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Do Air Purifiers Really Work?

Do air purifiers really work? The short answer is, yes. Air purifiers work to clean your space of dust, allergens, pollen, pet dander, airborne viruses, and improve your overall indoor air quality. But, there are factors to keep in mind when purchasing an air purifier to ensure it does effectively work for you and your needs.

To assess whether an air purifier will work for you it's important to know what you are looking to remove from the air, how sensitive you are to the pollutant, and the size of the space that needs cleaning.

In our experience, we have seen a fair amount of marketing hype with air purification systems since our founding in 2009. Our goal is to lay out the facts of air purifiers and be as objective as possible.


How Real HEPA Air Purifiers Work

At their most basic level, air purifiers are simple machines. They take in air, using a motor and fan to pull the air inward, and pass the air through a series of filters that remove a variety of contaminants, allergens, pet dander, and air pollution, such as VOCs - volatile organic compounds. They then push clean air out into the room.

Most HEPA air purifiers start with a pre-filter to remove the largest airborne particulates like pet dander or dust bunnies. This is the first filter that air will pass through, and it will remove a wide variety of large particles from the air.

“HEPA” is an acronym that stands for High-Efficiency Particulate Air, and it designates a filter that achieves a certain level of efficiency. To be classified as a HEPA filter, it must remove 99.97% of particles sized 0.3 microns from the air. This is an industry standard that is not enforced by the U.S. government, but it acts as a measuring tool for filter performance. If your air purifier has a HEPA filter, you can count on it to deliver extremely high filtration, which will result in cleaner air for you and your family.

Experts including the CDC, the EPA, Harvard, Johns Hopkins, and The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) agree that HEPA filtration is the proven and preferred technology for portable air purifiers.

What True HEPA air purifiers can and cannot do infographic


Choosing the Right Air Filtration Technology

Emerging technologies in the air purifier industry make a simplistic, effective, and trustworthy appliance more complicated. The only proven technology to improve air quality in the air purifier field is real HEPA filtration.

Real HEPA filters don't introduce anything new into your indoor air. Ionizers and ozone generators introduce ozone, a lung irritant, into your indoor air, which could have the exact opposite effect you want from your air purifier. You should avoid any air purifier that produces and releases ozone or other dangerous pollutants like hydrogen peroxide. The last thing you want is for an air purifier to introduce an air pollutant into your home.

There is consistent demand for filterless air purifiers or washable filters, but, in our experience, they are not as effective because they don’t remove as many airborne particles that contribute to indoor air pollution.

Air purifiers may use HEPA filters in combination with other technologies like activated carbon or UV-C lamps to target and eliminate specific problems, but the gold standard is real HEPA filtration and these other options won't be effective on their own.

Activated carbon is one of the top materials used in air purifiers in combination with HEPA filtration. Activated carbon filters focus on removing odors, chemicals, and smoke. Activated carbon filters can adsorb these gases and finer particles. If your main concern is cigarette smoke or wildfire smoke activated carbon and HEPA are the way to go.

UV-C light is another technology that is commonly used in air purifiers. UV light, which is a form of radiation, is able to destroy certain types of organic matter when exposed long enough to the UV rays. It can be used in combination with HEPA filtration to reduce airborne mold spores, which are a common form of indoor air pollution. But its effectiveness is entirely dependent on how long the particles are exposed to the UV-C rays. Air purifiers are constantly moving air through their filters, so this exposure is questionable at best. 


How Do You Know if Your Air Purifier is Working?

Although HEPA filtration is a trusted air purifier technology for removing air pollution, it still helps to check and see if your air purifier is working. It’s easy to forget about your air purifier, and the results can be difficult to see, but when you use the right strategies, you’ll know whether or not your air purifier is working.

One important aspect is a filter indicator. Air purifiers capture particles in their filters, and eventually these filters need to be replaced. An indicator light will let you know if you need to replace the filter, and when the light is activated you have a sign that the purifier is working properly.

You can also check the filter manually. There is a chance that the indicator light could light up prematurely (some light up based on hours used rather than your filter's remaining life), so checking the filter yourself will allow you to see that it is capturing dust, dander, pollen, and other forms of air pollution. If you see debris, dust, hair, and lint in the filter, you can see that it is working the way you expect and how much life is left in it. If your Oransi filter is dark gray and dirty then it's probably time for a replacement.

For even better proof that it is working, you can test the air before and after use. There are air-quality monitoring and testing systems that you can put to work in your home.

Some air purifiers include these air quality monitoring sensors, but from our research we've found they aren't the most reliable when included as a small piece inside the purifier. 


How to Choose the Right Air Purifier

There are many different air purifiers on the market and knowing which one is right for your needs will help you get the best results.

So, what should you look for? To decide on an air purifier, you should consider the room size, the specific pollutants you want to control, and the overall sensitivity of people in your home.

In general, the larger the room, the larger an air purifier you will need. Air purifiers can be large, small, and anywhere in between, so choosing the right one will ensure the best filtration as well as greater convenience.

The best way to know the air flow of the air purifier is to check the CADR rating. The CADR is a measure of the filtered air volume that comes out of the air cleaner. The higher the CADR number the larger the room it will clean.

In a small room, such as a college dorm room, having a small air purifier like the Finn will allow you to get the best performance without taking up too much space.

If you have a larger area, such as an office, open kitchen and living room, or an open basement, a larger purifier like the mod may be the right choice. This air purifier is rated to clean a space measuring up to 1,250 square feet with two full air changes per hour, so it can handle many spaces that other purifiers can’t.

With the right air purifier, you’ll have better air quality in your home and the ability to control dust, pollen, dander, and other airborne contaminants, but the room size and cleaning power of your air purifier needs to match up.

Even with the right HEPA based air cleaner, its effectiveness can be limited if it is not sized properly for the room or if there is too much air mixing in with the room – meaning it’s not able to keep up with the air that is circulating through the room. For example, this can occur if the unit is operating in a room with an open window. It is important to ventilate in fresh air but this needs to be managed if you are also bringing in pollutants (ie pollen and mold) that you are trying to remove.

So, do air purifiers really work to remove air pollution like particles from dust mites and pet dander?

The short answer is yes, they do remove airborne particles provided you buy a HEPA air purifier that is sized properly for your room and has sufficient air filter quality for the intended purpose.