8 Differences Between Air Purifiers vs Humidifiers (Comparison)

Here’s the outtake:

Air purifiers clean the air, humidifiers make the air wetter when it’s too dry.

There is some confusion when it comes to air purifiers vs humidifiers. Some people even wonder if an air purifier is the same thing as a humidifier. They’s are not. In fact, there are several differences between a humidifier and a purifier.

The difference between an air purifier and humidifier include:

  • How they work and function.
  • If air purifier or a humidifier help with allergies, asthma, eczema, coughing, and other health problems. 
  • Do air purifiers or air humidifiers help with dust, and clean the air in general.
  • When they are used (summer, winter).
  • How much they cost (humidifiers are really cheap, the best air purifier can be really expensive).

Example: Humidifiers increase relative humidity levels from 20% to 40%. Does that helps with allergies, or is it better to use an air purifier?

In this article, we’ll answer all of these questions. In the end, you can find an air purifier versus humidifier comparison table that summarizes all the findings.

The first thing we need to clear up, however, is the purpose of the humidifier vs the purpose of the air purifier.

In short, here is the main difference between these two devices in how they affect indoor air:

  • Air purifiers are designed to improve indoor air quality by removing air pollutants (dust, pollen, smoke, etc.).
  • Humidifiers are designed to improve indoor air quality by increasing the relative humidity levels when they are too low.

Essentially, air purifier makes the air clean, and humidifiers make air wetter. There’s a whole lot of consequences to this purpose, and we’ll jump right into them:

What Do Air Purifiers Do VS What Do Humidifiers Do?

When it comes to indoor air, we usually have two major inconveniences:

  • Air pollutants like dust, pollen, smoke, and other allergens. We want to remove those.
  • In the winter, air humidity falls to 20-30%. We want to lift it to a comfortable 40-50%.

Both an air purifier and a humidifier affect the state of indoor air. 

Air Purifier Basics

Air purifiers remove air pollutants and thereby increase the quality of the air we breathe.

These devices are comprised of two main elements:

  1. Fan that draws the polluted air in and expels the clean air.
  2. Series of filters that capture or/and destroy airborne pollutants such as dust, pollen, smoke, odors, mold, mildew, pet dander, and certain bacteria and viruses.

Here’s how the inner workings of an air purifier look (between the air purifier and humidifier, the air purifiers’ inner workings are actually more complex):

differences between inner workings of air purifier vs humidifier
Air purifier uses a fan to draw in ‘dirty air’, runs it through a series of filters, and expels clean air.

While humidifiers don’t use filters, the air purifier’s core consists of filters. These filters include HEPA filters to remove small air pollutants, an activated carbon filter to remove odors, a pre-filter to remove larger air contaminants, and so on.

true hepa filter capturing pollen, dust, mold, bacteria, smoke, dust mites
True HEPA filter is a mechanical filter that captures more than 99.97% of the smallest 0.3-micron in size air pollutants.

You can read more about how air purifiers work here or check out LM’s full Air Purifier Essentials Guide here. For specific models, you can check the best air purifier models here

Humidifier Basics

Humidifier, in comparison with an air cleaner, is a completely different device. Humidifier has nothing to do with indoor air pollution or air quality.

Humidifiers, to put it plainly, add wetness to dry air. They are usually used in winter to help us fight the feeling of dry stale air.

In the summer, we usually enjoy air with normal 40-50% relative humidity levels. In the winter, especially when the heating season starts, the humidity levels can fall below 20%.

We can feel the effects of dry winter indoor air very well. Most of us feel the most common symptoms of dry air like:

  • Waking up with a dry mouth.
  • Sneezing.
  • Eye irritation.
  • Dry skin.

According to Healthline, there are 8 main ways of how dry air can affect your health (we cover them in the next chapter).

The principle of how humidifier raises air humidity levels is fairly easy to understand. Air humidifiers create water mist in two ways:

  1. Evaporative way. Humidifier basically uses electricity to boil water and create mist; much like a tea kettle. Evaporative humidifiers create a hot mist.
  2. Ultrasonic way. Humidifiers have a transducer that creates ultrasonic waves. These waves help detect water molecules from the water surface. Ultrasonic humidifiers create a cool mist.

Here is how the basic evaporate humidifier works:

inner workings of evaporative humidifier
Humidifier is basically a tea kettle; it uses electricity to boil water and releases water vapor (or mist) into the air.

Here the deal:

An average person knows that air purifiers purify the air and air humidifiers humidify the air (it’s in the name, basically). What we really want to know when comparison humidifier vs purifiers is their effects on health.

Let’s look at how air purifier and humidifiers can help up:

How Do Humidifiers And Air Purifiers Impact Your Health?

According to the EPA, indoor air can be two to five times more polluted than outdoor air. It would only make sense that increasing the indoor air quality by using air purifiers would have an effect on our health.

On the other hand, EPA also starts their Use And Care Of Home Humidifiers factsheet with these words:

“Humidifiers are commonly used in homes to relieve the physical discomforts of dry nose, throat, lips, and skin.” (EPA)

We see that there is some indication that humidifiers too help up in several ways. We’ll look at scientific studies to get a picture of what conditions might the use of air purifier and/or humidifiers be useful for:

Does Humidifier Help With Allergies? (Comparison With Air Purifier)

In the winter, we spend more time indoors. Indoor air pollution and low humidity might affect allergies. 

