What Does an Air Purifier Do? | How Does It Work?

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What Does an Air Purifier Do | Know Your Facts

Have you ever wondered what that slightly stale odor in your home is? Or why do your allergies seem to flare up more indoors than outdoors? The air inside our homes can accumulate a variety of pollutants like dust, pet dander, smoke residue, volatile organic compounds (VOCs), and more.

Long-term exposure to poor indoor air quality can lead to respiratory issues, headaches, and other health problems. This is where air purifiers come in – but what does an air purifier do exactly?

An air purifier is an electrical appliance designed to remove airborne contaminants from the air in a room or indoor space. By filtering out allergens, smoke particles, odors, and other pollutants, it helps improve indoor air quality and creates a fresher, cleaner breathing environment.

In this guide, we’ll explore how air purifiers work, what they can remove from your home’s air, and the key benefits of using one.

How Air Purifiers Work – The Purification Process

At their core, most air purifiers work using a simple three-step process:

  1. Air Intake – A fan or blower system draws in air from the room into the purifier unit.
  2. Filtration – The contaminated air passes through a series of filters that capture and remove pollutants.
  3. Air Output – The now cleaned air is blown back out into the living space.

This continuous cycle of air cycling through the purifier allows it to constantly filter out unwanted particles and purify the air. But how exactly does the filtration itself work?

What Does an Air Purifier Do?
Air purification system in general – Image credit

The most common air filtration technologies used in purifiers include:

HEPA Filters

  • HEPA (High-Efficiency Particulate Air) filters are made of tightly woven fiberglass that can trap extremely small particles as small as 0.3 microns in size
  • Highly effective at removing dust, pollen, pet dander, smoke, and other particulates from the air
  • Must be replaced regularly as they get clogged over time

Activated Carbon Filters

  • Contain a porous form of carbon that attracts and traps gases, odors, and volatile organic compounds (VOCs)
  • Excellent for eliminating cooking odors, smoke, and chemical fumes
  • Often used in conjunction with HEPA filters

UV Light Technology

  • Ultraviolet lamps are used to destroy microorganisms like bacteria, viruses, and mold spores
  • UV radiation damages and disrupts their DNA, eliminating them from the air stream
  • Helps prevent the spread of airborne illnesses and fungal growth

Many purifiers combine two or more of these technologies to target a wider range of indoor air pollutants. Higher-end models may also incorporate additional filters, sensors to monitor air quality, and smart functionality.

What Do Air Purifiers Remove From Indoor Air?

What Does an Air Purifier Do?
Pollen is one of the main reasons for using air purifiers in spring

Air purifiers are designed to remove a wide variety of common indoor air pollutants. Some of the main contaminants they can filter out include:

Dust and Dust Mites

  • Tiny particles of soil, fibers, dead skin cells that can trigger allergies and asthma
  • Dust mites that thrive in dust and shed allergenic proteins


  • Tiny airborne particles released by trees, grasses, and weeds cause hay fever

Pet Dander

  • Microscopic flecks of skin shed by cats, dogs, and other fur-bearing pets
  • A major allergen for people with pet allergies


  • Secondhand tobacco smoke as well as smoke from cooking, fireplaces, etc.
  • Contains harmful gases and particulates

Mold Spores

  • Reproductive spores released by mold that can cause allergic reactions
  • Allows mold growth if humidity levels are high

Volatile Organic Compounds (VOCs)

  • Gases emitted from household items like paint, aerosol sprays, cleaning products
  • Can cause headaches, nausea, and respiratory issues


  • Gets rid of stubborn cooking smells, pet odors, and other unpleasant scents

In addition to particles and odors, some purifiers also target other contaminants like:

  • Bacteria and viruses
  • Chemical fumes and vapors
  • Radon and other radioactive particles

By removing these pollutants from the air, purifiers can significantly improve indoor air quality and reduce triggers for allergies, asthma, and other respiratory conditions.

