Informational Guide

What Does An Air Purifier Do & How Does It Work?

by Josh M

With indoor air quality being a major concern, especially as of late, air purifiers are becoming more and more popular. What does an air purifier do, and do they actually work?

We will take a close look at air purifiers, explain the science behind their mechanisms and figure out how they work and what they do.

On the surface, an air purifier is a machine that removes impurities from and sanitizes the air in our homes. This is important because, according to the EPA, indoor air quality can be up to five times higher than outdoor air.

Unlike an air filter that just captures the pollutants and removes them from circulation, an air purifier is designed to get rid of the pollutants permanently. How do they work, and are they worthwhile? Let’s find out.

Where to Place an Air Purifier

How Air Purifiers Operate

Air purifiers come in many shapes and sizes but have the same operation and setup. There is an internal fan system that will pull air into the unit from the room. Then, the air is passed through various types of filtration and sterilization methods before being pushed back out into circulation.

While some pollutants can stick to hard surfaces like ceilings, walls, and even furniture, the airborne contaminants will eventually cycle through the system. When running, air purifiers will replace the air volume of your home anywhere from 4 to 24 hours.

Of course, proper placement and enough room for airflow and proper circulation of the home are required. But, when set up correctly, the air in your home can be purified in a single day and continuously as long as the purifier is running.

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Air Purifier Filtering Properties

Air purifier filters come in a wide range of types, styles, and sizes. These are all designed to capture and remove different types of pollutants. Everything from dust and dander to mold, bacteria, and even viruses can be removed from circulation and your home using the right filtration.

While we cover the different filter types in more detail below, it is essential now to talk about the impurities and sizes. Small particles are measured in microns. A micron is also called a micrometer, and it is a measurement that equals one-millionth of a meter.

To put it in perspective, the best human eyes, unassisted, can see items that are 40 microns in size or larger. A human hair is 70 microns in diameter. Indoor allergens range between 2 and 5 microns wide, bacteria are 3 microns, and viruses are 2 microns or less.

Air purifiers use high-density fibers, paper, mesh, and other materials to create a deep woven mesh that prevents items down to 1 micron from passing through. A paper HEPA filter you may use for your central AC unit, for example, will stop particles down to 3 microns, at best.

Effectiveness and Purifier Needs

Are air purifiers effective, though? It generally depends on your expectations and filtration needs. Taking the recent pandemic into account, for example, the novel coronavirus (COVID-19) is typically about 0.1microns in size.

However, it cannot travel on its own and must attach to a larger particle like a droplet of water, mucus, or aerosol. When this happens, the virus (and other particles) become airborne and can be removed by a purifier.

This factor makes them effective at bacteria, allergen, and virus removal. Not every house needs an air purifier, though. These machines are much more expensive than an air filtration system and require more expensive replacement parts.

They are most effective for small homes or used in a single room. Larger, multi-story houses will require more machines to be effective. For the cost of 3 or 4 purifiers, a central purification system connected to your HVAC setup may be more viable.

Types Of Filtration Explained – How Do Air Purifiers Work?

As we mentioned previously, there are several different filter types. Some capture, others remove, and still others neutralize. Most air purifiers will use one or two filtration methods, often combining a capture and neutralizing filtration method. Let’s take a look at the different possible filtration methods to learn more about them.

How Air Purifiers Clean Air


A pre-filter is more for the actual purifier than it is for your home or air quality. These filters only capture and collect dust and debris to keep it from getting into the fan motor area and causing issues.

While they do work to help minimize contaminants in the air, they are more designed for the longevity and effectiveness of the other filters. They aren’t dense, usually a sponge material, and won’t capture small particles below about 30 microns.

Activated Carbon Filter

Activated carbon or charcoal filters are made to capture foul odors. The carbon is a natural odor absorbent and will collect smoke, fumes, chemical odors, and gases from pollutants known as volatile organic compounds, or VOCs.

Activated charcoal is the only material that can absorb gases and odors, making it highly viable in purifiers to help improve the smells in the room. Because other filter types do not remove fumes and odors, using an air purifier that includes carbon will greatly improve your enjoyment of the machine.

HEPA Filter

HEPA filters have greatly improved over time and are now the de facto filtration method for allergens, sensitivities, and air quality. These filters use a dense weave of filter material to capture the smallest particles.

Modern HEPA filters can stop particles down to 0.3 microns in size. This means that they can capture many airborne particles but may not capture all bacteria or viruses in the air. With a 99.97% effectiveness rating for most filters, HEPA can be used in almost any filtered appliance, including air purifiers.


Ionizers are not a filter type as much as they are a stand-alone capturing device. There are two main types of air ionizers. Both use negative ions to attract the positive ions in allergens, molds, and bacteria.

One type of ionizer will send out negative-charged ions into the home. As they travel around your home’s air, they attach to particles and create an unbreakable bond. This added weight to the particle causes them to fall to the ground, where they can be wiped off of shelving or vacuumed up as needed.

The second type is an internal model that uses charged plates or rods. The negative charge attracts the pollutants that then stick to the plates and are effectively removed from the air. The plates or rods must then be manually removed and cleaned to remove the particles and continue operation.

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UV Light

Like activated carbon, UV Light is a specialist system that does things no other filtration type can do. UV light doesn’t capture particles or retain dust and debris. Instead, UV light is used as a cleanser and purification method.

UV light works to destroy bacteria and some viruses. It doesn’t remove the molecules but instead breaks them down, making them no longer harmful to humans. After that, the particles can pass back into the air, harmless, or they can be captured by other filtration methods.

