Air ionizers have been around a long time but have started gaining popularity in recent years. There is a lot of confusion about air ionizers (also called negative ion generators), namely which pollutants they actually remove. Their name is often connected to bacteria, viruses, and other very small harmful particles in the air. One of the major questions in connection with this is, do air ionizers actually kill viruses?
The short answer is: no, air ionizers do not actually kill viruses, but they do remove them from the air. They achieve this through the use of negative ions, which “fuse” together with these airborne viruses, pulling them to the ground. Once a virus is on the ground, it is up to us to remove it from there by wiping it away or vacuuming it. In this sense, we do not actually kill the virus with air ionizers, but just prevent them from being able to reach our lungs. Ozone generators and UV-C light air purifiers are the only two air purifier types (currently) that can actually kill (destroy) viruses.
Since viruses are not considered living things, you technically can not kill them. A more appropriate word here would be “destroy”. You can kill bacteria, and destroy viruses. However, for the sake of simplicity, we are just going to stick with “kill” for viruses in this post.
That being said, I am going to give a more detailed answer in the paragraphs below. I will not address the subject of how an air ionizer works, since I have already covered that extensively in my other blog posts – you can read about that here.
Effectiveness of air ionizers against different types of air pollutants
The first important thing to clear upfront is to answer which air pollutants can an air ionizer remove. There is quite a bit of misinformation out there regarding air ionizers which I want to clear up. In general, we have 10 types of air pollutants – these are:
- Formaldehyde, Gasses & TVOC
- Mildew & Mold
- Bacteria & Viruses
- Pet dander
- Paint fumes
- Dust mites
- PM 2.5
All of these air pollutants have different sizes, which is measured in micrometers. In order for you to get an idea of the size difference of these pollutants, refer to the graph below. This information will get very handy later on, which is why I included it in this post.
Common Indoor Pollutant
Particles Size in Microns
Pollen, mold and plant spores
VOC (volatile organic compounds)
Less than 0.001
Air ionizers remove all of the above air pollutants from the air. That is right, each and every particle listed. This is why we consider air ionizers to be the most effective air cleaners on the market. This superior cleaning ability, however, comes under one big condition – the amount of negative ions that the air ionizer releases has to be big enough.
While negative ion generators (another word for air ionizers) effectively remove all air pollutants, they need to produce enough negative ions – we are talking about millions of negative ions per cm3, per second. This is because every harmful air particle takes at least 1 negative ion (sometimes even more). So each harmful particle in the air needs its own negative ion to pull it down to the ground, effectively neutralizing it. If there are not enough negative ions in the air… that means that some harmful air particles will remain untouched. This is the reason why some people report that air ionizers are ineffective – simply the issue of an ionizer emitting too few negative ions.
For smaller rooms, I recommend at least 6-8 million negative ions per cm3 per second. This will ensure that you get the full benefit of negative ions and their superior air cleaning ability. Anything less than that and you will risk some air pollutants going unchecked, leaving the air quality worse than it would otherwise be.
Types of air purifiers that can kill viruses
Air ionizers are just one subcategory of air purifiers. There are many other types of air purifiers, some effective against viruses and some not. We can categorize air purifiers into four main subcategories:
- air ionizers (also called negative ion generators),
- HEPA filters,
- Carbon Activated filters – standalone or part of a HEPA filtration system,
- UV-C light air purifiers,
- and ozone generators (also called ozonators).
Each one of these uses a completely different air cleaning technology. Not every air cleaning technology is effective for all types of air pollutants. In the table below, I have specifically pointed out which type of air purifier can kill viruses and bacteria.
Air purifier type
Can it kill viruses?
Carbon Activated Filter
Not in a traditional sense- only removes them from the air
As you can see, only air ionizers, ozonators, and some UV-C light air purifiers are effective at dealing with viruses – air ionizers remove them from the air, while ozone generators and UV light can actually kill them. Air ionizers achieve this with the help of negative ions, ozonators with ozone, and UV-C light with specific wavelengths. Each one of these air purifiers has a different factor that decides how effective the device is at killing/removing viruses. For air ionizers this is the emission of negative ions, for ozone generators it is the amount of ozone production & exposure duration, and for UV-C light air purifier, this is the wavelength, measured by something called nanometers (nm).
HEPA filters and carbon activated filters are sadly not very effective at removing viruses. This is due to the very small size of viruses, which can simply just pass through the filter, without getting captured. The same goes for carbon activated filters, which specialize in odor removal and are not effective against viruses.
