If you’re trying to improve indoor air quality in your home, you’ve probably come across a wide variety of products—from air purifiers and dehumidifiers to humidifiers—all claiming to help. With so many contaminants and conditions to consider (like humidity levels, mold, and pet dander), knowing what works for your specific concerns is key.

Below, we break down the difference between an air purifier and a dehumidifier, when to use each, and whether you can (or should) use them together. If you’re wondering “can you use a dehumidifier and air purifier at the same time?” or “do I need a dehumidifier or an air purifier for allergies?” – you’re in the right place.

What is the Difference Between an Air Purifier vs Dehumidifier?

Air purifiers clean the air by removing pollutants. Air passes through the purifier’s various filters that hold or remove pollutants so that only clean air is emitted back into the room. Depending on the technology of the product, some air purifiers can have better performing filtration systems. An air purifier’s purpose is to “clean” the air; it does not and cannot change household humidity levels.

A dehumidifier, on the other hand, doesn’t purify the air. Instead, it removes excess moisture from the air to reduce high humidity levels—an ideal condition for mold, dust mites, and mildew to grow. This makes a dehumidifier especially important for mold prevention and for homes in humid climates or with musty odors.

Humidifiers serve the opposite purpose of dehumidifiers. They introduce moisture into air that feels “too dry” in certain seasons.

How Do I Know if I Need an Air Purifier vs Dehumidifier?

Since air purifiers and dehumidifiers perform different tasks for your home, there’s nothing wrong with having both. But if you notice any of the following symptoms in your home, it is definitely time to invest in a dehumidifier:

• Windows show condensation on the inside, especially in the mornings
• Rooms feel stuffy, the air feels heavy
• You smell mustiness or mold when you enter a room or area
• You can see moist or damp stains on walls, ceilings, or other surfaces

Is High Humidity Bad?

High humidity is bad for many reasons; it can impact everything from your health to your home. A dehumidifier will work to prevent or remediate most of these problems by removing extra moisture from the air. Here are some situations where a dehumidifier can help lower high humidity and improve air quality:

• Mold remediation and prevention – mold thrives in conditions over 60% RH, so if you’re noticing a musty smell, mold growth, or if your symptoms are related to your health, consider checking your humidity levels or even calling in the experts to check for mold. A dehumidifier will help lower humidity levels to prevent mold from growing.
• Dust mites – since dust mites enjoy humidity, creating a hostile environment for these invisible allergens can lower their levels and ease allergy-related symptoms. They cannot survive below 50% RH.
• Asthma – because asthma attacks can be triggered by air pollutants, a dehumidifier will ensure your humidity levels are kept low enough to minimize the growth of bacteria, dust mites, and mold.
• Structure and furniture – overly high humidity levels can affect the structural integrity of your home. Wood can rot from excessive moisture while metalwork can begin to rust. Even furniture can gather bacteria and dust mites or start to smell musty. High humidity can also create unseen problems, like the ones hiding in the ductwork of your home.

There are some situations where you may need to increase humidity levels, supporting that a humidifier can be used in some situations to improve air quality. Here’s where a humidifier vs dehumidifier is actually a better solution:

• Newborns – if you have a baby, then a humidifier can make a good addition to a nursery. Humidifiers can increase moisture in dry air that would otherwise exacerbate scratchy throats and noses, especially during the drier winter months.
• Illness – According to researchers from the NIH, National Institutes of Health, humidity levels can limit the spread of Covid-19 and other airborne viruses. Increased humidity can also make symptoms of some illnesses feel less severe. Be cautious, though, of increasing humidity too much, or for too long.

Can I use an Air Purifier and Dehumidifier Together?

Yes, you can absolutely run a dehumidifier and air purifier at the same time. Many people search “can you use air purifier and dehumidifier in the same room?” and the answer is yes—with one note: keep them a few feet apart. Don’t place your humidifier or dehumidifier too close to the air purifier, as excess moisture could affect the purifier’s filters.

If you're using a dehumidifier air purifier combo or a 2-in-1 air purifier and dehumidifier, be sure to check that both functions operate efficiently. These combination units are ideal for small apartments or basements, but separate devices may offer better performance for larger spaces.

What to Do?

Now that you’re more familiar with the differences between an air purifier and dehumidifier, you can begin to assess you home and goals to determine which is best for your situation. Keep in mind that an air purifier can be used year-round while a dehumidifier or humidifier is typically only used for shorter periods of time. Dehumidifiers are often used during the spring and fall seasons, when it is cool but humid outdoors; they might also be switched on during especially humid summer months. And, of course, both can run while an air purifier works to address air pollutants.

If you’re still wondering whether you need a humidifier, dehumidifier, or air purifier, think about what symptoms or air issues you’re experiencing and check your indoor humidity levels.

Learn more about how air filters, air purifiers, and air scrubbers work in different ways to improve indoor air quality.

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