Dehumidifier Vs Air Purifier – What’s The Difference?

The main difference between an air purifier vs dehumidifier is that a purifier uses a filter to capture and reduce pathogens, while a dehumidifiear reduces moisture to decrease pathogen activity. 

You can use both devices to provide cleaner air for your home. If you suffer from allergies, especially to mold, either one can be helpful. But the way dehumidifiers and purifiers work are very different, and each is optimized to tackle different problems.

dehumidifier vs air purifier

What Is the Difference Between Air Purifier and Dehumidifier?

Both dehumidifiers and purifiers have the potential to reduce the number of allergens in your air. But each operates in a different way to get this done. And equally important, each has different uses beyond reducing allergens that should also be taken into consideration.

PurifierDehumidifier
How It WorksUses filters to capture and neutralize particles and odors.Uses condensation to remove moisture from the air.
Effects on AllergensReduces allergens like mold, dust, pollen, and dust mites in the air by filtering them out.Reduces allergens like mold and dust mites by reducing humidity and making the environment less optimal for growth.
Additional ApplicationsCan also capture viruses, bacteria, pet hair, smoke, and other impurities in the air.Can reduce humidity to make the home feel more comfortable. Useful for cleaning up after a leak or flood.
Optimal UseTo purify the air in the home of allergens, VOCs, smoke, and/or pathogens.To reduce humidity levels in the home to reduce mold growth, dust mite activity, and increase comfort.

Dehumidifiers

EnergyRated hOmeLabs dehumidifier on the floor

Dehumidifiers use refrigerants or desiccants to pull moisture from the air. By turning that moisture into liquid water, they decrease humidity levels.

These appliances are especially useful in areas that experience high humidity during the summer. By reducing moisture levels in the air, they can make hot temperatures feel much more bearable.

A dehumidifier can also provide relief for those sensitive to mold spores, mildew, and dust mites. This is because lower moisture means mold is less likely to grow on surfaces of the home. Dust mites are also known to thrive in humid conditions. In homes kept under 50% humidity, dust mite activity is lower than in homes with higher moisture levels.

From small countertop models, bedroom dehumidifiers to whole house units, dehumidifiers come in various sizes. Deciding what dehumidifier size is best for your needs depends on the total dimensions of the room and the amount of moisture you are contending with. 

Types of Dehumidifiers

picture showing the difference between desiccant and refrigerant dehumidifier

There are two main types of dehumidifiers. Each uses a different method for pulling moisture from the air, but the outcome is the same.

  • Refrigeration Dehumidifier – These dehumidifiers use coolant chemicals to cool a grid of pipes. Air is drawn into the unit and over these pipes using a fan. When moisture in the air touches the cold pipes, it condenses into liquid water. This water runs down the pipes and collects in a reservoir or drains out through a hose.
  • Desiccant Dehumidifier – These units use desiccant material to soak up moisture from the air. This material is usually attached to a large motorized wheel that spins to pull air into it. The continuous spinning motion pushes the liquid water to the edge of the fan, where it drips into a reservoir or out a drainage hose.

For a more complete look at how these two dehumidifier types differ, check out our article How Does a Dehumidifier Work.

Air Purifiers

Okaysou Air Purifier on the kitchen countertop

Air purifiers use a fan to pull air through a filter or set of filters. Some units may also include electronic features such as UV lights and ionizers to further neutralize irritants and odors.

The type of filter used in these devices varies greatly from one device to the next. But most do a decent job trapping large particles like hair and dust. A quality air purifier can also trap tiny particles such as smoke, pathogens, and allergens.

Air purifiers do not change humidity levels, nor do they cause changes to the environment to restrict mold or dust mite growth. They can, however, restrict the movement of these particles by filtering them out of the air, thereby reducing the possible spread of mold infestations to other parts of the house. 

Types of Air Purifiers

a person holding an air purifier filter

Although the shape and size of air purifiers differ greatly between models, the unit’s filter type determines what situation each model is optimized for. Here are the most common filter mechanisms found in household air purifiers.

Filter TypeHighly Effective Against
True HEPADust, hair, dander, pollen, mold, pathogens, smoke particulate
HEPA-likeDust, hair, dander, some pollen, some mold
CarbonOdors, VOCs
IonizerAtmospheric dust, small smoke particles, viruses, bacteria, mold spores
UV LightViruses, bacteria, mold
  • True HEPA Filter – True high-efficiency particulate air filters are the gold standard of air purification. These filters trap at least 99.97% of particles with a size of 0.3 microns. Smaller and larger particles are generally captured at an even higher efficiency. H13 and H14 rated HEPA filters are especially effective at capturing tiny particles around 0.1 microns in diameter.
  • HEPA-Like/HEPA type Filter – Filters referred to as “HEPA-like” or “HEPA type” are dense like a True HEPA filter but have failed the performance test to receive the official HEAP rating. How effective these filters vary greatly. The only sure thing is that they are not capable of filtering 0.3-micron particles at a rate greater than 99.96%.
  • Carbon Filter – HEPA filters act on particles and have zero ability to trap or neutralize gaseous odors. Carbon filters, which are made of highly absorbent activated carbon, can absorb these gaseous substrates. These filters are effective against odors and volatile organic compounds (VOCs), which are known to be hazardous to human health.
  • Ionizing Filter – This filtration technique releases ions into the air that attach to small particles. The addition of an ion creates an electrical charge that causes these particles to get trapped more effectively within the air filter. Charged particles that aren’t trapped are more likely to stick to the surfaces of your home and less likely to float around in the air. This filtration technique is advantageous for tiny particles smaller than 0.01 microns, like atmospheric dust and certain types of smoke.
  • UV Light Filter – Ultraviolet light is harmful to living cells. Some purifiers feature internal UV lights that act against pathogens as they flow through the system or after they get caught in the filter. These purple lights break apart viruses, bacteria, and mold and are especially effective in the fight against mold infestations and contagious illnesses.

