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What does an air purifier do?

Updated on November 22, 2023
Written by
James Booth
James has over ten years experience as a content producer and editor. He focuses on writing articles that are compelling, clear and, more importantly, helpful to the readers. He honed his research and copywriting skills working as part of NeoMam Studios, the parent company of HouseFresh.

Air purifiers can remove ultrafine particulate matter from your environment by sucking in the air, passing it through a series of ever-finer filters and then expelling clean air back out.

With the risks of indoor air pollution, removing these from your environment using an air purifier has many health benefits. This is especially true for asthma and allergy sufferers, those with long-term conditions, young children and older people.

That said, scientific research shows that air purifiers can greatly benefit anyone who is struggling with the following:

  • Seasonal allergies
  • Asthma caused by dust mites or pet dander
  • Mold
  • Traffic pollution
  • Wildfire smoke
  • Chemicals and VOCs
  • Unwanted odors

If you decide an air purifier is right for you, choose one fitted with activated charcoal and HEPA filters. This combination can effectively remove ultrafine particulate matter, gasses and smells from your environment.

If you’ve been wondering what the buzz is with air purifiers, you’ve come to the right place! With more and more people worried about indoor air quality, air purifiers have become increasingly popular.

This is particularly true in the last few years:

Researchers have even found that adults exposed to poor air quality and pollutants in their early life are more likely to develop severe respiratory issues such as Chronic Obstructive Pulmonary Disease, asthma, allergies and decreased lung function.

But what — you may be wondering — can an air purifier do about it? Let’s start from the beginning.

How do air purifiers work?

Much like the name suggests, air purifiers work to clean your air. They do this by drawing in the air in your environment using fans, passing them through a series of filters and then expelling the cleaned air back out again.

That, in a nutshell, is the entire process. But, of course, it’s a little more complex in reality – so we’re going to break down each stage more comprehensively!

Stage 1: Pre-filtration

The pre-filter has the largest filter and removes larger particles from the air. This could include dust, hair and pet dander.

The pre-filter could be made of various materials such as plastic mesh, material, or a metal grill. Depending on your air purifier, you may be able to either remove the pre-filter and clean it by hand, replace it (eventually), or clean it within the unit.

Pre-filtration removes these larger particles first, allowing HEPA filtration to be more effective in the long term.

Stage 2: Activated carbon filtration

The next stage in filtration is for your air to pass through an activated carbon filter. Not all devices will be fitted with one, but we highly recommend units with activated carbon because these filters can remove odors and VOCs (Volatile Organic Compounds) such as formaldehyde, benzene and chloroform.

Odors that your activated carbon filter can remove include:

🍳 Cooking smells and smoke
🚬 Tobacco or weed smoke
💩 Bathroom odors
🐕 Pet odors

Activated carbon filters have been treated with hot air, steam, or carbon dioxide to create a network of minuscule pores inside the carbon that can trap gaseous pollutants (including VOCs and smells) as the air flows through the filter:

VOCs are found in household items, such as cleaning products, aerosol sprays, paint, and more. They have a range of negative health effects, so it’s essential to minimize your contact with them — especially in the air you breathe.


Check out our detailed post on how activated carbon filters work for a detailed breakdown.

However, while carbon filters are excellent at removing these, they cannot remove some smaller ultrafine particles, such as mold, pollen and bacteria. This is where the next stage in filtration comes in…

Stage 3: HEPA filtration

Finally, the last stage in air filtration is High-Performance Particle Air (HEPA) filters – the finest level of filter that your air passes through and, arguably, the most important.

While the other filters will have already removed larger particles by the time the air reaches the HEPA filter, they can remove even smaller pollutants, including:

🦠 Bacteria and viruses
🍄 Mold spores
🌺 Pollen
🌫️ Smoke particles

HEPA filters are made up of fiberglass strands woven together tightly to form a labyrinth that particles must pass through to be expelled back into your environment. Because the fiberglass strands are “sticky”, any ultrafine particles can become trapped against them — even particles as tiny as 0.3 microns.

This study from 2020 published in Environmental International proved that HEPA purifiers could remove ultrafine particulate matter from the environment efficiently and could do so at a similar rate to the standards set by the Association of Home Appliance Manufacturers.

The different types of HEPA filters are:


Check out our detailed post on how air purifiers work for more detail about every stage.

