 21 year warranty. I have found little to no reviews on it, and I’m wondering if you have experience with it or know about it. Has ionizer and UV as well as a small back-up HEPA filter and is medical grade. Would love your input. Thanks.

    • Unfortunately, I’m not familiar with that model. So I cannot really for sure.

      Sorry that I cannot be more help.

  97. I recently bought an ionized air purifier with a HEPA filter and it’s begun producing a sweet smell, almost like baked goods. I’ve done some “googling” and have come up with mixed results about the ozone it could be producing. Some sites saying it’s leaking and I should get rid of it and evacuate and other sites saying it’s a manufacturer problem. Is it still safe to use? How can I get rid of the sweet smell it’s producing? Thank you.

    • What model is it?

      It could be leaking ozone, but I don’t think the sweet smell is ozone. Most people describe the smell of ozone as closer to chlorine.

      As far its safety, you should contact the manufacturer immediately. Ozone or not, that’s an abnormality.

  98. What about plasmawave ? According to my research this doesn’t produce any ozone ! BTW is plasma ionizer the same bipolar ionizer ?

    • This is the first I had heard of the Plasmawave. I just talked with a friend of Modern Castle, an air purification expert that has been designing and building air purifier systems for 25 years.

      Here’s what he said:

      “If an air purifier doesn’t create ozone then it’s not effective against pathogens. They create weak and short lived ions. These type units might create ions that might do a little something within 3-6ft and may filter air within a small area. The UV does nothing to air flow. The UV can have an affect on stationary surfaces only.”

  99. I found your information doing research for my severe contact dermatitis. I have done patch testing and have stopped using all skin care and cleaning products that contained the allergens that I reacted negatively too. However, this did not prevent sever flares particularly in my face. As a result I am now on immunosuppressant medication. We have several New Comfort ionization machines in our home. When we first got them my husband turn them on high which resulted in severe coughing and asthma conditions for me. We turn them down on low and my Dr prescribed an inhaler for me until my breathing was normal again. My question to you is could this also be causing an allergic reaction with my skin?

    • Hi Diane,

      Unfortunately, that is well beyond our expertise level to say. You should consult your doctor with that question. They will have better knowledge than we do.

      If you think a product (any product) is making you sick you should stop using it immediately.

  100. In reply to your (Derek Hales) response to Cari; what about a hepa air purifier that has a ionizer switch? In that case you can leave the purifier running 24/7, would it be helpful to turn the ionizer on only every few days?

    • I would also suggest leaving the ionizer on for the same reason.

      Ultimately, both the ionizer and HEPA filter are working collectively to remove particulates floating in your air.

      If those features are not on then their performance will reduce, and particulates will increase in your air.

  101. What is AQI. Why don’t you write down what the letters mean e.g. US Food & Drug Administration (FDA) and then you can use AQI. However, if you explained this in the beginning and several paragraphs have been written, then explain the letters again. Derek Hales used it in his explanation and I suppose no one thought to find out what he was talking. I would assume Air Quality Index, however what do I know, you wrote the article and maybe you don’t know what Derek Hales was talking about. By the way who the hell is Derek Hales?

    • My apologies.

      AQI = Air Quality Index

      It’s a measure used by governments to communicate how polluted the air is. The higher the number, the worse your air quality is.

      I am Derek Hales. I run Modern Castle, along with a small team. You can read more about my team and I here –

  102. Idea: just don’t leave the air ionizer air purifier constantly on. Use it every couple of days. Some air purifiers come with the air ioniser option, it’s just turned it on and off over time. Don’t have it on consistently. If you think your air is polluted in your house, just use it for an hour or a few hours or every couple days and then once a month or something like that or once a week. Just an idea.

    • I’m not sure that would work well for most homes, Cari.

      The problem is that most homes let particulates in from the outside almost constantly. Opening doors, windows, and HVACs are the most common ways that particulates get in your home. I live Phoenix, Arizona, a city with relatively low pollution. However, our outside AQI is frequently between 50 and 80. This isn’t bad, but it’s also far from good.

      With air purifiers running all the time in my home I’m able to keep a PM2.5 of less than 2 just about everywhere.

      However, all it takes is turning the air purifiers off for a couple of hours to see that rise to 10-20 AQI. And it will keep increasing from there.

      In some areas of my home I can see an increase from AQI of 1 to 15 in as little as an hour.

      As a result, I think it’s far better to leave your purifier on most of the time, but definitely all the time you’re in your home.

    • Hi, just to clarify your answer to someone else’s question earlier. I have the option to switch the ionizer on/off, but you recommend we leave the ionizer on when the air purifier is in use, otherwise the purifier is a lot less effective? The model is ‘BONECO P340’. Also can you tell me how to test the PM2.5? Many thanks, keep well 🙂

    • I wouldn’t go as far to say that ionizers on air purifiers are not effective. However, they respective portion of air purification is small compared to what the fan / HEPA filter accomplish on their own.

      For an ionizer to be really effective it needs to generate high energy particles. If it’s generating high energy particles that means it’s also generating lots of ozone. If it generates lots of ozone it’s not safe, which is why you don’t see those types of machines sold much any more. If they are sold, they are done with lots of warnings to make sure you’re not in the room while it’s in use.

      So to answer your question…you can leave the ionizer off without dramatically negatively impacting overall performance.

      As for checking PM2.5, you’d need a test meter. Something like this – – this is what we use to test.