If you are like us you want to know whether an air purifier works.  The goal is have clean air in our homes or office.  So, it makes sense to see what works best in improving our indoor air quality.

That’s why we test.  A lot.

In this article we present some surprising findings from our testing.  We also include feedback from users of the product and research we have found on the subject.

The focus here will be on how well do air purifiers work for allergies, dust, pet allergies and smoke.

If you want to see the ratings of air purifiers you can see how well they work overall.


Allergies, Dust and Pet Dander

There is no escaping allergies and dust.  They are everywhere.  If you have pets you likely have pet dander from hair and feathers.

We have written a lot about allergies.  The bottom line is there is one type of filter that works best.

It is the HEPA filter.  As we explain in this article about HEPA filter efficiency, it uniquely removes both the small and large allergy particles.

This is important since allergies come in a variety of sizes.  The larger one’s settle to the floor relatively fast.  The smaller particles can take hours or days.  You really want to be able to remove both.

This leads us to the first interesting finding.

Finding #1

Pollen are particles.  So is dust, pet dander, and mold.  They have different particle sizes however it really doesn’t matter since a true HEPA filter can remove all of these.

In the chart below we show the particle sizes for a variety of items.  If you have a true HEPA filter it will remove 99.97% of all particles sized 0.3 microns and larger.

In our testing, we use a laser particle counter and measure each air purifier’s ability to remove these particles.  We found varying levels of performance.  You can see this in the efficiency rating that we give to each air purifier.

What is also amazing is that the efficiency can further improve for particles smaller than the 0.3 micron size.



What do air purifiers help with


A common use of air purifiers is in the removal of smoke.

If you want to learn more about smoke air purifiers we have written a bit about them.

Finding #2

What is interesting about smoke is that it is made up of both particles and gases.  In fact, hundreds of gases.

Smoke is hard to remove.  The reason is because you need multiple technologies to remove it.

While we tout HEPA for the removal of allergies, pet dander, mold, etc the fact is it is not good with odors.  It’s pretty terrible.

Odors are gases.  They will pass through a HEPA filter.  It’s like trying to catch water in a strainer.  It can’t hold it.  And if it does it will likely release it later.

The solution for this is activated carbon.  Usually the higher quality and more of it the better.

Although, what we saw in our testing is that an air purifier with a lot of carbon can also have reduced air flow.  You want to make sure there is enough air flowing through the air cleaner for your size room.

The metric for this is called CADR.  It relates to how much filtered air you will get out of the air cleaner.



Besides smoke we have read several customer reviews about the need to remove odors.


Finding #3

Odors are complex.  These gases can be so small and tricky.  What works well for one may not work well for another.

The standard filter method is carbon.  For most gases carbon does a great job.

But for some, like formaldehyde it is not so good.

Formaldehyde is commonly found in building materials.  Think particle boards.  Sometimes it can be in wood flooring.

To remove this requires other filter media.  The most common is called potassium permanganate.

When combined with activated carbon you have a powerful odor remover.



In this article we address whether air purifiers work.

We focused on the areas where air purifiers can work really well.  And highlighted some areas where they are not so effective.

There are other air purifier technologies that we did not discuss since in our testing they did not perform as well.