Here is what Mayo Clinic says about the lack of humidifiers:

“Increased humidity may ease breathing in children and adults who have asthma or allergies, especially during a respiratory infection such as a cold.” (Mayo Clinic)

American Academy of Allergy, Asthma, and Immunology adds, “dry indoor air is often the cause of chapped lips, dry skin, and irritated sinus passages. The moisture from a humidifier can soothe dry sinus passages.”

Based on this, it seems that dry air can make allergies worse. In this sense, humidifiers can help with allergies indirectly by increasing the indoor humidity levels.

On the other hand, AAAI also warns that too high humidity levels can negatively affect allergies. Mold, mold spores, and, most problematic, dust mites grow in high humidity areas. It seems that the overuse of humidifiers can be bad for allergies.

What about air purifiers and allergies?

Indoor air contains a number of air pollutants that include known allergens, including dust particles, smoke, dust mites, mold, and especially pollen.

AHAM independently measures how effective air purifiers are at capturing pollen (pollen CADR rating). All HEPA-based air purifiers work very well when it comes to the removal of airborne indoor pollen particles.

What is more, a review of the literature by the Department of Pediatrics, University of Louisville School of Medicine titled “Effectiveness of air filters and air cleaners in allergic respiratory diseases” concludes that:

“Air filtration is frequently recommended as a component of environmental control practices for patients with allergic respiratory disease.” (Louisville study)

In short, both the EPA and available studies seems to suggest that air purifiers can help with certain allergies.

Does A Humidifier Help With Allergies More Than Air Purifier?

When comparing air purifier vs humidifiers and their relation to allergies, we can deduce that which device helps more.

Humidifiers can help us with dry air, and related discomforts of dry nose, throat, lips, and skin, according to the EPA. However, if we use humidifiers too much, we can increase indoor air humidity levels above 50%.

Too much humidity might spur the growth of mold, mold spores, and dust mites. While using a humidifier might help with allergies, too high humidity might have the opposite effect.

Air purifiers, in comparison, don’t have such opposite effects. They are designed to remove potential airborne allergens, such as dust, pollen, smoke, and even mold, mold spores, pet dander, and dust mites from indoor air.

As far as general allergens are concerned, it seems that using an air purifier is better than using a humidifier. Let’s look at asthma specifically:

Which Is Better For Asthma – Air Purifier Or Humidifier?

Many parents with asthmatic children are aware of how the quality and humidity of indoor air can influence asthma.

As we have seen from the Mayo Clinic article, the “increased humidity may ease breathing in children and adults who have asthma or allergies”. That seems to suggest that humidifiers may help with asthma.

A 2020 Korean study also suggest the same for air purifiers. Here is the conclusion of the “Effects of Indoor Air Purifiers on Children with Asthma” study:

“This study suggests that air purifiers benefit medication burden in children with asthma by reducing PM2.5 levels.” (2020 Korean study)

Essentially, studies seem to suggest a positive relationship between the use of air purifiers as well as humidifiers and asthma.

We also know that increasing indoor humidity levels too much (via the use of humidifiers) can contribute to the growth of airborne allergens, like dust mites, mold spores, and so on.

Taking this into consideration, it seems that between the two devices, air purifiers are better than humidifiers for asthma.

Air Purifier VS Humidifiers For Babies, Clean Air, Ezcema, Dust, Cough

There are a number of other effects that the general public thinks are related to either air purifiers, humidifiers, or both. Let’s look into them here:

Is Air Purifier Or Humidifier Better For Babies?

Babies breathe and are surrounded by air. Can polluted or dry air affect babies and newborns? The quality of air babies breathe, as well as air humidity levels, can play a role.

When deciding which device is better for babies – air purifier or humidifier – we are basically asking this question:

Is polluted by normally humid air better for babies than unpolluted by dry air?

It would, of course, make sense that babies should breathe and be surrounded by normally humid and clean air. 

If we have dry air, a humidifier is a good idea.

If our indoor air quality is low, an air purifier is a good idea.

It really depends on our specific situation. Regardless, however, if you both have dry air and low quality of air, it makes sense to get both a humidifier and an air purifier to fix both problems. Babies and newborns can benefit from clean air.

Does The Use Of Air Purifiers Or Humidifiers Help With Ezcema?

It’s customary to link the quality and wetness of air with skin irritation conditions. These include atopic dermatitis, xerosis, and eczema. 

It is believed that dry indoor air should have an effect on eczema, for example, and that higher humidity levels brought on by the actions of a humidifier should alleviate some problems. As of 2020, there is little scientific evidence that would suggest that. 

On the other hand, skin irritation might also be caused by indoor air pollutants. National Eczema Association suggests that you should “consider investing in house plants known for purifying the air”.

HEPA filter-based air purifiers are much better equipped to purify the air, specifically by removing the small 0.3 micron in diameter air pollutants. 

