a graphic showing whether air purifiers are worth it

Do Air Purifiers Work? A Clear Guide

by Karl von Luckwald / January 25, 2024

Air purifiers are supposed to catch pollutants and improve indoor air quality. But do air purifiers work?

Air pollution is invisible. So, how can you tell if your air purifier supposed what he’s doing or if it’s just a waste of money?

In this article, we’ll talk about if air cleaners are a good choice. We’ll see how they work, and what science says about them. Eventually, we’ll do a real-world test to check whether air cleaners actually purify the air.

So, do air purifiers work?

Yes, air purifiers work and the scientific evidence is pretty conclusive. Air purifiers are particularly effective against dust, pollen, smoke, pet dander, viruses, and bacteria, improving overall air quality

What Does an Air Purifier Do?

Air purifiers clean the air of harmful things, which is good for your health.

Those with HEPA filters are good at catching tiny dust like PM2.5. With one at home, you can have clean air inside, even if there’s bad smog outside.

The Sqair with beautiful design next to a couch in a living room
Air purifiers are supposed to improve indoor air quality

In places like Asia, where air pollution is really bad, almost everyone has an air purifier. After COVID and more wildfires, they are now common in Western countries too.

How Do Air Purifiers Work?

Air purifiers are pretty simple to understand and work on an easy principle. They have a fan and a special filter called a HEPA filter.

Here’s how they work: the fan pulls in the air that’s not clean, the filter catches the dirt and stuff from the air, and then the air that comes out is much cleaner.

a graphic of an opened iq air air purifier showing it contains a fan and a filter
Air purifiers are simple and consist of little more than a fan and a HEPA filter.

Air purifiers trap airborne pollutants. Here’s a list of things they can filter out of the air:

  • PM2.5 (Fine Dust)
  • Viruses
  • Bacteria
  • Dust mites
  • Pollen
  • Pet dander
  • TVOCs (Total Volatile Organic Compounds)

What Does the Science Say?

Now, let’s look at the truth. Do air purifiers work, or are they just another tech gadget?

To figure this out we need to know that different air cleaners use different ways to clean the air. The most common ones are:

  • HEPA air purifiers
  • Air purifiers with activated carbon filters
  • Ionizers
  • UV light air purifiers

Next, let’s see what science says about them.

Science and Air Purifiers

HEPA Air Purifiers: How Effective Are They?

During the COVID-19 pandemic, a lot of people talked about air purifiers.

The Otolaryngology Journal, a big health journal in the US, looked at 11 studies about them. All these studies said that air purifiers with HEPA filters (High-Efficiency-Particulate-Air) can cut down on tiny airborne viruses, like the Coronavirus.

Sqair opened with a HEPA filter
Air purifiers containing HEPA filters filter all kinds of airborne pollutants

How HEPA Air Purifiers Work

HEPA filters are a simple invention from about 80 years ago. They’re made of synthetic fibers randomly woven together.

In an air purifier, the HEPA filter is put in front of a fan. The fan sucks in dirty air and pushes it through the filter. The filter catches all the bad stuff and lets clean air go through.

microscopic view of a hepa filter showing thousands of fibers
A microscopic view of a HEPA filter: thousands of fibers trap pollutants

HEPA filters like a very fine net that traps everything from big dust and pollen to tiny particles much smaller than a human hair. NASA even found that these filters can catch nearly 100% of pollutants in the air.

Ionizers in Air Purifiers: Do They Help?

In the past ten years, many companies started putting ionizers in their air purifiers.

Ionizers send out negative ions. These ions stick to airborne pollutants which are positively charged. The dust then falls on things like desks or floors.

a graphic showing how ionizers work by sending out negatively charged ions that attract positively charged particles
Ionizers in air purifiers attract airborne particles and drop them onto surfaces

Ionizers don’t trap the dust like a HEPA filter does. They just move it around. So, their real value is a bit uncertain.

There are two major issues with ionizers.

One, they can make things dirty because the dust sticks to surfaces.

an air purifier with ionizers gets dirty
A Blue Air air purifier with an ionizer: dust sticks on surfaces

Two, some ionizers produce ozone as a byproduct, which is not good for our lungs. A study by the University of Texas showed that ionizers even produce PM2.5.

Knowing this, I wouldn’t recommend ionizers, especially since HEPA air cleaners are good enough on their own.

UV Light Air Purifiers: Effective or Not?

With the COVID-19 pandemic, air purifiers with UV lights became popular.

These purifiers use UV lights to neutralize viruses. However, this might not be as effective as it sounds.