Like the activated carbon, UV light is not very useful on its own, but used in conjunction with other filtration methods inside an air purifier will have much higher benefits.

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PlasmaWave is a patented technology from Winix. The method here, like carbon and UV, is that it attacks the particle and virus molecules instead of capturing them. Like the negative ions from carbon, PlasmaWave attaches to the particles and uses what Winix called Hydroxyls to neutralize the bacteria.

It works by removing the hydrogen from the molecular structure of the virus or bacteria. This, over a short time period, eliminates the effectiveness of the molecules leaving your air cleaner and fresher.

Currently, this method of filtration is only available in Winix products. However, if it proves viable, it may be adapted to other brands and products in the near future.

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Filtration At A Glance

In the chart below, we look at all the filtration types to compare them on their filtration abilities.

Filter Type Anti-allergen Anti-Odor Antibacterial Antiviral
Pre-filter No No No No
HEPA Yes No Yes Sometimes
Activated Carbon Yes Yes No No
Ionizer Yes No Yes Yes
UV light No No Yes Yes
PlasmaWave Yes No Yes Yes

Reasons To Get An Air Purifier

There are plenty of reasons to add an air purifier to your home. But they may not be needed by everyone. One of the best indicators of the need for an air purifier is the overall health of your family.

If you or other family members have itchy, watery eyes, stuffy noses, or constant headaches, it may be due to poor indoor air quality. In these cases, an air purifier will help keep the allergen triggers to a minimum.

You may also notice an abnormal amount of dust collecting on flat surfaces. This can occur even with regular cleaning and doesn’t mean you are dirty. However, it can indicate your home has poor or blocked air circulation. Air purifiers will improve air circulation and make the air being circulated even cleaner.

Finally, if you notice a stale or musty odor (or any general bad odor in the home) that is not accounted for by regular cleaning, it could be in the air. Air purifiers with activated carbon will help remove the stale, musty odors.

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Air Purifier in the Living Room

How To Make Your Air Purifier More Effective?

Air purifiers can be quite effective when used properly. However, there are a few measures you can take to improve their overall performance and value.

For starters, you want to ensure the proper placement of the machine. This will include not blocking the vents (input or output) and ensuring there is enough space around the unit for air to circulate. Sticking the unit in the corner is not a good idea as it can prevent proper air circulation for your home.

You also want to point the output airflow into the center of the room and not into a wall or direct the louvers to the floor or ceiling. Another factor is runtime. It may seem counterproductive to run your air purifier constantly, but the longer it runs, the more air it can clean. Leave your unit on at all times to maximize performance.

Lastly, you will want to perform regular and routine cleaning and maintenance. Replacing or cleaning filters, wiping the machine down, and cleaning out the vent ports, as well as replacing UV lights as needed, will ensure the unit works at optimal levels.

When Should You Avoid Air Purifiers In The Home

Air purifiers aren’t the answer for many preexisting conditions or situations. Depending on your current air quality level and the root cause for the issues, an air purifier may not be the best answer.

For example, a home that already has accumulated dust build-up won’t see a reduction in dust levels. You must first thoroughly clean the house to remove the dust manually. Sourced odor problems will also not benefit from an air purifier.

If you have standing mold, clogged drains, or other odor-producing sources, an air purifier won’t make them go away, and the odors will remain. Having open doors and windows will prevent the machine from properly circulating the contaminated air and replacing it with cleaner air.

Finally, if bacteria and viruses are being spread by an actively sick member of the household, the air purifier can minimize the contamination but won’t remove it. The best case is to clean, deodorize and repair your home prior to using the air purifier. Once the source contamination is removed, the air purifier will work to keep it that way.

People Also Ask (FAQ)

Where should you place an air purifier in your home?

Air purifiers need to be placed in a central area with proper circulation. It is best to have a few feet of clearance on all sides. However, air purifiers can be placed in living rooms, bedrooms, or even hallways to help move air and improve indoor air quality.

Can you sleep next to the air purifier?

There are no major issues when using an air purifier while and where you sleep. However, if you are sensitive to dry air, you may want to position the unit to blow away from you instead of on you. Otherwise, like a fan, an air purifier will move air around the bedroom while you sleep.

Do air purifiers make the air dry?

No. Air purifiers, as their name implies, clean and purify the air. They do not have any mechanisms inside like portable air conditioners that remove moisture from the air. However, circulating air can cause skin dryness and can cause your skin to become more dry, as well as eyes and nose issues, if dry air is a sensitivity. In these cases, you don’t want the air purifier to blow directly on you, but this is the only concern.

What are some of the top brands of air purifiers?

There are many manufacturers and brands of air purifiers. The most notable are Honeywell, Coway, Blueair, PureZone, and Austin Air. While there are air purifiers made by most HVAC brands, these are some of the top names and most reliable brands currently on the market.

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Air Purifiers


Air purifiers are a method of improving the indoor air quality of your home. While there is some debate among consumers if air purifiers actually work, the answer is that they can. A lot will depend on current conditions and how much cleaning you do to the home before adding the purifier.

With the right model, proper clearance, and regular maintenance, your new air purifier can last you a long time. During that time, it will perform well to reduce contaminants and allergens in your home and keep your air fresh and clean.

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Last Updated on January 9, 2023

Josh M

My name is Josh and I am obsessed with the HVAC industry. I created this website to help HVAC techs of all levels get the best out of their heating & cooling systems. I have spent thousands of hours studying air conditioners, heaters and home air products so you can learn & buy with confidence. Learn more about the team here.