Info: The type of filter used in an air purifier determines how effective the appliance is against various airborne irritants. When shopping for a new purifier, you should also consider the airflow rate (CFM) and efficiency rating (CADR) to understand if the unit is the right size and strength to purify the area of your house where you intend to use it.

Some air purifiers, like the iAdaptAir from AirOasis, have many performance features like WiFi connectivity, auto-mode, and more in addition to multiple effective filters.

Should I Buy a Dehumidifier or Air Purifier?

EHG writer Sara sitting next to a dehumidifier

Whether you should buy a dehumidifier or an air purifier depends on the specific challenges you’re facing. While there is some overlap in what they can do in a broad sense, they are each tailored to specific uses.

The below table illustrates which issues each device is effective for.

IssueDehumidifierAir Purifier
Mold Growth
Mold Spread
High Humidity
Dust 
Dust Mites
Smoke
Viruses
Bacteria Spread
Bacteria Growth
Pollen
Musty Odor
Offensive Odors
VOCs

Note: How effective an air purifier is against different airborne particles and odors depends on what filter type it is equipped with.

Considering the benefits of dehumidifiers and air purifiers can also help you decide which will best meet your needs.

Benefits of a Dehumidifier

  • Reduces humidity.
  • Neutralizes musty odors.
  • Reduces dust mite activity.
  • Reduces mold growth.
  • Helps prevent mold growth after a leak/flood.
  • Helps prevent mold and mildew growth in bathrooms.

Benefits of an Air Purifier

  • Removes allergens from the air to reduce allergy symptoms.
  • Helps purify the air to reduce symptoms associated with respiratory disease.
  • Helps slow the spread of contagious illness.
  • Neutralizes and kills mold, bacteria, and viruses.
  • Neutralizes smoke particles from cigarettes and wildfires.
  • Neutralizes odors from pets, smoke, and cooking.
  • Reduces the spread of mold.

Air Dehumidifiers vs Air Purifiers for Allergies and Asthma

If your allergies and asthma are aggravated by pollen, pet dander, and dust, then an air purifier is your best bet for reducing symptoms (although dehumidifiers do help too). A quality air purifier with a HEPA filter will trap most of these allergens to keep your home air cleaner. On the other hand, a dehumidifier will only reduce mold and dust mite numbers.

Dehumidifier vs Air Purifier for Mold

Dehumidifiers reduce the humidity in the home to prevent mold growth on walls, in basements and bathrooms, and in other areas where the unit is used. Less active mold growth equates to fewer mold spores being released into the air. By reducing humidity, dehumidifiers retard mold growth and mold spread throughout the home.

Air purifiers capture mold spores to reduce mold spread. But, because they do not affect humidity levels in the home, they do nothing to minimize mold growth in the first place.

If you have trouble with mold growth in your home, using both appliances at once might be your best approach to stopping the growth and reducing the spread. 

If you have questions about where to place your dehumidifier to optimize its effectiveness, check out our article on How to Use a Dehumidifier.

Dehumidifier and Air Purifier FAQ

Does a dehumidifier clean the air?

A dehumidifier doesn’t clean the air or capture particles and impurities the way an air purifier does. Rather, a dehumidifier pulls moisture from the air to reduce humidity. This, in turn, creates a less optimal environment for mold and dust mites, which reduces mold growth and spread and dust mite activity.

A dehumidifier does not affect the number of other impurities in the air. If you’re interested in purifying your home against bacteria, viruses, and other pathogens, you need a quality air purifier equipped with a UV filter.

Can you use a dehumidifier and air purifier in the same room?

Yes, you can use a dehumidifier and air purifier in the same room. In fact, this is one of the best ways to tackle an active mold growth problem.

If you’re dealing with excess humidity after a flood or leak, it is best to run the dehumidifier alone at first. Once the humidity levels have fallen to a more normal range, you can then start the purifier. This will prevent the carbon filter in the purifier from being damaged by excess moisture in the air.

Are air purifiers a waste of money?

A quality air purifier is not a waste of money. It can effectively remove allergens from the air, reduce the spread of airborne disease, remove harmful VOCs, and neutralize smoke particles and odors.

Air purifiers do require some upkeep in the form of replacement filters, but this cost is worth it for better air quality.

Dehumidifier vs Air Purifier: Both Have Their Place In the Home

Both dehumidifiers and air purifiers can be effective against mold and dust mite activity in the home, but how they accomplish this and what other benefits they provide differ significantly.

Dehumidifiers are great for decreasing humidity levels to make your home feel more comfortable and reduce mold growth. If you live in a humid climate, have a damp basement, or recently experienced a leak or flood, a dehumidifier can make a huge difference in your fight against humidity, odors, and mold.

Air purifiers are effective against a wide range of airborne impurities, including mold, pathogens, dust, dander, pollen, and smoke. If you struggle with respiratory problems, allergies, asthma, or immune problems, an air purifier is a must.

Still have questions about the differences between air purifiers and dehumidifiers or when to use each? Be sure to post them in the comments section below.

About The Author

Aaron is the founder of and Essential Home and Garden. He likes to spend his spare time with his family, and doing DIY projects in the home and garden.

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