What Is a Humidifier Used For? The Benefits and the Risks Explained

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A humidifier can be a relatively inexpensive home appliance but one that can be incredibly useful.

In fact, when it comes to the question, “what is a humidifier used for?” the answer is a lot more extensive than you probably thought.

Humidifiers are great to have on hand if someone falls ill, but these practical machines can also help prevent illnesses. They’re also incredibly helpful if you live in an arid climate, experience dry winters, if you have problems with snoring, or if you just want to have happier houseplants.

But even more important to understand than how a humidifier is used is how to use one safely. We’ll tell you everything you need to know about that and about the five different types of humidifiers in this article.

an ultrasonic humidifier releasing a cool, fine mist in the living room

When Should You Use a Humidifier?

Humidifiers, as the name suggests, are used to add moisture to the air. What people don’t realize is how and when such a thing can be useful.

Powering up your humidifier when the air is dry can make a huge difference in how comfortable you feel inside your home. But this little unit can also help during times of illness or potential illness, to reduce snoring, and improve the health of your houseplants.

In Dry Climates

The most obvious use for a humidifier is to add moisture to the air when you live in a dry climate.

The optimal humidity levels inside the home are between 40% and 50%. If your air is drier than this, then you may experience symptoms including:

  • Dry skin
  • Cracked lips
  • Dry or bloody nose
  • Dry throat or dry cough
  • Sinus congestion 
  • Headache

By using a humidifier in your home or even just in your bedroom while you sleep, you can greatly decrease the severity of these symptoms and help your body find some relief from arid air.

During Winter

Even in non-arid climates, the air inside your home can dry out during the winter.

Heaters, fireplaces, and other devices used to keep you comfortable during those frigid months can do a number on the moisture level in your home. Dried-out air may be to blame if you experience any of the above symptoms during the winter.

By using a humidifier or adding a whole-house humidifier to your HVAC system, you can easily counteract the drying effects of your heater.

When You’re Sick

a person using a humidifier during winter

Respiratory viruses cause inflammation and irritation in the sinuses, throat, and lungs. These symptoms can be compounded when the air in your home is drier than it should be. Even if you don’t have low humidity, the mucus membranes in your mouth and throat can quickly become drier than normal when a stuffy nose forces you to breathe through your mouth.

Using a humidifier, especially while you sleep, can help reduce these symptoms.

Humidifiers can also help make a dry, unproductive cough more productive by adding moisture to your lungs and airway. According to the Mayo Clinic, this can be especially helpful in sick adults and children who also suffer from asthma.

During Flu Season

Don’t wait to kick on your humidifier until after you’ve already fallen ill, though. Because these useful appliances can actually help prevent the spread of illness. 

Viruses like those that cause the common cold and the flu must be introduced into a person’s respiratory system either through being breathed in or by surface area contact with a mucus membrane. Most of these illnesses are spread by virus particulates being released into the air after a sick person coughs or sneezes.

Research into the spread of influenza viruses via air transmission has shown that these particles are most infectious at low relative humidity—under 20%. At higher humidity levels, the particulates are quickly deactivated, with the greatest drop in activation starting at around 45% relative humidity.

Running a humidifier in your home during flu season or when a family member is ill, can greatly reduce the chances that your whole family will get sick.

To Reduce Snoring

Dry air causes the mucus membranes of the sinuses and throat to dry out. When these cell layers are dry, they lose elasticity and lubrication, causing the cells to become irritated.

This irritation can quickly lead to inflammation of the airways. While this isn’t likely to cause any emergent breathing problems, it will cause snoring to worsen in those prone to the condition.

By using a dehumidifier at night, you can help keep these respiratory surfaces lubricated and prevent the inflammation that causes snoring.

For Healthier Houseplants

a person adjusting the mist level of a humidifier

The respiratory system of humans isn’t the only thing that prefers moist air. Many houseplants are tropical varieties that have evolved in humid climates. So, it makes sense that these plants would thrive in homes with higher relative humidity.

Most houseplants prefer humidity levels to stay between 50% and 60%. This is slightly higher than the ideal humidity level for the home and higher than the average home during the winter months.

If you have a special room for your plants or an attached greenhouse or sunroom, using a humidifier in that space can greatly improve the overall look and your potted plants’ health.

Learn More: Where you should place your humidifier for maximum effectiveness.

Types of Humidifiers

Humidifiers are often broken down into two categories: warm mist and cool mist. But, in terms of how humidifiers work, there are actually five types you need to be familiar with. Some of these put out cool mist, while others only release warm mist.

Ultrasonic Humidifiers

a woman sitting next to an ultrasonic humidifier

Ultrasonic humidifiers are the most popular choice in terms of personal humidifier units. These appliances work by vibrating water at ultrasonic speeds to create water vapor that then rises into the air.

