Humidifier vs Air Purifier: Which is Better?

humidifier and air purifier

Humidifiers and air purifiers serve different purposes and are not inherently better or worse than each other; they address distinct indoor air quality issues. Here’s a summary of their differences and how to determine which one is more suitable for your needs:


  • Purpose: Humidifiers add moisture to the air, increasing indoor humidity levels. They are primarily used to combat dry air conditions, especially in cold, dry seasons or in regions with low natural humidity.
  • Benefits: Humidifiers can alleviate dry skin, chapped lips, sinus congestion, and irritated respiratory passages. They may also help protect wood furniture and floors from drying out and reduce static electricity.
  • Considerations: Over-humidification can lead to mold and mildew growth, so it’s essential to monitor and control humidity levels. Regular cleaning and maintenance are necessary to prevent mold and bacteria buildup in the humidifier.

Air Purifiers

  • Purpose: Air purifiers are designed to remove airborne contaminants such as dust, allergens, pet dander, pollen, smoke, and pollutants. They improve indoor air quality by capturing or neutralizing these particles.
  • Benefits: Air purifiers can help reduce allergies, asthma symptoms, and respiratory irritants. They are particularly useful for those with sensitivities to airborne allergens or living in areas with poor outdoor air quality.
  • Considerations: The effectiveness of an air purifier depends on its type and filtration technology. Some units may not effectively capture certain particles, and ongoing filter replacement or maintenance is required for optimal performance.

Which Is Better?

The choice between a humidifier and an air purifier depends on your specific needs:

  • If you’re dealing with dry air, discomfort from low humidity, or issues like dry skin and congestion, a humidifier is the better choice.
  • If you’re concerned about allergies, asthma triggers, odors, smoke, or other airborne pollutants, an air purifier is more suitable for improving air quality.

In some cases, you may benefit from both devices to address different aspects of indoor air quality. It’s important to assess your indoor air quality needs, consider any existing health concerns, and choose the device that aligns with your goals for a healthier and more comfortable living environment.

Here’s a table outlining the key differences between a humidifier and an air purifier:

AspectHumidifierAir Purifier
PurposeIncreases humidity levels in the airRemoves pollutants and allergens from the air
FunctionReleases water vapor into the air to add moistureFilters and cleans the air to improve indoor air quality
Primary BenefitAlleviates dryness and helps with respiratory issuesReduces airborne contaminants and improves overall air quality
OperationAdds moisture through evaporation, ultrasonic, or steamUses filters and purification technologies to remove particles
Moisture ControlAllows control over humidity levels and outputDoes not affect or control humidity levels
Targeted ConcernsDry skin, dry throat, sinus congestionAllergens, dust, pet dander, smoke, odors, VOCs
MaintenanceRegular cleaning and occasional filter replacementRegular filter replacement and cleaning
Appropriate UseDry climates, winter months, respiratory conditionsAllergen-sensitive individuals, polluted environments

To properly understand the difference between humidifiers and air purifiers, let us first look at how they work.

How Air Purifiers Work

an air purifier

There are lots of particles in the air most of which are invisible to the naked eye. These particles can cause allergies and asthma or even bring about bad odors in the house.

The function of an air purifier is to remove these particles either by trapping them or neutralizing them. Although your HVAC system will have an air filter, the filter will only remove big particles from the air while the small and harmful ones are circulated back to the house.

For that reason, you may need to invest in an air purifier even if you have a central cooling and heating system. Air purifiers are especially helpful to folks who suffer from allergies and asthma.

It is important to understand that there are different types of air purifiers and they all don’t work the same way. The best air purifier to purchase depends on the type of particles that you want to remove from the air.

Air purifiers are designed to remove either particles or gases. There is no an air purifier that will remove both type of pollutants.

As such, there are 4 types of air purifiers based on how they work and the material they use to clean the air. They are:

  • HEPA filters
  • Carbon activated filters
  • Ionizer
  • Ultra Violet Light

HEPA stands for High Efficiency Particulate Air. HEPA filters remove at least 99.7% of particles with a size of 0.3 microns or larger. 99.7% is their worst case particle size result, meaning they perform way better than that.

