Air purifiers vs dehumidifiers - which is best for your needs?

Both can make the air in your home cleaner, but which should you choose?

air purifier illustration
(Image credit: Getty images)

No matter how frequently and how thoroughly we clean our homes, microscopic dust particles, pollen and other allergens, smoke, moisture and mould will always be present. While this is normal, it can make our lives uncomfortable at times, especially for those who suffer from allergies or respiratory issues.

The good news is we can make the problem much better by investing in the best air purifier (opens in new tab) or dehumidifier. But how do you know which is right for your needs? Here, we’ll look at: what each product does, what they’re best for and the pros and cons of both, so you can choose the one that’s right for you.

What do air purifiers and dehumidifiers do?

Air purifiers and dehumidifiers are similar in that they remove the nasties that swirl around the air in our homes, but how they do it differs, so the two are not interchangeable.

Air purifiers

Air purifiers work by using high-efficiency particulate arresting (HEPA) filters to trap dust particles and other pollutants. A fan draws air from the room and passes it through a series of filters, before recirculating the cleaned air back into the room.

Some models also include an ionising function, which uses electricity to charge the ions in the air and capture even more particles. While this is good for particularly sensitive allergies and respiratory problems, this function produces ozone, which can be harmful to our health, whereas those that use only HEPA filters don’t, so do think about that when buying one.


Where air purifiers clean airborne contaminants from your home, dehumidifiers draw moisture from the air and deposit those minute water droplets – and the mould and microbes they contain – into a container, which is then manually poured away. Dehumidifiers do not clean the air and recirculate it as air purifiers do.

As well as removing germs and mould, dehumidifiers (as the name suggests) lower humidity levels. Ideally, the moisture levels in your home should be less than 50%, but if it’s not properly insulated or you have small gaps around windows and doors, chances are excess moisture will creep in and form condensation.

Who would benefit from having an air purifier or dehumidifier?

  • If you have allergies to pet hair, pollen or other contaminants, are a smoker or live with a smoker, or live in a busy household with lots of children (more activity creates more dust) or an old house that produces excessive amounts of dust, then anair purifieris for you.
  • Dehumidifiers are best for people who suffer from breathing issues or have problems with mould and mildew in their homes or excessive condensation. If your bathroom doesn’t have a fan to remove condensation after bathing and showering, a dehumidifier is a great way to stem the tide of mould and mildew build-up.

Air purifier or dehumidifier - pros and cons

Let’s start with air purifiers.

  • Aside from the benefits that we’ve touched upon already – removing allergens, dust, smoke and other pollutants – they can get rid of odours, too, which is especially beneficial if you have pets. No matter how often we bathe them, clean out their cages and vacuum up after them, pets can start to smell a little from time to time. So, rather than wash your pooch every other day, let an air purifier do the work and remove odours before they build up (though please do wash your dog regularly – they still need a good bath once in a while!).
  • If you live near a busy main road or in a city, exhaust fumes, dirt and pollution will work their way into your home and an air purifier can help combat this.
  • One of the drawbacks of air purifiers is that they can be noisy, so always check the decibel levels before buying. Some require you to buy new filters, so factor that into the overall cost of one. They can be big and bulky, especially if you’re purifying a large room, and although they’re getting more aesthetically pleasing all the time, most air purifiers don’t win many prizes for their looks.


  • We’ve touched upon the fact that dehumidifiers can reduce condensation, mould and mildew, and help breathing-related problems, but they can also help control pests that thrive in damp conditions, such as spiders. Consider one, too, if you have a damp problem in your home. A dehumidifier won’t eliminate it, but it can stem the flow and stop things like peeling wallpaper and flaking paint caused by excess moisture.
  • Like air purifiers, dehumidifiers aren’t the best-looking of appliances and can take up quite a lot of space, too. They can be noisy, so keep an eye on the decibel levels of the models you like, and, of course, you have to remember to empty the water container regularly.

Writer and broadcaster Carrie Marshall has been writing about all kinds of technology since 1998. Carrie’s CV is a who’s who of magazines, newspapers, websites and radio programs ranging from T3, Woman & Home, Techradar and MacFormat to the BBC, Sunday Post and People’s Friend, and she offers straight-talking tech advice on BBC Radio Scotland every Monday. Carrie has also written thirteen non-fiction books and ghost-written two more, and she has also been the co-writer of seven books and a Radio 2 documentary series. Her memoir, Carrie Kills A Man, will be published in late 2022.