On top of that, there is some scientific evidence that connects skin conditions and indoor air pollutants. One such is the 2013 Korean study titled ‘Improvement of Atopic Dermatitis Severity after Reducing Indoor Air Pollutants‘. Korean researchers conclude that “indoor air pollution could be related to atopic dermatitis”.

In short, we have more scientific literature connecting air purifiers with eczema, atopic dermatitis, and other skin conditioners. Literature connecting humidifiers’ with eczema is virtually non-existent.

Do Humidifiers Or Air Purifiers Help Clean The Air Of Dust?

It’s a common misconception that humidifiers help clean the air. To be exact; humidifiers have no role in reducing indoor air pollutants. These devices, as opposed to air purifiers, merely humidify the air.

Air purifiers are devices that are specifically designed to clean the air by actively removing large and small dust particles, among other air pollutants.

Dust or dirty air problems cannot be solved by using a humidifier. Air purifier, however, can effectively fight dust as well as clean the air.

Do Humidifiers Help With Cough?

A cough might be a body’s response to different pollutants, air pollutants among them. Coughing can also be more likely if we’re breathing dry air.

Of course, the cause of coughing might also be unrelated to the quality or humidity of the air. In any case, indications are that humidifier might help with coughing and other symptoms of cold, according to CDC.

CDC records in their ‘Common cold’ article that one of the ways to feel better while your body fights off a cold is to ‘use a clean humidifier or cool mist vaporizer’.

Since coughing is a symptom connected with a common cold, CDC seems to be suggesting that indeed humidifiers help with coughing. 

We don’t have much information about the relation between the use of air purifiers and coughing.

When To Use An Air Purifier And When To Use A Humidifier?

Humidifiers are seasonal devices. That’s because we have dry indoor air problems in the winter. In the summer, the indoor humidity levels usually rise and we’re in need of dehumidifiers.

That’s a stark difference between humidifiers and air purifiers.

Air purifiers, in contrast, are not seasonal. They are used throughout the year because air pollutants are continually being accumulated indoors, regardless of the season.

Of course, for people with seasonal allergies, it makes sense to use an H13 HEPA filter air purifiers on higher speed settings during those seasons.

Example: Late March and April is pollen season. Trees and grasses produce pollen and it’s carried by wind inside our homes. 

Price Of Humidifiers Vs Air Purifiers

There is also a large difference between it comes to humidifiers vs air purifiers in their cost. 

Humidifiers are quite inexpensive. They usually cost less than $100, depending on the model.

Air purifiers can be much more expensive. It’s not unusual to pay more than $500 for one of the best air purifiers. Example: Molekule Air, best Dyson air purifiers, Airdog X5, Alen BreatheSmart 75i, and the best Coway air purifier cost more than $500.

Of course, there are cheaper brands of air purifiers like Hathaspace, Okaysou, Winix, and Levoit, to name a few. These can cost as little as $100.

What needs to be additionally considered when buying an air purifier is the continuous cost of replacement filters. HEPA filters and activated carbon filters need to be replaced several times per year; costs of that can easily rise above $100 per year.

Some companies do produce both air purifiers and humidifiers. This might be a potential reason why people have a harder time distinguishing between air humidifiers and purifiers; they are made by the same company.

In order to properly differentiate between air purifiers and humidifiers, we have created this summary comparison table:

Differences Between Air Purifier And Humidifier (Comparison)

As we have seen, there are a number of differences when it comes to air purifiers vs air humidifiers. You can find the summation of all the relevant differences in this comparison table:

Purifier vs Humidifier Air Purifiers Humidifiers
What Do They Do: Clean indoor air by removing air pollutants (dust, pollen, smoke, dust mites, mold, certain bacteria and viruses) Increase indoor humidity levels from 20-30% (dry air) to normal humidity (30-50%)
How Do They Work: Air filters (HEPA, activated carbon, pre-filters) remove large, small air particles, as well as adsorb undesired odors. Fan creates an airflow. Use either evaporative hot mist by using electricity to heat up water, or using ultrasonic waves to create a cool mist.
Help With Allergies: A large number of research studies seem to suggest so Some research studies seem to suggest so, may also make allergies worse
Help With Asthma: A large number of research studies seem to suggest so To a lesser degree, according to some studies
Do They Clean Air: Yes No
Seasonality: Throughout the year Winter primarily
Cost: Higher ($100-$900) Lower (Less than $200)
When Best To Use Them: When we have low indoor air quality When we have low indoor humidity levels

Based on this, you can decide which is better – and air purifier or humidifier – for your specific needs.

Can You Use An Air Purifier And Humidifier Together?

Of course. Actually, it’s advisable to use both an air purifier and humidifier if you have problems with both low indoor air quality and dry air.

That makes sense because air purifiers and humidifiers solve different problems. Both have to do with indoor air, obviously.

Is There An Air Purifier And Humidifier In One?

There are 1000s of different air purifiers and humidifiers. However, there are only a dozen or so good air purifier humidifier combos.

In short, air purifiers and humidifiers in one do exist, but they are far fewer in number than standalone purifiers and humidifiers. You can check the best air purifier humidifier combos here.

Featured Photo Credit: Alen.com

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