Although UV lights can inactivate microorganisms including, bacteria and viruses, those added to air purifiers are too weak to have a significant effect.

This is because too strong UV is harmful to our bodies. Just think of your last sunburn.

Furthermore, some UV air purifiers emit Ozone like ionizers do. This is why the EPA is not recommending them.

a close up shot of blue uv lights
UV air purifiers are too weak to have a significant effect

Real World Test

After learning about air purifiers scientifically, I decided to test one myself.

I turned my bedroom into a little lab.

First, I burned an incense stick to create artificial air pollution. I used my QP Pro air quality monitor to check pollution levels.

an air purifier in a bedroom next to an air quality monitor and a lit incense stick
Lighting an incense stick creates PM2.5

Right after lighting the incense, the PM2.5 level jumped to 107 micrograms per cubic meter. That’s way over 10 times the safe limit set by the WHO.

Then, I switched on my Sqair air purifier, which has a HEPA filter. It’s good for rooms up to 40 square meters, and my bedroom is about 25 square meters.

an air purifier in a bedroom next to an air quality monitor showing high levels of indoor air pollution
After lighting the incense stick PM2.5 spiked by almost 1000 percent

In 10 minutes, the air quality got 25% better. In 20 minutes, 60% of the pollution was gone. After 35 minutes, the pollution level was down to 8 micrograms per cubic meter, which is safe.

Within 35 minutes, the Sqair cleaned out all the bad particles in the air.

a graphic showing how air pollution improved in the bedroom after turning on the air purifier
Within 35 minutes the air purifier brought air quality to a safe level

Learn more about the best air purifiers available in the market.

Are Air Purifiers Worth It?

Alright, let’s come to the core questions of this article: are air purifiers worth it?

We found that air purifiers with ionizers or UV lights might not be the best. But those with HEPA filters are good at cleaning the air. Both science and our test prove this.

So, yes, air purifiers with HEPA filters do work! If you have asthma or allergies, live in a polluted area, or are around germs a lot, you should think about getting one.


Air purifiers have been proven to work well and filter airborne pollutants. People living in polluted areas or suffering from allergies/asthma should consider buying one.

Health Benefits of Air Purifiers

Every year, about 7 million people die because of long-term exposure to air pollution. Air purifiers help protect us from breathing this harmful air.

Research from Yonsei University has provided compelling evidence for the effectiveness of air purifiers in reducing the need for medication among individuals with allergies.

They are also beneficial for people suffering from asthma. Studies from Korea have shown that air purifiers can ease asthma symptoms and bring comfort.

Having better air quality inside your home has many health benefits. It can lower the risk of respiratory problems, strokes, and lung cancer.

Air filters furthermore can help you sleep better, have more energy, and think more clearly. This is especially helpful for people with health issues, kids, and older adults.

Finding The Right Air Purifier

It’s very important to choose the right air purifier to keep the air inside your home healthy.

The most expensive air purifier might not be the best for you. Look for key features like HEPA filtration, the right size for your room, and how well it cleans the air.

To figure out whether your air purifier can keep up with your room size, look for the CADR rating (Clean Air Delivery Rate). The higher the number the stronger the air purifier.

Informing about noise levels and energy usage is recommended too.

Also, taking care of your air purifier and knowing the costs to keep it running is important for being happy with it over time.

Bottom Line

Air purifiers, especially those with HEPA filters, are worth it. They effectively clean indoor air by removing harmful pollutants like dust, viruses, and allergens. This makes them particularly beneficial for people with allergies, asthma, or those living in areas with high pollution. When choosing one, focus on key features like HEPA filtration, room size compatibility, and energy efficiency for the best results.


Yes, air purifiers make a significant difference. The test showed that a HEPA air purifier drastically improved air quality, reducing PM2.5 pollution from hazardous levels to safe levels within 35 minutes.

Absolutely. Air purifiers are beneficial, especially for those with allergies, asthma, or living in high-pollution areas. They effectively clean indoor air, reducing health risks associated with air pollution.

The main disadvantages include the cost of purchase and maintenance, potential noise, and, in the case of some types like ionizers and UV purifiers, the limited effectiveness and possible emission of ozone.

Yes, an air purifier is still beneficial even if you have AC. While AC regulates temperature, air purifiers are effective at removing a wider range of airborne pollutants, including fine particles and allergens.

Karl von Luckwald

Karl von Luckwald

Since moving to Thailand in 2019, Karl noticed the lack of scientific integrity in air purifier and water filter reviews. In response, he founded WE DO AIR to champion unbiased, science-based evaluations and empower consumers to make better-informed decisions.

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