Good air purifiers should be able to trap airborne allergens, fight germs, and remove odor. But how do they do it? If you’ve been pondering that question, rest at ease. In this article, we’re going to tell you the basics of how an air purifier works.

how an air purifier works

So, the basis of all purifiers is to pull in dirty air, clean it up, and push clear air back out. That’s the gist of it. How they do the second process, however, can differ from one model to another. In the market, you can find filter and filterless air purifiers. Let’s discuss how each work in more detail.

How Filter Air Purifiers Work

Most filter purifiers in the market use High-Efficiency Particulate Air (HEPA) filters. A true HEPA filter can trap 99.97% of airborne particles as small as 0.3 microns. Just for the record, one micron is one a millionth of a meter.

how does air purifiers work

Once the dirty air is sieved through the filter, the fan pushes the clean air out.

While true HEPA filter is the most popular choice, there are also purifiers that use HEPA-type filters. These kinds of filters can only trap 99% of particulates.

They are generally less effective compared to purifiers with true HEPA filter, but still useful for reducing dust in your home.

On some purifiers, clean air that has gone through the HEPA filter is then pushed to a carbon filter.

Why, you ask?

Well, the main job of a carbon or charcoal filter is to get rid of odors. A purifier with HEPA filter alone cannot remove odor. An activated carbon filter has an extremely large surface area, which allows it to adsorb odor-causing particles effectively.

If you are a pet owner, exposed to cigarette smoke, concerned about molds, or a cooking enthusiast, a purifier with activated carbon filter will be a tremendous help.

It can keep your home smelling fresh no matter what.

air purifiers

Occasionally, the order of these two filters is reversed. First, dirty air goes to the carbon filter before going through the HEPA filter. In this arrangement, the carbon filter also acts as a pre-filter so as to prolong the HEPA filter’s life. One such purifier that uses this arrangement is the Germ Guardian 3-in-1 air purifier.

Some air purifiers go the extra mile and are equipped with a UV sanitizer that actively destroys bacteria and viruses. Such addition is especially useful during flu season.

How effective is UV light in handling bacteria? We’ll let this video do the talking:

How Filterless Air Purifiers Work

Filterless air purifiers usually employ negative ion generators, which uses high voltage to ionize air particles.

When the negative ion latches itself to dust, it weighs the dust down so it is no longer airborne. Purifiers of this type often have positively charged collecting plates where the dust gather.

how air purifiers workSome brands, like Airfree, uses hot ceramic core to obliterate dust, pollen, bacteria, viruses, and practically any airborne particles. The hot ceramic core goes up to 400o Fahrenheit. It takes 167o Fahrenheit to kill influenza virus, so 400o is a bit much. But if you want to be sure to get all those viruses and bacteria, going a bit extreme is sometimes necessary.


Okay, that’s it with our simple guide of how an air purifier works. Most of the purifiers you see in the market follow these setups. In most cases, an air purifier will only use one cleaning method, while more advanced ones combine two or more.

The Pionair 1500 air treatment system, for example, combines HEPA filter, activated carbon filter, UV sanitizer, and negative ion generator.

do air purifiers really work

Which air purifier should you pick then?

It all depends on your needs, of course. Whether you go with filter or filterless, we suggest you read our extensive guide so you can make a well-informed decision.