Air Purifier, Humidifier, Dehumidifier, Diffuser: What's the Difference?

We break it down for you.


We don’t know about you but doesn’t it seem like everyone just accepted that air purifiers, humidifiers, dehumidifiers, and diffusers exist to help us improve the air we breathe and get rid of our allergies? If you've reached that certain stage in your life where you feel like you absolutely need one of those in your home (maybe it’s one of those adulting things or maybe there really is a way to breathe better air while living in the city), you must have wondered about what, exactly, makes them different from each other.

To put it briefly, air purifiers, humidifiers, dehumidifiers, and diffusers each serve a different purpose. We've got some recommendations, too, so you know what and where to buy!

What is the difference between an air purifier, humidifier, dehumidifier, and diffuser?

Here’s the short answer: Air purifiers clean the air; humidifiers add moisture to the air; dehumidifiers remove said moisture; and diffusers add fragrance to the air. Allow us to break it down for you even more.


Air Purifiers Try: Xiaomi Mijia Mi Air Purifier 2H (P6,819) PHOTO BY xiaomi

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An air purifier works to, well, purify the air. This means it cleans the air, ridding it of bacteria and other pollutants so you can breathe better. It’s the best option for those who are allergic to dust, pollen, pet dander, and more. Air purifiers usually employ filters—to purify the air, they suck the air in, filter out the pollutants, and sanitize the air before circulating it back into the room. Another type of air purifier is one that's filter-less—it cleans the air by emitting large amounts of negative ions which attach to pollutants like smoke, dust, bacteria, viruses, and mold spores. This makes the particles too heavy to stay in the air, making them drop so you won't end up inhaling them—this is how those wearable air purifiers work. You can use an air purifier along with either a humidifier or a dehumidifier (choose one—more on this later).


Humidifiers Try: Crane Digital Ultrasonic Warm & Cool Mist Humidifier (P6,999.75) PHOTO BY crane

Humidifiers are meant to be used in places with dry air—these can be air-conditioned rooms or places that are usually cold. Dry air can cause allergic reactions, which is why humidifiers are usually recommended for people who have allergies. Since its purpose is to add moisture to the air, a humidifier requires water in order to function. It turns the water into fine mist which is then released into the air to make the room more humid and less dry, reducing the chances of irritation and allergic reactions. However, since moisture is released into the air, there is a risk that mold would grow on porous surfaces like walls or window sills so it’s best to use humidifiers in rooms where air-conditioning systems are running. If you’ve got indoor plants and always have the AC on, humidifiers can help your indoor jungle thrive. To get clean yet moist air, use a humidifier with an air purifier—the air purifier will remove bacteria and other pollutants from the air while the humidifier will add moisture back into the air—win-win!


Dehumidifiers Try: KOLIN Dehumidifier (P12,950) PHOTO BY kolin

Dehumidifiers, on the other hand, remove excess moisture from the air. They’re made for places with high levels of humidity and are also known for alleviating allergic reactions by eliminating allergens like mold and mildew. Areas that are too moist or humid are prone to growing molds, which affects the air you breathe. It's best to get a dehumidifier if you want to prevent the growth of molds in certain areas of your space.


Unlike humidifiers where you’re supposed to add air into the device, dehumidifiers accumulate water since their job is to remove moisture from the air. You can put dehumidifiers in closets, shoe cabinets, and any other place that is prone to molds. When used with an air purifier, you get air that’s free of pollutants with just the right level of moisture—and because dehumidifiers remove excess moisture from the air, this makes it harder for contaminants like mold spores and bacteria to come back. Using dehumidifiers and humidifiers just cancel out each device’s purpose, so it is not recommended to use both at the same time but you can definitely have both and use each one depending on your needs and the current weather situation wherever you live.

Diffusers Try: Young Living Desert Mist Diffuser (P4,810) PHOTO BY young living


Diffusers are designed for aromatherapy and work by diffusing essential oils into the air. One can confuse diffusers with humidifiers since both add moisture to the air, but a diffuser’s primary function is to make the air smell better with scents that depend on your essential oil of choice—humidifying the air is a side-effect. If the latter is your goal, a diffuser may not give you the results that a humidifier would unless specifically designed to do both. Diffusing essential oils into the room is known to relax and rejuvenate the mind and body—but that’s a whole new topic that deserves its own article.

This story originally appeared on

* Minor edits have been made by the editors.

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