Benefits of Using an Air Purifier at Home

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Air purifiers are quite helpful

Using an air purifier in your home offers numerous benefits for your health, comfort, and well-being. Here are some of the key advantages:

  1. Reduces Allergy and Asthma Symptoms By removing triggers like dust, pollen, pet dander, and mold spores from the air, purifiers can provide relief for allergy and asthma sufferers. This allows for easier breathing.
  2. Eliminates Unpleasant Odors The activated carbon filters absorb odors from smoke, pets, cooking and more – leaving indoor spaces smelling fresh and clean.
  3. Removes Airborne Toxins and Chemicals
    Purifiers capture volatile organic compounds (VOCs) and other toxic chemicals released from household products, preventing them from circulating indoors.
  4. Improves Sleep Quality Cleaner, purified air can reduce instances of coughing, sneezing and congestion caused by allergens – allowing for deeper, uninterrupted sleep.
  5. Reduces Dust Buildup By filtering out dust particles, purifiers minimize the amount of dust that accumulates on surfaces, cutting down on cleaning time.
  6. Creates a Fresher Living Environment Overall, running an air purifier leads to a cleaner, more comfortable, and healthier indoor atmosphere to live and breathe in.

Long-term exposure to indoor air pollutants can potentially cause respiratory diseases, heart disease, and even cancer according to the EPA. Using a quality air purifier is an effective way to safeguard your home from these contaminants.

Study after study has shown that the levels of many pollutants can be higher indoors than outdoors.American Lung Association

By improving your indoor air quality with a purifier, you’re taking an important step toward protecting your family’s health and well-being.

Things to Consider When Buying an Air Purifier

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Better purifier’s placement is critical – Image credit

With so many air purifier models on the market, it can be difficult to determine which one is best suited for your needs. Here are some key factors to consider when selecting an air purifier:

  1. Room Size and Coverage Area Air purifiers are rated by the maximum square footage they can effectively cover. Choose a model that can handle the square footage of the room(s) where you plan to use it.
  2. Filter Types and Replacement Costs HEPA filters need regular replacement every 6-12 months, while carbon filters may last 3-6 months. Consider long-term filter replacement costs.
  3. CADR Rating CADR (Clean Air Delivery Rate) measures how effectively a purifier captures pollutants. The higher the CADR, the more particles are removed.
  4. Noise Levels Some purifier fans can be quite loud, especially in higher settings. Check noise ratings if you’re sensitive to sound.
  5. Additional Features More advanced models include features like air quality sensors, smart connectivity, ionizers, automatic modes, remote controls, and more.
  6. Energy Efficiency Running an air purifier 24/7 can increase energy costs. Look for Energy Star-certified models that are more efficient.
  7. Filter Replacement Indicator This handy feature alerts you when it’s time to replace the filter(s) based on usage, saving you from guesswork.

Considering these factors allows you to select the best purifier that meets your specific home’s needs, space requirements, and budget constraints. Don’t just buy the cheapest – investing in a quality purifier pays off.

Doing thorough research upfront ensures you get an air purifier that will effectively clean your indoor air for years to come.

Do Air Purifiers Really Make a Difference?

With all the claims made by air purifier manufacturers, you may be wondering if these devices actually live up to the hype. Do air purifiers genuinely improve indoor air quality, or is it all just marketing fluff?

Numerous scientific studies have validated the effectiveness of air purifiers when used properly:

Case Study 1: A 2018 study published in the Journal of Asthma found that using HEPA air purifiers significantly reduced levels of particulate matter, dust mite allergens, and airborne mold in homes of children with asthma over a 12-month period.

Case Study 2: Research by the University of Minnesota found that high-efficiency particulate (HEPA) filters were able to remove over 99.9% of particulates and allergens like dust, smoke, pollen, and pet dander from indoor air.

Case Study 3: The EPA conducted tests showing quality air purifiers were able to lower indoor particle levels by over 85% in just a matter of hours after being turned on.

