What is the Difference Between Air Purifier and Humidifier? Explained in Detail

Today’s average American home needs so many appliances. Thus, you might be trying to find out what can serve two purposes. That’s why you might want to know more about humidifiers vs. air purifiers.

Unfortunately, here, you will see that one cannot be used in place of the other.

Some people ask whether they can buy an air purifier and forego the humidifier. Well, it depends on a few things.

If you live in an area that has dry air in winter or throughout the year, you will need a humidifier.

It breaks down water into tiny droplets that it releases as mist into your room. This mist can be warm or cool.

But for pure air, you will need something else—an air purifier.

An air purifier purifies the air. A humidifier raises the humidity inside the home, but it does not purify the air.

Thus, instead of asking whether you can just buy the best air purifier for your indoor air and forego the humidifier, you can just buy both of them.

Or you can get a two-in-one air purifier and humidifier. It can remove pollutants from the air and increase the humidity level at the same time.

You could even run the air purifier and your humidifier for a large room at the same time. That way, you enjoy clean air with the right humidity.

Similarities between the two

Similarities between humidifier vs air purifier

If you are reading this and you are thinking there must be a reason why we have grouped these two appliances.

Well, similar to our post on humidifiers and diffusers, it is because they have some similarities.

Both of them enhance the quality of the air that you enjoy indoors. They can make your indoor living spaces quite comfortable.

If you have ever experienced sleeping in dry air consistently over several days or weeks, you know how uncomfortable it can be.

That is why you need the best cool mist or warm mist humidifier to raise the humidity in the air to the required levels.

After all, the air feels quite mellow when it has enough moisture in it. It is friendlier to your nasal membranes. It is also better for your airways, your throat, and your lungs.

In addition, well-humidified air is also good for people who suffer from asthma. Let’s just say a humidifier will make the air more breathable for people with respiratory illnesses. It even helps with allergies.

The air purifier, on the other hand, is also good for people with asthma. It also enhances the air quality so that it is better and healthier for the airways.

An air purifier is very helpful for areas that have contaminated air. It can remove all bacteria, thus giving your family clean and fresh air all the time.

If you experience breathing difficulties, an air purifier should help make your life better, and so should the humidifier.

So we agree that both appliances are important for your home in this manner:

  • The humidifier is for areas with dry air
  • The air purifier for areas with contaminated air

Differences between the two appliances

Differences between humidifier vs air purifier

Enhancing the quality of your indoor air is just about where the similarities between these two appliances end.

And the differences begin!

A humidifier uses water and adds mist into the air

Both may not look so different, but the internal mechanism is totally different. For example, a humidifier uses water, so you have to fill its tank with water. It won’t produce mist without water.

Whether you get an ultrasonic humidifier, a cool mist, a warm mist, or an evaporative humidifier, the concept is about the same. They all use water. Thus, when the tank runs dry, it stops working.

Usually, indoor humidity should be between 30 and 50%. Thus, when you have set whatever level of humidity you need, the humidifier stops when it has reached that.

When looking for the best humidifier, make sure it has automated features. Such include a built-in humidistat, which shuts it down once the right level of humidity has been attained.

Please note: Only the bigger portable humidifiers and furnace humidifiers have built-in humidistat.

Some people also ask what is best in a humidifier vs. an air purifier for a baby’s room. Well, both are great for the baby.

One ensures that the air the baby is inhaling is free of contaminants. The other ensures the air has the required humidity.

An air purifier removes odor and contaminants from the air

Air purifier removes odor and contaminants from the air

A humidifier adds moisture to the air that you breathe. However, an air purifier does not add anything to the air.

The air purifier sucks the air in your room into its filters. The filters then remove odor and contaminants.

They release clean, fresh, and odor-free air into the room. When you inhale this air, you will feel the difference.

It’s possible to have good humidity in the bedroom or any room, yet at the same time, the air will be contaminated with allergens, bacteria, and odor. This is where an air purifier comes in.

The air inside the house can contain minute contaminants, but an air purifier will get rid of them. A humidifier cannot do this.

Since the humidifier and air purifier do different jobs to the same air, you can run both of them side by side. This way, you will enjoy optimum humidity as well as pure and healthy air.

The operation of an air purifier does not interfere with the operation of the humidifier. They complement one another rather well.

A humidifier does not pull air into itself. It adds mist in the air. This mist is formed from the water in the tank.

An air purifier on the other hand uses fans to suck air into itself, and then it traps all contaminants in the air in its filter. These include bacteria, pollen, pet dander, dust, chemicals (VOC), smoke, and odors.

Types of humidifiers

In this section, you will find more differences between humidifiers and air purifiers. One of them is that humidifiers come in many types.

Image of cool mist humidifier vs air purifier

See below:

1. Ultrasonic humidifiers

These are by far the most popular humidifiers. They use ultrasonic vibrations to produce the tiniest droplets that are then blown into the rooms by small and quiet fans as mist.

These humidifiers have a diaphragm that vibrates at high frequency, hence the name ultrasonic. The vibrations turn mist into water.

Humidifiers require good care and maintenance. Otherwise, they could fail to work properly.

2. Warm mist humidifiers

These may not be as popular as the cool mist humidifiers but they are still very good. The main reason why people do not like them is that they pose a scalding hazard if used in a room with kids.

Apart from that, they are very good for releasing warm mist into the room.

