In this article, we’re going to answer two of the most common questions people have about air purifiers, “what does a air purifier do?” and “how do air purifiers work?

So if you’ve been wondering these same types of things, then this post has everything you need.

Below, you’ll learn what is an air purifier and how it works to remove pollutants from your indoor air. You’ll also discover what an air purifier can’t do for you so you don’t have any false hopes.

As home air quality professionals, we want you to walk away with expert knowledge on this topic so you can decide if an air purifier is right for your needs. And when you’re done here, be sure to check out our top 10 air purifiers list for the best-rated choices. as well as our best air purifier with washable filter page that shows you the top models that are the cheapest to use over the long term.

What Does an Air Purifier Do?

An air purifier works to clean the air. Air purifiers do this with filters and advanced air cleaning technologies. These units remove pollutants like allergens, bacteria, dust, toxins, and odors so the air is healthier to breathe.

Now, every air purifier works differently so if you’re wondering what does a air purifier do, then you need to understand this concept a bit more.

The exact particles that are removed with an air purifier will depend on the type of filtering technology you choose. Some air cleaners use a fan and a set of filters to trap particles as air flows through the unit, while other air purifiers neutralize particulates in the air without filtering them at all.

Additionally, some air purifiers include technologies that can destroy microbes and pathogens at their core so they become harmless to your health.

By adding an air purifier to your home, you can ensure that pollutants that cause breathing issues and health problems are eliminated from the airspace around you.

What you’ll notice after using an air cleaner inside your house is that you’ll have an improved immune system, deeper sleep, and an overall better feeling of health. 

If you suffer from asthma or allergies, you should also notice significantly lesser respiratory and nasal issues, making your quality of life much better.

And these days, there are now automatic air purifier units that detect the air quality inside a room and automatically adjust themselves to remove pollutants at the fastest rate. Many of these air purifiers are also Wi-Fi enabled and can be controlled by your smartphone.

See all of Amazon's Best Selling Air Purifiers

How Do Air Purifiers Work?

Air purifiers work in four primary ways: collecting solid particles in an air filter (HEPA), neutralizing contaminants in the air with an electrical charge (ionizer), trapping odor molecules in a filter (activated carbon), and breaking pollutants apart (UV light).

That’s the basic idea of how does an air purifier work. We’ll now look at each of these four types of air filtration methods more in depth.

HEPA Filter

If an air purifier is built with a HEPA filter, then it operates by pulling air into a dense, woven filter and trapping the particles inside so they can’t float back into the air.

HEPA filters are so efficient that they can capture up to 99.97% of particles down to 0.3 microns in size. That’s why this type of filter is used in the best air purifier for asthma because HEPA filtration traps microscopic particles that trigger asthma symptoms.

Activated Carbon Filter

An Activated carbon filter works by trapping molecules that produce odors inside the home. This filter also removes gaseous pollutants and chemicals known as volatile organic compounds (VOCs).

Activated carbon filters are the only type of air filter that can adsorb chemical vapors. A HEPA filter cannot do this because it only captures solid particles.


An air ionizer is a type of air purifier that uses an electrical charge to neutralize pollutants. And it can work in one of two ways:

  • By sending out negatively charged ions into the air that latch onto particulates. This bond causes the pollutants to stick to surrounding surfaces and fall onto the floor.
  • By drawing air through the unit and collecting particles on a set of charged metal plates or rods. This acts similarly to an air filter but pollutants stick to the surface of the material and the plates must be washed clean.

Because a room ionizer air purifier doesn’t use degradable filters, it’s the most affordable type of air cleaning device you can buy.

UV Light

As we explain in our article on what does a UV light do on an air purifier, this air cleaning technology uses a non-lethal form of radiation that’s emitted through a light inside the unit that attacks bacteria and viruses as they pass through the system.

A UV light works by breaking apart the molecular structure of microbes and pathogens to render them harmless to your health. None of the other air purifier technologies mentioned on this page can work this way.

This sums up the various methods of how do air purifiers work.

As we mentioned above, some products include one or more of these features to strip harmful particles from the air.

Depending on how you want the product to operate will determine which options you should look for in a device.

Who Should Get an Air Purifier?

There are some signs that might indicate that you may need an air purifier to help address them. Allergy symptoms in the forms of a stuffy nose, itchy eyes, and headaches can be a sign that too much pollen or mold spores are in your living area.

If you have asthma and you are seeing more flare-ups than normal, your home might not have great circulation and may need some help. If you walk around your living space and just see dust everywhere – on picture frames, on wooden tables, etc. – it might be from the air instead of not cleaning enough. Lastly, if your space is starting to smell because bad odors are lingering, it might be time to get an air purifier to help circulate the air. 

What Do Air Purifiers Remove?


Allergens are substances that can create adverse immune responses in the form of allergies or asthma. Air purifiers can remove airborne allergens like pollen and dust mite waste.

Bacteria and Viruses

Bacteria are microbes and viruses are submicroscopic infectious agents that can cause a number of infections, diseases, and illnesses. Air purifiers can work to destroy these microorganisms and pathogens floating indoors.


Dust is made up of a number of things, such as skin cells, hair, clothing fibers, bacteria, dust mite waste, bits of dead bugs, soil particles, pollen, and microscopic specks of plastic. Air purifiers with a high CADR rating (or Clean Air Delivery Rate) can do a good job to remove these particles from the air so a room stays cleaner.

The CADR rating indicates how efficient the air purifier is at removing three substances: dust, pollen, and smoke.

