Do Air Purifiers Really Work? Research Suggests They Have Benefits

With the number of people with asthma and other respiratory diseases constantly increasing in the US and elsewhere, the world is desperate for solutions.

One of the solutions put forward to help prevent allergies and asthmatic reactions is air purifiers. But that begs the question, do air purifiers work?

As with all promising, relatively new technology, there is a lot of skepticism. This article will explain what air purifiers are, how they operate, and if they do indeed work.

What are Air Purifiers?

There is something wrong with the air we breathe. You know that I know that, everybody knows that. We know there are pollutants in the air, and quite frankly, there is very little we can do about those.

In general, developing countries with a lot of manufacturing activities tend to have more pollution than others. We have all seen pictures or videos of cities covered in smug.

However, even developed countries like the US struggle with pollutants and allergens that cause or worsen the prevalence of respiratory illnesses such as asthma.

But in either case, that is not the type of air pollution we can fight with an air purifier.

What we can fight against are particulates in our homes, such as mold spores, pollen, pet dander, dust mites, and tobacco smoke.

These are the home pollutants that air purifiers filter, as they are the most common causes of respiratory allergic reactions. 

How do Air Purifiers Work?

Air purifiers cleanse the air we breathe using different methods, depending on the size of the room, how toxic the air is, and your location.

The three main ways they purify air are:

1. Filtering particulates

The most common type of air purification involves the use of high-efficiency particulate air (HEPA) or other filters to trap particulates. They can remove 0.3-micrometer particles and should remove at least 99.7% down.

Given that particulates are the major causes of allergic and asthmatic reactions indoors, this method of air purification can be very effective. However, as the filters hold the particulates, instead of eradicating them, they need to be replaced often.

The one danger of this is that many cheap filters use paper or other organic materials that can encourage the growth of spores, which can worsen allergic reactions.

So ensure that you only use synthetic materials, ionizing purifiers, or change the filters often.

2. Kill germs

This is what most people expect from an air purifier. The idea of a machine that instantly destroys all pollutants on contact is very appealing. These machines use thermodynamic sterilization and ultraviolet irradiation to kill microorganisms.

However, these can only be used in controlled environments such as labs and sterile rooms in hospitals, etc.

They are also quite expensive, as you can imagine, and maybe overkill, considering filtration systems are effective against most particulates.

3. Remove volatile organic compounds (VOCs)

Many of the chemical products we use in our homes, such as paints, varnishes, disinfectants, degreasers, and cleaners, have organic solvents.

Unfortunately, these products often release VOCs, which is why they are more prevalent indoors than outdoors.

VOCs have been reported to have adverse short and long-term effects on health. They may affect people with pre-existing respiratory conditions or cause them in healthy individuals.

Some air purifiers are capable of removing VOCs to varying degrees. Given their high level of toxicity, this may be a deciding factor when choosing an air purifier.

What Types of Air Purifiers are There?

There are quite a few air purifiers, each with its unique way of purifying the air, what they are helpful against, and where they can be used. Common types of air purifiers include:

1. HEPA filter air purifiers

As mentioned previously, these are the most common type of filter purifiers. Different types of products and designs can be called HEPA filters, with a range of applications from air purifiers to vacuum cleaners.

To be classified as such, the filter must only allow at most 0.03% of particles to go through, and none can be larger than 0.3 micrometers.

There is also the ultra-low penetration air (ULPA) filter, which goes beyond the capabilities of standard HEPA filters. Despite the name, ULPA and HEPA must allow a certain amount of air to pass through, based on strict guidelines.

2. Activated carbon air purifiers

Unlike HEPA and ULPA, carbon air filters are designed to capture gasses in the air instead of particles.

Activated carbon can remove volatile organic compounds (VOCs) like formaldehyde, benzene, methylene chloride, and other pollutants like nitrogen oxides from the air by chemically binding them on tiny binding sites.

The gases (air) pass through activated charcoal (the carbon) and stick to it. This is similar to how charcoal has been used for centuries to get rid of bad smells.

For the charcoal to be more effective, it is ‘activated,’ meaning the surface area is significantly increased so that it can absorb more pollutants.

This type of cleaner is also known as adsorbents, not to be confused with absorbent. Instead of the gas being absorbed into the charcoal, it simply clings to the surface.

While these are highly effective against VOCs and gases, they are relatively ineffective against particles. Larger particles get trapped in the lattices of the carbon, but smaller ones are released back into the atmosphere.

So, if you are concerned about allergies and respiratory conditions caused by or exacerbated by dander, pollen, mold, or dust mites, activated carbon air purifiers won’t do the trick.

3. Ionizing air purifiers

Unlike the previously discussed purifiers that filter out or prevent the flow of particles or pollutants, ionizing purifiers work best by allowing the particles to flow freely!

An ionizing purifier created charged molecules (ions) using corona discharge. This discharge causes the molecules to become either positively or negatively charged.

This positive or negative charge causes them to attract particles with the opposite charge.

As the dust and other particles stick to each other, they become heavier and eventually fall to the floor. They may also be drawn to carpets, curtains, chairs, or other stable objects in your home.