Real-world examples and tests by independent reviewers have also demonstrated the tangible impact air purifiers can have:

After running this air purifier in my living room for 6 hours, I could physically see the air looked cleaner and crisper. My husband’s allergies also cleared up.” –Wirecutter Review

We measured our indoor air quality before and after using the purifier. After just 1 day, the PM2.5 particle levels dropped from 35 ug/m3 to just 3 ug/m3 which is considered excellent.” – Smart Air Review

Of course, results can vary based on factors like the purifier model, room size, type and concentration of pollutants, length of use, and more. However, the overwhelming body of evidence shows high-quality air purifiers absolutely can and do substantially reduce indoor air pollution when used properly as part of a home clean air strategy.

Still not convinced? See the impact for yourself by tracking indoor particle levels with an air quality monitor before and after running a purifier.

Proper Use and Maintenance of Air Purifiers

To get the most out of your air purifier and maximize its effectiveness, it’s important to follow some best practices for proper use and maintenance:

Optimal Placement

  • Place the purifier in the room where you spend the most time
  • Locate it at least a few feet away from walls and corners
  • Avoid blocking the air intake and outflow vents
  • Run it with windows and outside doors closed for best results

Operating Tips

  • Run the purifier 24/7 for continuous air cleaning
  • Use higher fan speeds for quicker air circulation
  • Close off unoccupied rooms to concentrate cleaning power
  • Open interior doors to allow airflow between rooms

Filter Maintenance

  • Check filters regularly and replace them per the manufacturer’s schedule
  • Use genuine replacement filters from the same brand
  • Vacuum off reusable pre-filters to remove large debris

Proper Cleaning

  • Unplug the unit before any cleaning
  • Wipe down the exterior with a dry microfiber cloth
  • Never use water or cleaners inside the unit
  • Check for any obstructions in the intake and outtake vents

Using Other Methods for Even Better Indoor Air Quality:

  • Vacuum frequently using a HEPA filter vacuum
  • Use exhaust fans when cooking
  • Increase ventilation by opening windows periodically
  • Control humidity levels to prevent mold growth
  • Remove sources of smoke or chemical fumes

By carefully following usage instructions, maintaining filters, and integrating other cleaning methods, you’ll extend the life of your air purifier while optimizing its air-cleaning performance.


In summary, air purifiers work by drawing in contaminated indoor air, filtering it through various purification technologies, and releasing cleaner air back into the room. The filtration systems target a wide range of pollutants like dust, pollen, smoke, odors, chemicals, and more.

Using an air purifier provides substantial health benefits by reducing allergy and asthma triggers, removing airborne toxins, and creating a fresher, cleaner overall indoor environment. When selecting a purifier, consider factors like room size, filter types, noise levels, and smart features.

Numerous studies and real-world examples have proven that high-quality air purifiers can significantly improve indoor air quality when used and maintained properly as part of a clean air strategy.

By following best practices for operation, filter changes, and integrated cleaning methods, you can ensure your air purifier is working effectively to continuously clean the air in your home. Breathing easier starts with purifying the air around you.


FAQs (Frequently Asked Questions)

Q: Where is the best place to put an air purifier?

For optimal results, place the air purifier in the room where you spend the most time, like a living room or bedroom. Position it at least a few feet away from walls, corners, or obstructions so air can circulate freely. Run it with doors and windows closed.

Q: How long should you run an air purifier?

It’s recommended to run your air purifier 24 hours a day, 7 days a week for continuous air cleaning. Use higher fan speeds when you need to quickly circulate and purify the air after cooking, dusting, etc.

Q: How often do air purifier filters need to be changed?

Most HEPA filters should be replaced every 6-12 months, while carbon filters may need replacement every 3-6 months. Check your model’s manual and look for filter replacement indicator lights.

Q: Do air purifiers produce ozone?

Most modern air purifiers are ozone-free and do not use ozone as a purification method, as ozone itself is an indoor air pollutant. Look for models that generate little to no ozone emissions.

Disclaimer: The views and opinions expressed in this review are based on the author’s personal experience and research. Individual results may vary. Always refer to the manufacturer’s guidelines and instructions for proper usage and maintenance of the product.


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