The best thing about warm mist humidifiers is that they boil water and in the process, they kill bacteria, fungi, and viruses in the water.

To some extent, they cleanse the air. However, if you use one with hard water, it is going to form mineral deposits on the tank, so you will have to clean it more often.

Check the heating elements carefully because when scale builds up on them, the humidifier fails to steam.

3. Cool mist humidifiers

They work on the same principle as warm mist humidifiers. However, instead of releasing warm mist into the room, they release cool mist.

They don’t have heating elements, so they do not boil water. Also, ultrasonic humidifiers are cool mist ones. They leave white dust if you use water with minerals.

They do not kill germs in the water. However, since they have filters, they will get some of the impurities out but not with the efficiency of the air purifiers.

If you are looking to increase humidity in the room of your baby, a cool mist one is better than a warm mist one.

4. Evaporative humidifiers

Evaporative humidifiers differ slightly in design from the warm or cool mist ones. They have a wick that is in direct contact with the tank.

When the wick gets wet, a fan then blows over the wick, in the process dispersing mist to the room.

Evaporative humidifiers also have a filter that traps germs, bacteria, and other impurities so that they are not introduced into the room with the mist.

Please note that even if many humidifiers use filters that trap impurities and bacteria, they can’t come any close to how effectively an air purifier works.

The reason for this is that an air purifier sucks in the contaminated air from the room, cleanses it, and then releases it back into the room.

Air purifier for allergies

Image of air purifier for home

Air purifiers are the undisputed champions when it comes to getting rid of the notorious indoor allergens in your home.

Humidifiers do this too, but they only do it on a small scale. For example, they help with plant pollen in spring.

By adding some moisture to your indoor air, the pollen becomes damp and heavy, falling to the ground as a result. Thus, a humidifier can help a lot in spring.

However, also note that a humidifier may on the flip side help in the proliferation of indoor allergens such as mold and dust mites. If you do not keep the humidity well controlled, it may help these allergens to spread.

Thus, even as you run your humidifier to increase your in-house humidity, you also need to find a way of removing the allergens. That is why we said you can run a humidifier alongside an air purifier.

Types of air purifiers

Usually, the type of air purifiers depends on how they purify the air. There are two types of air purifiers – active air purifiers and passive air purifiers.

1. Active air purifiers

These ones are not very common in the market today. However, for the right of mention, they release negatively charged ions into the air.

These ions make the air pollutants stick to surfaces. You can see the reason why these types of purifiers are not very popular.

2. Passive air purifiers

These are the most common types of air purifiers in the market. They suck the air from the room and pass it through filters that capture chemicals, germs, fungi, viruses, mold spores, other allergens, and odors from the air. The purifier has a fan that whips the clean air back into the room.

Today, passive air purifiers use HEPA (High-Efficiency Particulate Arrestance) filters. These filters are designed and installed in the appliance in such a way that no air escapes filtration.

Sometimes, another filter may precede the HEPA one, especially in air purifiers made for use in dusty areas.

HEPA filters can remove 99.9 percent of impurities most common in the air.

Humidifier vs air purifier for asthma

Humidifier vs air purifier for asthma

In the debate for humidifier vs air purifier, you will find that the latter always wins if allergens are concerned. If you have an asthmatic person living with you, it is recommended to get an air purifier.

And why are we concerned with allergens so much while this section is about asthma? Simple; allergens trigger asthmatic attacks. These include dust, smoke, pet dander, dust mites, mold spores, and many more.

To make life much easier for a person suffering from asthma, a chronic condition, you will need to know all the triggers and eliminate them. In this case, a purifier would be handier than a humidifier, but even the latter can help.

Specifically, look for an air purifier designed to reduce allergens in the air. There are many such appliances on the online marketplaces.

Allergens such as pollen, dust, dust mites, pet dander, and mold spores are some of the biggest triggers of asthmatic attacks. This is why you should strive to get rid of them all the time.

Since these allergens float in the air where they are inhaled, it is best to eradicate them as soon as possible, using a purifier.

Does a humidifier help with asthma?

Is there any other way in which humidifiers may help with allergies and asthma? There is. One of them is that they make the air softer for the airways, and we know that asthma and other respiratory illnesses make it hard to breathe.

While a humidifier will only ease the symptoms of an allergic attack, it is better than nothing at all. However, the best air purifiers are the real deal when it comes to taking care of indoor allergens.

People who have asthma will certainly breathe easily and more comfortably when the in-house air is at optimum humidity.

It is recommended that you keep it at between 40 and 50% all the time. Any higher and too much dampness in the air can trigger an asthmatic attack. Life is a balancing act!

As you have seen here, if you have dry air in winter, or you just live in a place that experiences dry air almost all of the year, buy a humidifier.

If you live in an area that is close to industries that are always releasing smoke into the atmosphere, you need an air purifier. Such smoke will no doubt have chemicals.

If you have a baby, buy a humidifier and an air purifier. A baby’s lungs and airways are more sensitive than a grown-up’s. They are more sensitive to dry air, or air with chemicals, gases, smoke, dust, and other impurities.


The humidifier vs air purifier comparison is not a win-win or win-lose situation. It is a matter of finding out what you need and buying it.

Chances are that if you find that you need a humidifier, you will buy even the air purifier because a humidifier may encourage the growth of mold and dust mites.

In that case, you would need a good air purifier to get rid of these allergens.