The Workings of an Air Purifier Made Easy

How Does an Air Purifier Work

An air purifier works by drawing in air from the surrounding environment and passing it through a series of filters to remove pollutants, allergens, and other harmful particles before releasing the cleaned air back into the room. The specific filtration process may vary depending on the type of air purifier, but most use a combination of filters to trap particles of different sizes.

The first stage often involves a pre-filter that captures larger particles like dust, pet hair, and lint. The air then passes through a primary filter, such as a HEPA (High-Efficiency Particulate Air) filter, which can trap smaller particles like pollen, mold spores, and even some bacteria and viruses. Some air purifiers also include an activated carbon filter to absorb odors, gases, and volatile organic compounds (VOCs).

In addition to filtration, some air purifiers use other technologies to enhance their air-cleaning capabilities. For example, some models incorporate UV-C light to kill germs and bacteria, while others use ionizers to charge particles, causing them to clump together and become easier to filter.

As the air purifier continues to operate, it constantly circulates and filters the air in the room, gradually improving the overall air quality. Many modern air purifiers come with smart features like app control or built-in air quality sensors that can detect and display the current Air Quality Index (AQI) in real-time.

Key Takeaways

  • Intake – Air purifiers draw in surrounding air through an intake grill.
  • Filtration – Air passes through one or more filters.
  • Air circulation – Cleaned air is released back into the room, continuously improving air quality.
  • Effectiveness – Depends on factors like room size, air changes per hour (ACH), and filter quality.
  • Additional technologies – Some purifiers use UV-C light to kill germs or ionizers to charge particles for easier filtration.
  • Smart features – Many modern purifiers include air quality sensors and app controls for monitoring and adjusting performance.

Overview of the Workings of Air Purifiers

Overview of Air Purifiers

Air purifiers are devices that are designed to filter and purify the indoor air within a defined space. Their primary job is to reduce the concentration of airborne contaminants, improving the overall indoor air quality. They come in various shapes and sizes, designed for different room sizes, and with a range of specific air purifying functionalities, from basic dust and pollen removal to the more comprehensive elimination of bacteria and viruses.

Curiosity got the better of me one weekend when I decided to take apart my old air purifier that had stopped working. Armed with a screwdriver and my limited knowledge of electronics, I carefully removed the outer casing. To my surprise, the inside was less complicated than I’d imagined.

The main components were a fan, a motor, and several layers of filters. I discovered that the fan drew air in through the front, pushing it through increasingly fine filters – from a pre-filter for large particles to a HEPA filter for microscopic pollutants. There was even a small, activated carbon filter for odors. The motor, connected to the fan, was what had failed in my unit.

Types of Air Purification Filters

How Does an Air Purifier Work
  • Air Filtration – Air filtration is the backbone of air purification. HEPA (high-efficiency particulate air) filters are what trap the majority of allergens, dust mites, mold spores, and pet dander to improve air quality. They’re so effective that, in combination with the other filtration methods, some air purifying devices can capture particles as small as 0.3 microns, which, to put into perspective, is about 30 times smaller than a human hair strand.

  • Activated Carbon Filters – Carbon filters in air purifiers deal with the larger, more organic pollutants that are usually the sources of odors—think tobacco smoke, cooking smells, and pet odors that impact indoor air quality. As these pollutants come into contact with the activated carbon filter, they bond to the surface, effectively scrubbing the air of unwanted smells and potentially harmful substances.

  • UV-C Light – Ultraviolet light, particularly the UV-C variety, is known for its ability to disrupt the DNA of pathogens, such as bacteria and viruses, rendering them unable to reproduce. Air purification systems with UV-C lamps can destroy microorganisms by using short-wavelength UV light to kill or inactivate microorganisms by destroying nucleic acids and disrupting their DNA, thus improving air quality.

  • Ionization – Many air purifiers use ionizers to give particles an electrical charge. As these ionized particles flow back into the room, they become attracted to oppositely charged surfaces, which usually include the collectors of the air purification system. This can be especially useful for those ultrafine particles that might otherwise slip through the HEPA filter in an air purifier. In the room, they become attracted to oppositely charged surfaces, which usually include the collectors of the air purifier. This can be especially useful for those ultrafine particles that might otherwise slip through the HEPA filter.

Components of an Air Purifier

  • Fan – The heart of the air circulation system
  • Filters – Various types for particle removal and air sanitization
  • Housing – The exterior casing that contains all components
  • Control panel – For user interface and settings adjustment

Air Intake Process

The air purification cycle begins with the intake process. The fan, acting as an air mover, draws in ambient air through strategically placed vents. This suction creates airflow, pulling in dust, pollen, and other airborne particles.

Filtration Stages


  • Captures larger particles like dust and hair
  • Protects subsequent filters from rapid clogging

HEPA filter (High-Efficiency Particulate Air)

  • Traps 99.97% of particles as small as 0.3 microns
  • Key component in particle filtration and allergen removal

Activated carbon filter

  • Adsorbs odors, smoke, and volatile organic compounds (VOCs)
  • Essential for gas and chemical filtration

Other Types of Filters

  • UV light for germicidal irradiation
  • Ionizer for electrostatic precipitation of particles

Air Output

After passing through the filtration stages, the purified air is released back into the room. Proper placement of the air purifier ensures optimal air circulation and distribution of clean air throughout the space.

Features That Some Air Purifiers Have

Air Purifier with Air Quality Detectors

These devices use built-in sensors to continuously monitor the air for pollutants such as dust, pollen, and harmful gases. When the sensors detect a rise in air pollution levels, the purifier automatically adjusts its cleaning power to address the issue. Many smart purifiers display real-time air quality information on a screen or through a mobile app, allowing users to track air quality trends over time.

Air Purifiers That Tell Your When to Change the Filter

These devices typically use sensors or timers to track filter usage and air quality. When the filter becomes clogged or reaches its recommended lifespan, the purifier sends a notification, often through a light on the device or a message on a connected app.

Frequently Asked Questions

Q. Are their air purifiers without a filter?

A. Yes, some air purifiers use technologies like ionization that create negative ions to make dust and other particles stick to surfaces, improving indoor air quality without relying solely on physical air filtration methods. However, it’s worth noting that while filterless methods can be effective for certain types of pollutants, they may not be as comprehensive as traditional filter-based air purifiers in removing a wide range of contaminants from the air.

Q. Are air purifiers worth it?

A. Yes, they are if you have issues with allergies, dust build-up in your home, mold issues, or if you just want to breathe clean fresh air.

Q. Can an air purifier reduce dust?

A. Yes, if the air purifier is capable of handling the space. Most purifiers remove between 30% – 80% of the total dust in a room, but this also depends on the strength of the air purifier and the quality of the filter.

Q. An air purifier does what?

A. Air purifiers are designed to clean the air of particles like dust and dander from the air as well as odors and some can kill viruses and bacteria.

Q. Do air purifiers work for allergies?

A. Yes, air purifiers with a HEPA filter will help because HEPA is designed to remove allergens from the air.

Q. Do air purifiers work for mold?

A. Yes, air purifiers with a HEPA filter remove mold spores from the air.


Air Purifiers Fact Sheet | Environmental Health & Safety – UMass Amherst

Frequently asked questions about air cleaners –

Residential Air Cleaners –

Guide to Air Cleaners in the Home –

Air Cleaners and Air Filters in the Home –

Joel Simon

Joel, a seasoned blogger with a passion for home products, has been making waves in the digital realm for the past seven years. With a knack for crafting insightful reviews and informative posts, He has become a trusted voice in the world of home improvement and lifestyle blogging.

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