Last updated on June 26th, 2022

How to buy an Air Purifier tips

I remember time when I decided to get my first air purifier and how I was overwhelmed by the sheer numbers of products that at a glance offered the same functions for different price. And being in the dark about what makes an air purifier good and what I should take into consideration first I ended up getting ~$90 priced piece of badly configured plastic that didn’t do anything to improve air quality inside of my house.

Now, years later, I know how to pick air purifiers. And I’m willing to help you too by writing this quick starting guide on how to get an air purifier. Here are the main points you should consider when you are about to buy any air cleaner.

Air Purifier, Not an Ionizer!

The first thing you should know is air purifiers aren’t the same as ionizers. The first one provide a full cycle of air cleaning which is: circulating air indoor -> filtering out pollutants with filters in the process -> releasing fresh air after some time. Ionizers are only capable of preventing some viruses from floating freely all around the room, but neither kill them or capture so it is necessary to clean surfaces whether they land on (floor, walls, carpets, tabletops etc.). Plus they release ozone into air which might be harmful for some people.

So if you are looking for an air purifier, buying ionizer is the worst thing to do. Some air purifiers have an optional ionizer, but it works alongside filters so the particles are trapped inside and do not end everywhere in a room.

HEPA Filter

Absolute majority of air purifiers today use HEPA air filter (stands for high efficiency particulate air) as the ultimate method to clean air. Some HEPA-filters are considered medical-grade and used in hospitals and other health-related institutions. For obvious reason, air purifiers that employ such filters priced higher than average HEPA air cleaner.

There are some manufacturers that develop their own technology to clean air (Airdog, Molekule and some others) using filters, plates and such but it results in increased prices for us, end users. And if you see that some $50-100 air purifiers are advertised as the ultimate solution for air cleaning without saying it’s HEPA, 99% of the time it’s a hoax.

If you’re getting your first air cleaner my advice for you is the following: go with HEPA air purifier as it is a proven technology million times.

Filter Size

HEPA filters aren’t equal, they differ in sizes, quality and materials. Most of conventional air purifiers use filters produced with the same standards and similar in size; sometimes air filters for different brands produced at the same factory in China.

Obviously, bigger filter means better filtration of particulate matter (PM) from air. IQAir air purifiers employ large filters, but they are priced accordingly.

What’s is equally important is whether a filter tightly adjoins to the sides of an air purifier. It’s a common problem with filters that aren’t sold by the air purifier manufacturer but a third-party seller. An air filter must fit inside the air purifier body and do not let the air pass around it avoiding cleaning “procedure”!

Smells, Smells Everywhere!

If your main concern is odor in a kitchen, bathroom or any other smell of any kind (pet, wildfire and so on), pay attention to the existence of Activated Carbon filter in an air purifier. If an air purifier doesn’t have activated charcoal filter do not get it, even if ad says it’s 90% off.

Nowadays most charcoal filters are 2 types: impregnated and honeycomb. I recommend getting an air purifier with a honeycomb carbon filter as it simply has higher density of carbon when compared to an impregnated one.

Size of a Carbon filter matters no less than a HEPA. The bigger a filter is and higher density of carbon it has the better it filters out gases, smoke and other smells.


The most important metric you should take into account is CADR which stands for clean air delivery rate. It is measured in cubic feet per minute (CFM) and basically means how much of air a cleaner can process and deliver in a minute.

Many air purifiers (Coway, Winix, GermGuardian and others) have their metric independently tested and verified by the Association of Home Appliance Manufacturers (AHAM). So if they put in their description CADR smoke 215 you know that it’s a real number.

Why CADR rating matter? Because based on that you can calculate how many air changes per hour (ACH) a unit can achieve. Often 4.8 ACH is used as a standard, but it depends on air and health conditions. It is recommended for people with allergies and asthma to have an air purifier capable of cleaning air at least 4 times per hour.

What if you already have your eyes on a cool-looking air purifier but it doesn’t have CADR rating? In this case use our CADR calculator. But I personally has less trust in a manufacturer that hides such data from public eyes.

Don’t Fall for Sq. Ft. Numbers

You probably noticed how often manufacturers put phrases like “air purifier for large rooms” or “air purifier for 1000 sq. ft. rooms“. You should always double-check the actual room coverage with ACH calculator. Yes, an air purifier could circulate air in a 1,000 sq. ft. space in 1 hour but it twice less than the minimum of 2 air changes required for a bedroom. And many other places require way higher numbers!

So before you buy any air purifier, better to check whether the room coverage provided by a manufacturer is legit.

Size Matters

This is an obvious one, but I still mention it. Small air purifiers that consume 5-10 Watts of energy are at best capable of filtering air in a very small rooms and should be used either as car purifiers or personal purifiers that you put on a desktop close to yourself. And many of them are gimmicks, even not powerful enough to simply circulate air, let alone clean it.

Maximum Speed

After you get an air purifier turn it on and let it run at a maximum speed for a few hours. Doesn’t matter whether it has auto mode or not – just let it do it’s job for a few hours for 2 main reasons:

  • Check whether the unit runs smoothly, are there any squeaks and such.
  • Check whether air quality has improved at all.

If an air purifier passed both tests, you got a legit air cleaner. If not, return immediately.

This is all I wanted to share with you. You should also check my article on a question “Are air purifiers a waste of money?” where I address some other issues. You’re also welcomed to share your tips in the comments below!

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