Dehumidifiers vs air purifiers – what's the difference and which do you need?

Dehumidifiers and air purifiers serve the same purpose: improving our indoor air quality. But they do so in different ways. Here, we compare the two

(Image credit: Getty Images)

Dehumidifiers and air purifiers becoming common household appliances goes hand-in-hand with our growing knowledge of our air quality. Particularly for those without HVAC systems, they can improve our general health and comfort at home.

The best air purifiers and the best dehumidifiers remove pollutants, moisture and odors from our air, improving allergies, asthma symptoms and other health conditions.

But what are the differences between them? And the benefits of each? Here, we dive into what each machine is capable of and how they can change things at home.

Dehumidifiers vs air purifiers

As H&G's home tech editor, I continuously test these appliances and have written in detail about their various features, functions, and performances. I also spoke to the experts for the full lowdown on the comparisons between dehumidifiers and air purifiers.

Molekule Air Pro Air Purifier against a bedroom wall.

(Image credit: Molekule)

What's the difference?

Put simply: each appliance removes different substances from the air. Air purifiers remove particles like dust and pollen, whereas dehumidifiers remove moisture (humidity).

'They each play an integral role in maintaining proper indoor air quality,' says Peter Mann, CEO of Oransi, but they do so in different ways.

'Dehumidifiers reduce the moisture level in the air by extracting water vapor. They draw in humid air, cool it to condense the moisture, collect the water, and release the dry air back into the room,' says Asif Bux, service manager at Comfort Union.

On the other hand, Asif adds: 'Air purifiers clean the air by removing contaminants such as dust, pollen, pet dander, smoke, and volatile organic compounds (VOCs). They use filters, like HEPA and activated carbon filters, or electrostatic precipitation to trap and eliminate particles.'

Benefits of dehumidifiers

A TESLA dehumidifier in the corner of a living room.

(Image credit: TESLA)

According to sources like the EPA, the ideal humidity range at home is 30-50%. High humidity levels can encourage the growth of mold and dust mites, leading to allergy and asthma symptoms. Low humidity levels can cause dry skin, throat and nose, potentially increasing the risk of airborne viruses and eczema.

'Dehumidifiers are primarily used to control humidity levels, prevent mold growth, and improve overall air quality in damp areas,' Asif explains. 'By reducing humidity, dehumidifiers help prevent mold and mildew growth, which can cause respiratory issues and damage to property.'

Peter Mann confirms this: 'In maintaining proper humidity levels with a dehumidifier your space is less likely to have mold, as mold needs a water source for growth.'

It's also true that dust mites - the microscopic bugs that live in our homes, feed off our skin cells, and cause allergic reactions - thrive in warm, damp conditions. When we talk about dust allergies as one of the allergens in our homes, it's actually the dust mites' faecal matter.

So, as Asif puts it, 'reducing dampness can decrease dust mites and other allergens, improving health conditions like asthma and allergies.'

Aside from health, lower humidity levels can make our homes cooler and more comfortable in the summer, and dehumidifiers can be a huge help when drying clothes in the winter.

Benefits of air purifiers

We've written all about their benefits, like how air purifiers help with allergies and how air purifiers can cool down a room. But ultimately, they offer immense health benefits by filtering out many of the harmful pollutants that live in our home's air.

'An air purifier can make a significant difference in the air we breathe indoors which can have both short and long-term health benefits,' states Peter.

Mila Air Purifier surrounded by plants against a white wall.

(Image credit: Forbes)

Asif elaborates: 'Air purifiers effectively remove allergens, such as pollen, pet dander, and dust mites, from the air, providing relief for allergy sufferers. They can [also] trap harmful pollutants and VOCs, improving overall indoor air quality.'

These pollutants can include anything from tobacco and wildfire smoke to outdoor vehicle pollution, making air purifiers one of the key ways to improve air quality when living in a city.

And as we outlined in more detail in can air purifiers help with cigarette odors - they can also help to eliminate odors from smoke, pets and cooking, using activated carbon to absorb organic matter in the air.

There are some air purifiers, like the ones from Molekule, that actually destroy the organic matter within the pollutants, rather than just trapping them. They do so using PECO technology, adding a third stage of filtration that many purifiers don't use.

The question isn't about dehumidifiers or air purifiers. Both provide invaluable benefits at home in terms of health, wellbeing and comfort, and can be used alongside each other to improve your air quality at home.

But first, make sure you know how to choose the right air purifier for your home & lifestyle, and the best place to put an air purifier.

Dan Fauzi
Home Tech Editor

Dan is the Home Tech Editor for Homes & Gardens, covering all things cleaning, smart home, sound and automation across the Solved section. Having worked for Future PLC since July 2023, Dan was previously the Features Editor for Top Ten Reviews and looked after the wide variety of home and outdoor content across the site, but their writing about homes, gardens, tech and products started back in 2021 on brands like BBC Science Focus, YourHomeStyle, Homes & Antiques and Gardens Illustrated.

Dan is based in Bristol, UK with a BA in Philosophy and an MA in Magazine Journalism. Outside of work, you'll find them at gigs and art galleries, cycling somewhere scenic, or cooking up something good in the kitchen.