What you may not know is that HEPA filters will trap smaller particles than 0.3 microns better, since 0.3 microns is considered to be the most penetrating particle size.

Air purifiers with a HEPA filter work by using a fan to pull indoor air through the filter where the particles are sieved out. Usually, these air purifiers have a cheap pre-filter (normal air filter) which filters out the big particles instead of clogging the more expensive HEPA filter.

HEPA filters will remove particles like dust, mold spores, allergens, smoke and some bacteria.

replacing air purifier filter
Replacing air purifier filter

Air purifiers which use an activated carbon filter also have a fan to pull air from the house and pass it through the filter. They however work slightly different from air purifiers with HEPA filters.

Activated carbon filters are made from a porous and specially treated medium that adsorbs pollutants and not just trap them. They remove odors and gases from chemicals, paint, smoke and volatile organic compounds.

Air filters with ionizers don’t physically remove pollutants from the air but instead they release negatively charged ions that combine with the pollutants, making them heavy and fall off from the air.

I don’t like these air purifiers very much since the pollutants fall off on the ground and furniture meaning that they can still make you ill. To remove them you would need to use a vacuum with a HEPA filter.

Because these air purifiers have the potential to recirculate pollutants back to the house, they are not nearly as effective as air purifiers with HEPA filters. You however don’t have to keep on replacing the expensive HEPA filters hence are cheap to maintain.

If you want to get rid of bacteria and viruses from your indoor air, an air purifier that uses ultra violet light is what you would need. These air purifiers uses ultra violet light to kill airborne viruses and bacteria.

While these air purifiers cannot trap particles, they are the only air purifiers that can inactivate airborne microorganisms.

I hope that by now you know how air purifiers work and which one you should go for.

How Humidifiers Work


Humidifiers are simpler machines compared to air purifiers. They work by evaporating water and then releasing the mist/fog into the air to increase the humidity in the room/house.

Most people know that high humidity is bad but low humidity is just as bad if not worse. The effects of low humidity are:

  • Dry and itchy skin
  • Respiratory infections
  • Cracked wood, furniture and artwork
  • Dry/irritated eyes
  • Static electricity
  • Dehydration
  • Nose bleeds
  • Nasal congestion
  • Worsening allergies and asthma

When humidity is too low, the air is usually quite dry. That causes the allergens in the air to lose moisture thereby becoming light and airborne. As such, these allergens are more likely to get to your lungs causing allergies.

Low humidity also dries out the nasal passage. The nasal passage is used to moisten the air as we breath in. if that doesn’t happen (because it has dried out) your body will naturally produce mucous which is what causes nasal congestion.

By increasing the humidity of the indoor air, you can prevent allergies and asthma from flaring up.

Humidifiers are mostly during winter. That is because relative humidity is lowest during the cold months of winter.

Humidity levels change with temperature. The higher the temperature the high the humidity. That is why humidity is highest during the hot months of summer.

There are warm and cool mist humidifiers. Warm mist humidifiers humidify air by boiling water and then releasing the vapor while cool mist humidifiers mechanically agitate water to create a cool mist which is then released in the house.

As you can see, humidifiers and air purifiers are very different appliances which do very different things.

Dehumidifier vs Air Purifier

A dehumidifier does the exact opposite of what a humidifier does. It removes moisture from the air when humidity is too high, usually during the hot summer months.

High humidity combined with the warmth in summer can cause mold to grow in the house. Breathing in mold can trigger allergies and asthma, and that is why you need a dehumidifier to help you maintain the ideal humidity levels in the house.

The ideal indoor humidity is between 30% and 50%. Some people can live comfortable with up to a relative humidity of 60% but if it exceeds that level you should probably get a dehumidifier.

Unlike an air purifier which traps and helps remove allergens from the air, a dehumidifier only lowers the humidity, preventing the allergens (mold and dust mites) from thriving in the house.

