How Do Air Purifiers Work? (Everything You Need to Know)

Are you interested in the technology behind air purifiers?

More specifically, are you wondering how do air purifiers work?

If so, this detailed guide is for you.

Below, we’ll explain everything you need to know about how air purifiers operate to clean indoor air.

The truth is that each air purifier model works differently depending on the filtering process it uses to extract airborne pollutants.

Some air purifiers may only use one type of air cleaning technology while others use three or four or more.

To find out what those technologies are, how they work, and to figure out which type is best for you, keep reading.

1. HEPA Air Purifiers

The acronym “HEPA” stands for High-Efficiency Particulate Air.

And a HEPA air purifier is one that uses a HEPA filter.

A HEPA filter gets its name by meeting a strict standard set by the U.S. Department of Energy and the European Committee for Standardization.

As long as the air filter can trap particles that are 0.3 micrometers or larger at a rate of 99.97% efficiency, the type of material that it’s made of doesn’t matter.

A HEPA filter must also let a specific amount of airflow through it. It can’t block every particle and the air from passing through the filter medium, otherwise, it wouldn’t be a filter.

An air purifier that uses a HEPA filter sucks indoor air through the machine, traps the harmful pollutants in the filter, and lets clean air pass through the other side.

HEPA filters are great for removing airborne particles such as dust, allergens, pet dander, visible smoke, and some bacteria.

You can find a list of the best HEPA air purifiers on our top rated air purifier list.

2. Ionizer Air Purifiers

An air purifier that uses an ionizer operates much differently than a HEPA filter.

Ionizers don’t use a filter medium to trap airborne contaminants.

Instead, these machines function in one of two ways to extract pollutants out of the air:

  • By emitting charged ions out into the air to latch onto floating pollutants.
  • By charging a set of plates that collect pollutants on a surface.

If the ionizer emits ions into the air, no filter or collection plate is located on the machine. It just spreads out charged ions that attach to airborne contaminants.

Once these bonds occur, the pollutants get weighted down and fall out of the air.

If the ionizer uses a set of charging plates, it’s technically called an “electrostatic precipitator”.

No ions are emitted into the air. Instead, this machine uses a fan and motor to draw air through the device where molecules that pass through either pick up an additional electron, giving it a negative charge, or have an electron knocked off, giving it a positive charge.

An electrostatic precipitator has both negative and positive charged plates that cause the molecules to stick to them.

Over time, these plates get filled up with contaminants and must be washed clean for them to stay effective.

Ionizers and electrostatic precipitators can get rid of the same types of pollutants as HEPA filters; however, these particles are not trapped inside a dense filter.

With an ionizer, the particles still linger in the room and must be vacuumed up to completely remove them.

The advantage here is that these machines are cheaper to buy and maintain since they don’t use degradable filters.

To see what’s available in this type of air purifier, check out our best ionic air purifier list.

3. Activated Carbon Air Purifiers

How do air purifiers work to remove odors?

The secret is with an Activated Carbon filter.

Air purifiers that include Activated Carbon filters are the only type that can eliminate airborne smells, gases, chemicals, and fumes.

And they do this through a process called “adsorption”.

Adsorption is where one substance gets trapped on another substance’s surface. One of the most common adsorbent agents is activated carbon (also known as activated charcoal).

Activated carbon is very porous with hundreds of microscopic areas that effectively trap passing molecules.

Contaminants that pass through an Activated Carbon filter adhere to the surface material and this prevents them from returning back to the air.

These filters are the best defense against indoor odors from all sorts of things, like paints, varnishes, pets, cooking, mold, diaper pails, etc.

They’re also great for personal workspaces inside an office. Many building materials and office equipment emit odors and volatile organic compounds which can harm your health.

To stay safe, you can use a small desktop air purifier to keep the air around you clean.

Check out our best air purifier for office desk list to find out what features to look for in a high-quality air cleaner of this type.

4. Ultra Violet Air Purifiers

These air purifiers have a much different use than the types previously mentioned.

Ultra Violet air purifiers create a sterile environment by using a short-wave UV-C light to put airborne pathogens and microorganisms into an inactive state.

This process of “light bathing” is what kills bacteria and viruses that pass through the air purifier.

It does this by altering the DNA structure to render these particles harmless.

No other type of air purifier works this way. Only Ultra Violet air purifiers can sterilize an indoor environment.

5. Ozone Air Purifiers

Ozone air purifiers work similarly to Ionizers but instead of sending out charged ions into the air, these machines work by altering oxygen molecules to turn them into ozone.

Standard oxygen only has two oxygen atoms (O2) in its makeup.

When oxygen is split by an Ozone air purifier through corona discharge or ultraviolet radiation, the molecules turn into single atoms.

Some of those atoms reform with three oxygen particles (O3) which is called ozone.

The newly formed ozone floats throughout the air and attaches to contaminants like dust, smoke, and organic matter such as viruses, bacteria, and mold spores.

Ozone air purifiers can also deodorize the air.

Unfortunately, ozone also reacts with any other chemicals in the air which can cause things like oxidized metal or corrosion.

The bad thing about Ozone Generators is that they’re not good for human health. Breathing in ozone can cause a number of short and long-term health issues.

So, it’s best to only use Ozone generators when people are not present inside the home when these machines are being used.


You now know the five ways for how do air purifiers work.

As we mentioned in the introduction of this page, air purifiers come in all different types.

Some products may include just one of these air cleaning technologies while others may include two, three, or more.

When it comes to cleaning indoor air, air purifiers are an excellent device to strip out the pollutants.

By running one of these devices in your home and office, you can breathe cleaner, fresher air each day.