5 health benefits of air purifiers

Now that you know what air purifiers do to the air, let’s discuss the health benefits of cleaning the air you breathe. 

1. Air purifiers keep allergy triggers under control

If you suffer from seasonal allergies (a.k.a. seasonal allergic rhinitis), you’ll know how they can affect your daily life (cue a runny or stuffy nose, incessant sneezing, itchy or watery eyes, etc.)

According to this 2018 study in the Asian Pacific Journal of Allergy and Immunology, HEPA air filters significantly reduced particulate and high-density matter allergen concentrations. This greatly improved the effects of allergic rhinitis in the 32 clinical subjects who took part.

This was also backed up by this 2020 study in the Yonsei Medical Journal, where researchers found that air filters could reduce high-density, matter-induced allergic rhinitis.

Air purifiers are so good at removing allergy triggers from the home that this 2014 study in the Journal of Asthma recommended that all households with allergy sufferers should install a high-performing air filter home ventilation system!

2. Air purifiers reduce the amount of dust and dust mites

Dust, or more specifically, dust mites and their faeces, are a huge issue for people with asthma, but an air purifier can help.

In fact, according to The American Academy of Pediatrics, allergens and pollutants are a huge contributor to premature death in children caused by asthma.

One of their recommended intervention methods was using HEPA-fitted air purifiers in the home, which could positively affect the asthma-related morbidity rate.

As shown in this study in the European Respiratory Journal, the recommendation for people living with asthma was to combine air purifiers, and hypo-allergenic mattress covers to trap dust and dust mites in order to reduce the amount of histamine produced in the body.

📄 If you are still unsure, this 2020 article from the Yonsei Medical Journal showed that air purifiers could benefit children with asthma by significantly reducing particulate matter levels in the home. 

3. Air purifiers remove mold spores from the air

Mold in the home can be unsightly and have severe health repercussions, as this study in the Annals of Allergy, Asthma, and Immunology showed. The EPA lists various mold-related health problems, including allergic reactions and asthma.

However, this study from 2018 published in Biocontrol Science concluded that HEPA-fitted air purifiers could significantly remove fungi and mold from home.

The CDC notes that severe reactions to mold can include shortness of breath or fever.

4. Air purifiers effectively remove pet dander

Pet dander (the dead skin that comes off your pets) can be a huge issue for allergy sufferers. The EPA notes that pet dander is one of a range of biological pollutants in your home that may affect indoor air quality.

Luckily, air purifiers are very effective at removing pet dander from your home — thereby reducing allergy or asthma-related problems caused by pets. This 1999 study published in Allergy found that HEPA air filters could reduce airborne dog allergens in your environment. 

According to the Journal of Allergy and Clinical Immunology, air purifiers could positively affect breathing in young people living with asthma who had pets in the home.

5. Air purifiers can rid the air from odors, pollution and smoke

According to the American Heart Association, pollution and smoke can lead to heart attacks or strokes (amongst other issues). Specifically, wildfire smoke can affect children and cause respiratory issues or exacerbate existing allergies, asthma and other chronic health issues.

But this study from 2021 published in Heliyon showed that HEPA air purifiers were very efficient at removing indoor air pollutants, especially small-sized particles. In addition to this, the Environmental Monitoring and Assessment showed that air purifiers could effectively lower ultrafine particulate matter in smokers’ homes and significantly reduce carcinogenic exposure risks.

Researchers who wrote this 2021 study in the Journal of Hazardous Materials specifically found that air purifiers were the most cost-efficient technology at removing ultra-fine particulate matter caused by pollution.


Check out our science-backed benefits of air purifiers for more on this topic.

Final thoughts

As you can see, there are so many benefits to investing in an air purifier.

They are useful devices essential in any home or workplace if you’re concerned about indoor air quality. Additionally, ensuring clean air is one of the key takeaways for healthy living, according to the EPA.

Convinced? If you’re looking for recommendations for air purifiers, be sure to check out some of our air purifier reviews and our lists of best air purifiers available on the market to help you decide.


About the author

James Booth

James has over ten years experience as a content producer and editor. He focuses on writing articles that are compelling, clear and, more importantly, helpful to the readers. He honed his research and copywriting skills working as part of NeoMam Studios, the parent company of HouseFresh.