Another thing to note is that dehumidifiers are only used when humidity is high which is mainly in summer. However, air purifiers can be used at any time of the year since particle-presence is not greatly influenced by weather conditions.

Air Purifier vs Humidifiers on Allergies and Asthma

Air purifiers are very effective in removing allergy and asthma triggers from the air. The triggers include mold spores, dust mites, pet dander, pollen, viruses and fumes.

For an air purifier to remove the allergens from the house, they have to be airborne. Perhaps that is the main disadvantage of air purifiers. Pollutants in furniture, rags and other surfaces cannot be removed using air purifiers.

Folks with severe allergies may therefore need to also invest in vacuum cleaner with a HEPA filter. Make sure that the filter you use in your air filter or vacuum is what is called a “true HEPA filter”.

Humidifiers have no effect on the levels of pollutants/allergens in your house. What they do is humidify the air, which helps you find relief especially when you have a dried out and soar/irritated nasal passage.

Also, with the right indoor humidity, allergens like sneeze nuclei are less likely to dry out and become airborne. And as you know, if a pollutant is not airborne, it is less likely to get in your respiration system.

It is good to remember that if a humidifier is not properly cleaned, it can turn out to be a breeding ground for mold. The mold will then be released in the air and worsen allergy and asthma cases.

A humidifier should be cleaned at least twice per week using vinegar and water, 3% hydrogen peroxide solution or even chlorine bleach. Also, use distilled water to prevent mineral deposits from being released in the air.

Humidifier vs Air Purifier for a Baby

You can use either or both a humidifier and an air purifier in a nursery depending on what you want to achieve. If all you want to do is increase the air quality in the nursery, an air purifier is what you should go for.

Babies who suffer from allergies and asthma should have an air purifier in their nursery to keep the allergens at bay. Maintaining the right humidity levels is also key. If the humidity is too high, the baby can suffer from asthma attacks and in that case a dehumidifier would be needed.

If the problem you want to solve is dry air which causes the baby’s skin to dry out and become itchy, a cool mist humidifier would be ideal. Warm-mist humidifiers can burn a baby and are not recommended.

Humidifier vs Air Purifier for Sinus

If you are looking for help with sinuses, you should get a humidifier. Dry air (as a result of low humidity) causes sinuses to be inflamed.

You see, when we breath in, the nose is supposed to warm and humidify the air with moisture which evaporates from the nasal passage. When the indoor air is dry, the nasal passage dries out and hence the body results to producing mucous which causes nasal congestion.

The mucous will also obstruct the sinuses and encourage the growth of bacteria. The bacteria will cause an infection if it is left there for a long time.

A humidifier is therefore effective in preventing sinusitis because the nasal passage stays moist and the nose does not produce the excess mucous. As such, a humidifier is better for sinuses than an air purifier.

Can a Humidifier and Air Purifier Be Used Together?

Since air purifiers and humidifiers perform different functions, they can be used together in the same room. The operations of a humidifier does not affect those of an air purifier in any way.

Having said that, I would go ahead and recommend that if you are to use these 2 appliances in the same room, place them on the opposite corners of the room. Don’t have them too close to each other.

As you know, humidifier are constantly releasing water in the air. If it is placed too close to the air purifier, the filter can absorb and hold the moisture, promoting mold growth.

Air purifiers can also be placed in the same room with dehumidifiers or even portable air conditioners. Those will also not affect the air purifier in any way.

In conclusion, buy a humidifier if you want to:

  • Hydrate your skin and hair
  • Keep your eyes moist and health
  • Prevent dry and irritated throat
  • Avoid nasal congestion and sinuses inflammation
  • Maintain wood products for longer
  • Stay hydrated
  • Avoid nose bleeds
  • Do away with static electricity
  • Reduce snoring

Buy an air purifier if:

  • You suffer from allergies and asthma
  • There is lots of pet dander in your house
  • You house is bringing in dust and/or pollen from outside
  • You want to remove smoke from your house
  • There are odors in the house which you need to remove
  • You just want clean air to breath