How Does an Air Purifier Work? Do You Need An Air Purifier?

In spite of its plain look, an air purifier can do quite a lot of things, and its working mechanism is also quite complex yet interesting. 

Let’s learn how an air purifier works, what it actually does, and why you should use it before you buy an air purifier. Just spending a few minutes surely helps you much!

How an air purifier works
How an air purifier works

How Does An Air Purifier Work?

Basically, regardless of air purifying technologies,  the main components of home air purifiers that take part in the air purification process just include the fans and filtration system. Thus, there we will solely learn about how they work to clean air.

Fans pull pollution particles in

Inside electronic air purifiers, there are fans that are responsible for pulling the dirty outdoor air and air pollutants in it (e.g., dust, pet dander, or pollen) into the device to purify and then blowing the purified air out. 

Most models enable users to set various fan speeds. The faster the fans spin, the more quickly the air purifier works, but the more noise it produces, and vice versa.

Filters eliminate particles 

There might be several filters in an air purifier
There might be several filters in an air purifier

The majority of air purifiers utilize mechanical air filters that are good at capturing particles as the air is pulled through by fans. The two primary kinds of filters consist of a pre-filter and a true HEPA filter

The air cleaning mechanism of each filter is as below:


  • Pre-filter


Pre-filters are put before the main filters to catch big particulate matter such as human hair or pet fur, and only leave fine particles/ultrafine particles like bacteria and viruses, mold spores, or dust mites

Similar to filters in an air conditioner, most pre-filters are disposable, only a few of them are washable. Therefore, pay attention to them and replace/wash them according to the recommended timeline by experts and the manufacturers.


  • True HEPA filter


After the air passes the first layers of filters remove airborne particles, cleaner air will go through the second air filtration process in the air system.  

The standard for the primary filters is an effective HEPA filter. True HEPA filters can trap particles and remove particles from 0.3 microns in size or above. 

HEPA filters are actually constructed from numerous layers of fiberglass threads. Then, the biggest particles will crash into them. Smaller ones will stick to them while the microscopic ones may zigzag through some fibers until they are trapped in the next fibers. 

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However, notice that some devices are not completely airtight or just feature “HEPA-type” or “HEPA-like” filters instead of HEPA or “true HEPA” ones. They have the same mechanism but inferior performances in improving home air quality to a HEPA air purifier.


  • Carbon filters


Apart from the two filters above, some models are equipped with extra activated carbon filters to absorb gases and odors. Sadly, this type of air filter only alleviates a certain number of gaseous pollutants but not all.

Some other types of air purifiers

There is not only one type of air purifier, but some of the following air cleaning technologies are also quite common, too.


  • Ionizers (ionic air purifier)


Some types of air purifiers work by using electrostatic precipitating to tackle ionic air rather than mechanical filtering. 

When the air in your home flows through them, particles from the air are charged and thus attracted to opposite-charge ions or to a collection surface.  

Then, these ion pairs will settle on the floor, furniture, or walls where you can use a vacuum cleaner to clean. This process can be called air ionization, which is quite similar to how salt lamps work.


  • UV light


There are portable air purifiers using UV lamps to kill microorganisms such as mold, bacteria, and gaseous pollutants in the air flow that go through the equipment.

However, these portable air purifiers do not work as well as they may sound since the level of UV light they generate and the duration that pollutant particles are trapped in the device are typically insufficient for the germicidal irradiation process to take much effect.  

Besides, deactivated and dead particles can still cause irritation and airborne allergens, so a HEPA air filter is in need. 


  • Ozone generator


Simple as its names, this appliance produces Ozone to react with and alleviate chemicals, mold, mildew, and bad odors in your home air. Plus, the natural smell of Ozone is very fresh, which makes users feel the air clean.

Cautions: All of the three types of air purifiers that we introduce in this section (Ionizers, UV light, and Ozone generators) emit Ozone. 

This substance actually purifies the air by reacting with and breaking down everything it contacts, including tiny cells inside the bodies of humans and animals. 

Therefore, they are scientifically proven to pose bad health effects on humans and pets in the long run and are not recommended using.

For a more intuitive explanation on “How does an air purifier work”, you can watch this video.

What Does An Air Purifier Actually Do?

An air purifier will turn dirty air into clean air
An air purifier will turn dirty air into clean air

Different from air cleaners that are intended for cleaning the air from big particles like dust, air purifiers are essentially used for purifying air, which means eliminating toxins, allergens, and pollutants. However, both of them are rated by CADR ratings (Clean Air Delivery Rate).

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Which particles are destroyed, transformed, or captured via an air purifier will vary depending on different models. 

For example, a HEPA air filter will trap all particles of a particular minimum size. Meanwhile, a negative ion emitting air purifier will neutralize positive ion particles. And adsorbent filters like activated carbon ones are engineered to handle gases such as radon or VOC (volatile organic compound). 

In fact, EPA (the Environmental Protection Agency) warns that air purifiers provide limited functionality on filtering harmful gases and users ought to wash or replace filters after around three months.

Why Should You Use An Air Purifier? 

Stay away from respiratory issues such as allergy or asthma

If you are an allergy sufferer with allergies and asthma or other respiratory matters, an air purifier with a HEPA (high efficiency particulate air) filter will reduce a lot of your symptoms, such as coughing and wheezing and coughing.

You raise pets

Most common pets that we raise at home may cause us pet allergy. Even when your dogs and cats that rarely shed can still release pollutants such as dust, pollen, and many more on their coats into the air. 

Moreover, even if you and your family members are not seemingly allergic to these animals, their fur can still pose other potential risks to your guests or clog up something else in the house.

Excellent air purifiers always have pre-filters to capture these large pieces of stuff, (e.g., human hair, pet fur, debris, and so on) before they make their way to the true HEPA filter. 

Also, charcoal or carbon filters will reduce uncomfortable scents from your pets, which your family may have got used to and feel normal, but your guests will not.

There are smokers in your house

Apart from its annoying smells,  tobacco smoke (especially secondhand one) is among the most prevalent pollutants from the air that badly affect the indoor air and the health of people who inhale it. 

According to scientists and thousands of researches, even the smallest amount of secondhand smoke in a well-ventilated area would still pose some risks to our health. 

In addition to ventilation, what you need is a filtration system. An air purifier with a HEPA filter can tackle super-fine particulates at the sizes of 2.5 micrometers, or PM 2.5.

Nevertheless, as we mentioned above, because not all air purifiers are good at filtering gas, you had better go for a model that is specialized for this field if cigarette smoke is exceeding in your home and is a great concern.

You live with the elders, kids, and other family members

Even when you are the cleanest man on earth who spends all day cleaning your house, if you live with many other people, especially children and elders, your home can hardly be clean enough for everybody to be always healthy. 

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While kids and older people are the most vulnerable by air pollution, they are also most likely to bring dirt, dust, pollen, and pet hair around the house. 

Hence, if you are living with these ones, an air purifier is a must to ensure your family’s health. 

Your residential air is not clean

If you are living in the city center or near a construction site, airborne pollutants like dust and exhaust fumes will attack your house heavily.

Mold, cement, asbestos, lead, and paint are very dangerous and can cause severe damage to parts of your body. And an air purifier can minimize those hazards.


After our article, you must have acquired a lot of useful knowledge on how an air purifier works to improve the indoor air quality. You should also consider whether buying an air purifying machine is necessary for you or not, and why.

Now, it is time to say goodbye and see you again in our next article. Anyway, thanks for reading!

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