Which air purifier should you choose for killing viruses
From what I have written so far, you really have only 3 options for killing or removing viruses. Out of all the air purifier types, only an air ionizer, ozone generator, and UV-C light are the viable options here. Each one of them has their own use, and comes with its own set of disadvantages.
Negative ion generators (air ionizers) would be my default option for “killing” viruses. Out of the three possible air purifier types, air ionizers come with the smallest downsides and have the biggest benefits at the same time. As I already wrote, the only concern regarding air ionizers is the emission of negative ions. If it is high enough, then you are good to go. The only downside you have here is the fact that most air ionizers produce ozone, which is is a lung irritant. This is why you always have to check how much ozone an air ionizer produces. While 0.05 ppm is the max allowed concentration, you should always aim towards zero. Some air ionizers produce no ozone, which is ideal. If you want to learn more about why air ionizers (and other types of air purifiers) produce ozone, feel free to check my other post where I tackle this question.
Quite a big number of air ionizers on the market do not have a high enough negative ion emission. And if they do, people use them in spaces and rooms that are larger than the actual air cleaning capacity. This is why you always need to check for the negative ion emission and room coverage.
I would choose ozone generators for killing viruses only for rooms which are not often occupied. So this would be an ideal pick if you had a virus or bacteria problems in a warehouse, garage, basement, or some other similarly often unoccupied/emptyroom. This is because of all the health risks associated with a large amount of ozone, which is what ozone generators use to purify the air. While ozone generators focus mainly on smells/odors and mold, they can effectively remove all living organisms too (including viruses), but on two conditions – a big enough ozone output, and duration of the purifying process. Industrial ozone generators work best for removing viruses just due to the huge output of ozone. Sadly, a huge ozone output is devastating to the human body, animals, and even plants. You should never stay in the room while an ozone generator is working, and up to 4 hours after it has finished working. So can you can see, this can be pretty limiting and makes ozone generators not really that great of an option for a living room or a bedroom.
UV-C light air purifiers
UV light is fantastic at killing viruses, bacteria, and every other microorganism. It can also be a great disinfection tool. Unfortunately, this is pretty much the only thing it can do good. UV light air purifiers are unable to remove other types of air pollutants, which ozone generators and ionizers can. Most UV light purifiers also produce ozone, which is another big downside. Cheap units can also be problematic, as the technology does not sometimes allow for effective germ removal. UV-C air purifiers work by using a fan to suck the air into the device. The air then passes by these UV lightbulbs, which destroy all pathogen microorganisms. Many cheaper units do have high enough exposure time to effectively deal with all of the viruses and bacteria. I would recommend this option if you actually want to destroy specifically only viruses and not just remove them from the air.
What about HEPA filters with a UV light or an ionization function?
I already said that HEPA filters are not effective against viruses. But, there are some air purifiers on the market that use a multi-layered filtration system, which uses HEPA filters as the “main cleaning unit”, and has other filters or air purification methods added. Sometimes these combined devices also come with a UV-C light or a negative ion generator. In most cases, these combined air purifiers are not good enough to kill or remove viruses. This is simply because the “secondary” filtration system (added UV-C light or air ionizer) is simply not strong enough. Does it still work? Sure it does, just not as great as a standalone UV light air purifier or air ionizer. I would make an exception here only for the expensive, top tier combined air purifiers. These usually do have strong enough components to effectively deal with viruses too.
Do Air Ionizers Kill Viruses – Conclusion
If I summarize the whole post, we can say that air ionizers do not kill viruses in a traditional sense, but rather remove them from the air. Even tho the air ionizer does not directly kill (destroy) the virus, it does remove it from the air which is good enough, as negative ions also prevent the virus from going back into the air again (where we then inhale them). Air ionizers, however, are not the only air purifier type that can do that – UV light air purifiers and ozone generators actually have the ability to kill (destroy) viruses. If you have a virus problem or want a preventive measure for viruses/bacteria… then an air ionizer or UV-C light would be my first recommendation. Just make sure that the air ionizer’s negative ion emission is high enough, or that the UV-C light air purifier is not the cheapest one possible. Ozone generators are the best virus-killing solution in warehouses, garages, or other, often unoccupied rooms.
If budget is not an issue then it would also be possible to look at a top tier HEPA filter that has an added negative ion generator or UV-C light. But in most situations, you would want to pick the other two air purifier types (standalone units) I mentioned in the paragraph above. No matter which air purifier type you choose in the end, always weigh out their other benefits and drawbacks, and you should be good to go.