Mold Spores

Similar to allergens, indoor mold particles can be harmful to people with allergies, asthma, and respiratory conditions. Air purifiers can extract mold spores form the air so they don’t enter into the human body as well as slow down the growth of indoor mold.


Odors are caused by one or more volatilized chemical compounds. Odors come from all sorts of things, like cooking, smoke, mold, garbage, and human beings. Air purifiers with the right type of filter can trap odor molecules so the air smells fresh.

Pet Dander

Pet dander is a particular type of allergen that’s composed of tiny flecks of skin shed by cats, dogs, rodents, birds and other animals with fur or feathers. Air purifiers can reduce the level of pet dander to help alleviate allergy symptoms and to keep a room cleaner.


Smoke is a combination of many substances, including tiny solids, liquids, and gas particles and it can contain hundreds of different chemicals and fumes that are visible and invisible to the eye. Air purifiers can work to eliminate smoke particles and its associated odor.

Volatile Organic Compounds

Volatile organic compounds or VOCs are organic chemicals that have a high vapor pressure at room temperature. Common examples of VOCs that are present in our daily lives include benzene, ethylene glycol, formaldehyde, methylene chloride, tetrachloroethylene, toluene, xylene, and 1,3-butadiene. Air purifiers can capture VOCs from the air so they don’t end up harming human health.

What Air Purifiers Won’t Work For

Now that you know the basics behind how do air purifiers work, it’s also important to understand that these units won’t remove or neutralize all aggravating particles in your home.

Some contaminants sit on interior surfaces like furniture, bedding, carpeting, and walls. When this happens, the air purifier cannot lift the pollutants off of these surfaces to remove them from the room. Air purifiers work best to remove contaminants that are floating in the air.

Therefore, an air purifier won’t work well for these situations:

  • Dust that has already accumulated on soft or hard surfaces.
  • Odors that are continuously emitted by a single source.
  • Allergens that brought indoors on a daily from open doors and windows.
  • Mold that is actively growing on a surface.
  • Bacteria and viruses that are constantly being spread by a sick person.

To get the most benefit out of an air purifier, it’s best to do a thorough cleaning of your home before using the system as well as taking other steps to create cleaner air in your home. By removing the source of contaminants, you can help the air purifier work better at cleaning the indoor air.

Disadvantages of an Air Purifier

While air purifiers are easy to start and let it work, it can be a chore to remember to change out the filter. And if it is not switched out, the filter itself could become a hotspot for mold and bacteria growth. While air purifiers do help clear the air, there is not one that cleans the air 100%. Some air purifiers may work better on bacteria than smoke and vice versa. It all depends on your needs and wants.

Surprisingly, air purifiers may also add ozone emissions into the air as a byproduct. Also, if the pollen, dust mites, and other particles are not in the air but on the ground, rugs, or even furniture, the chances of them being caught by a purifier are very slim.

When Should You Use an Air Purifier?

You should use an air purifier when you want to remove certain particles from the air. Air purifiers are best used to get rid of dust, allergens, mold spores, bacteria, viruses, pet dander, and smoke. Using an air purifier can give you cleaner air to breathe and reduce your exposure to harmful substances.

The best way to use an air purifier is to run it 24 hours per day, 7 days per week. The more time an air purifier has to filter the air, the cleaner that air becomes.

Every air purifier has a particular ACH rating (or Air Changes per Hour) that indicates how many times the air is clean every 60 minutes. A 4 ACH means that the air is filtered four times per hour (or every 15 minutes). The higher the ACH rating, the more efficient the unit is.

Benefits of Air Purifiers

We cover the best air purifier advantages in another article, but to sum it up, an air purifier offers these benefits for you:

  • Removes allergens
  • Controls asthma triggers
  • Eliminates airborne chemicals
  • Traps smoke
  • Neutralizes odors
  • Traps bacteria and viruses
  • Improves sleep
  • Helps with pet dander and hair
  • Removes PM2.5 particulate matter
  • Can increase life expectancy

Additionally, while medications and treatments for conditions like allergies, asthma, and respiratory conditions can help alleviate symptoms and prevent reactions, an air purifier does help to remove the sources that cause your symptoms to occur.

Research studies report that after continued use of an air purifier, patients can experience fewer allergic reactions and asthma symptoms. However, air purifiers are not meant to be a direct replacement for medications; however, air purifiers can be beneficial to prevent the aggravating particles from getting into your eyes, throats, and lungs in the first place. Always talk to your doctor before reducing or stopping any medications.

Bottom Line

The best air purifier for you will depend on your particular needs. So when you’re trying to pick the top air cleaner for your home, consider the technologies that impact what do air purifiers do as discussed on this page.

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About David Morrison

David is an Air Quality & Comfort Technician. He has expert knowledge on the technology and design of air purification, air conditioning, and heating systems. His main role is to write content that helps people get the most value out of their air purifiers, air conditioners, and heating units. (See Full Bio)


Frequently Asked Questions

Where should you place an air purifier in your home?

It is best to keep it away from other items that might result in it falling over or not being able to circulate the room’s air. 

How long does it take for an air purifier to clear the air?

Depending on the air purifier you purchase, it could clean the air in a room within 45 minutes to three hours. Of course this also depends on the size of your room, how many particles are in the air, and if you change out a filter (if you have one). However, you can feel a change in the air even sooner than that.

What types of particles can an air purifier remove?

There are plenty of particles air purifiers can take out of the air. Some of the most popular ones include allergens like pollen, dander from your pets, and those ever-seemingly invisible dust mites. Air purifiers also have the ability to take some amount of mold out of the air. Other particles include some smoke (if your air purifier contains a filter) and even some toxins like those from cleaning products.