Ionic purifiers, as they are also called, can be fanless or have a fan. The advantage of the fan is that it caused the air to circulate quicker. However, the fanless variants are quieter.

In order to make them more effective, ionizer air purifiers can come with a HEPA filter to remove particulates or activated carbon to combat VOCs.

As with all air purifiers, there is a downside, and this one is pretty huge. Ionizers can produce ozone, which is a lung irritant. The United States Environmental Protection Agency (EPA) strongly advises against using any product that generates ozone.

While ozone in the stratosphere is good, ozone in the atmosphere (the air we breathe) is terrible. On top of that, there is no research that suggests that ionizers that produce a harmless level of ozone are effective for air purification.

4. Ozone generators

based on our review of ionizers, you can already tell this is not going to be an option, but let’s dive in anyway.

Ozone generators work similarly to ionizer air purifiers by releasing a corona discharge or UV light to alter the molecular state of oxygen.

The oxygen we breathe is dioxygen, meaning it has two molecules. When this oxygen gets an extra molecule, it becomes ozone.

Imagine a toad with three eyes, and you have an idea of why ozone is a bad idea.

While it is true that ozone can purify the air, it does more harm than good. Ozone is unstable, and the gas is harmful to people.

It also reacts with other chemicals and can create even more toxic molecules.

Ozone generators are also powerless against VOCs. On the contrary, ozone may even cause more VOC emissions from chemical compounds around the house, making it even more dangerous.

When a large quantity of ozone is released, it can be effective against pollutants. But, of course, this level is dangerous to people.

Which is why it is only used on an industrial scale, where people are absent, and the area is adequately ventilated afterward.

5. Ultraviolet radiation

While short-wave UV light (UV-C light) can be used in ozone generators, it can also function independently. For example, ultraviolet radiation sterilizes microorganisms such as bacteria and viruses.

The devices are also known as UV germicidal irradiation (UVGI), and they have been used in different medical capacities over the years.

For this to work, the air that passes through the device must spend enough time for the microbes to be thoroughly incapacitated.

While the idea of an air purifier killing germs is intriguing, the reality is not so. While UV-C light is effective against microorganisms, it cannot filter particles, so it is limited in its ability to protect people with respiratory conditions.

That is why UV-C light purifiers are often used with other options such as HEPA air filtration systems. But, on top of that, UV lights can cause ozone, which we have established as very harmful.

So, even though large units can be effective against bacteria and viruses, the creation of ozone negates any perceived advantages. And so, for the time being, this type of air purifier should remain on the untouchables list.

6. Industrial air purifier

this isn’t technically a type of air purifier, as it could be any of the ones listed above, but significantly larger and more potent at cleaning the air.

These units have also overcome some of the barriers or restrictions of their residential substitutes, but they are either too large or too expensive to be used in homes.

Some of these units are capable of filtering the air in an entire building ten times per minute.

Are Air Purifiers Effective?

To answer the question ‘do air purifiers work?’ it is important to add: against what? Against dander, allergens, and particulates, air purifiers have proven to be effective.

The EPA recommends portable air purifiers as a way of improving indoor air quality, but with a strong caveat. 

Air purifiers cannot wholly eradicate pollutants from your home. On top of that, they tend to target either particles and gases.

While HEPA and ULPA can eradicate most of the particles, some will escape, while others are already on floors and surfaces.

As a result, two things are recommended. The first one is prioritizing cleaning as the most important way of getting rid of allergens, dust, and toxins.

The second is to use an air cleaner that targets both particles and gases, such as a HEPA with activated carbon. This will protect not just people with respiratory infections against allergens but also protect healthy inhabitants from VOCs.

Another way to make the most of air purifiers is to ensure that the clean air delivery rate (CADR) is the adequate size for the room. An air cleaner with a higher CADR and a fan will purify more air and quicker, making it more effective.

It is also critical to ventilate your home correctly, even when you have a powerful air purifier. The primary concern about air purifiers is the creation of ozone.

As we have emphasized, it is best to stay away from ozone generators, UV lights, and ionizing air purifiers. Their disadvantages grossly overcome their benefits. Worst of all, they can actually worsen the health of the people they are trying to protect.

When you do use the right air purifiers, you must also change the filters as often as necessary and keep them clean. Otherwise, even they can become health hazards brought about by poor indoor air quality.


In brief, air purifiers have been shown to clean the air from dander, mold spores, dust mites, toxins, volatile organic compounds, and smoke.

While every air purifier can sterilize at least one type of pollutant, many variations are either not very effective or can release toxins into the air.

The best type of portable air purifiers can filter both particles and gases and not release any ozone.

It is also important to change the filters often and not rely on air purifiers as the sole source or even the primary source of improving your home’s indoor air quality.

The best way to protect people with allergic or respiratory concerns is to clean your home often, keep it ventilated, and use an air purifier with a high CADR.

Once you have all these things in place, you can expect to answer the question ‘do air purifiers work?” with an emphatic “Yes!”

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Melanie Mavery is an aspiring HVAC technician who is fascinated by the trends and opportunities in the HVAC industry. She spends most of her day writing content on home improvement topics and outreaching to prospects.  She's always looking for ways to support HVACs!