Technically speaking, ultrasonic units are cool mist producers. But there are some models with heating elements to create a warmer vapor. This vapor, unfortunately, does not get as hot as true warm mist humidifiers. 


  • Very energy efficient 
  • Will not scald
  • Affordable


  • Can aerosolize minerals and pathogens
  • Require frequent cleaning 
  • Require distilled water


an evaporative humidifier on the floor

Evaporative humidifiers add moisture to the air by pulling water into a wicking filter. The moisture in the wick is then evaporated into the air using a fan.

These types are considered cool mist humidifiers, but they don’t actually produce visible mist. Since the mist is incredibly fine, this type of humidifier does take longer to raise the humidity in the room than others. On the plus side, they are less likely to cause condensate on nearby surfaces.


  • Affordable
  • Do not aerosolize minerals or pathogens
  • Can be used with tap water 
  • Will not scald


  • Filters must be replaced often
  • Must be cleaned regularly 

Steam Vaporizers

a steam vaporizer on the bedside table

Steam vaporizers are true warm mist humidifiers. These units boil the water in the reservoir to create steam. The steam rises through an open air space, which allows it to slightly cool before moving out of the appliance and into the air.

Care needs to be taken when using a steam vaporizer since the water inside can be very hot. Even the surfaces of these units can get hot to the touch, making them unsuitable for use in children’s rooms.


  • Do not reduce the temperature in the room 
  • Water is purified before vaporization
  • Do not need to be cleaned as often


  • Use a lot of energy
  • Water inside can scald
  • Outside surface can get hot

Impeller Humidifiers

an impeller humidifier releasing vapor

Impeller humidifiers use spinning discs or belts to fling water into the air of the chamber. Simultaneously, a fan draws air through the unit and out the other side, effectively drawing moisture along with it.

These types are less popular but still come with some benefits. They are very safe for children because there are no heating elements and they also tend to be very affordable.


  • Will not scald
  • Very affordable


  • May expel pathogens
  • Require frequent cleaning
  • Not as energy-efficient

Central or Whole-Home Humidifiers

Whole-home or central system home humidifiers come in two different varieties: evaporative and steam generating.

The basic process of both is similar to the smaller-scale versions featured above. The main difference is that these units are very large and integrated into your home’s central heating system. In some cases, the hot air created by your furnace may be used directly to create the water vapor in the humidifier.


  • Increase humidity throughout your entire house
  • Will turn off and on as needed to maintain healthy humidity 


  • Very expensive to install
  • Draws a fair amount of power
  • Can be difficult to maintain 

To learn more about the most popular types of humidifiers and how to choose the right type for your home, check out the video below.

What Are the Risks of Using a Humidifier?

Humidifiers have many uses throughout the home and come in many different varieties, making it easy to find the right solution for your needs. Unfortunately, using a dehumidifier also comes with some risks.

The risks of some types are greater than others, but all need to be used with caution to avoid over humidifying your home.

Introducing Aerosolized Minerals Into the Air

woman adding distilled water to a humidifier

The most immediate concern with using a humidifier is the potential to aerosolize minerals and pathogens into your air.

As water is turned into vapor inside ultrasonic humidifiers, minerals, mold, and bacteria present in the water can also be pushed out into the air. 

Aerosolized bacteria and mold spores have the potential to cause illness. Those sensitive to mold may develop allergic rhinitis and other allergy symptoms. Bacteria can easily get into the lungs and cause pneumonia and other serious infections.

Minerals that are pushed into the air create a fine white dust that often covers the top of the unit and nearby surfaces. This dust can easily be breathed in, which can cause symptoms of chronic lung disease and other problems associated with mineral toxicity, according to the Children’s Hospital of Colorado.

Note: Luckily, there’s an easy solution to all of these problems: only use distilled water in your humidifier. Distilled water is free from minerals, pathogens, and chemicals and will only produce a fine, 100% water mist when used in a humidifier.

Introducing Mold and Bacteria Into the Air

a woman removing the water reservoir of a humidifier

Mold and certain types of bacteria thrive in dark, moist environments like what is found inside your humidifier. Even if you use only distilled water, mold spores and bacteria cells can be introduced into your humidifier through surface contact. If the unit is not cleaned often enough, these single-celled organisms will begin to grow and form colonies.

If mold or bacteria are growing inside your humidifier, then they are likely also being introduced into your air through the action of fans and misters. The only humidifier type that is immune to this is a vaporizer since the water is boiled during the vaporization process.

Note: It is imperative to keep the tanks and water-contact surfaces clean. This means scrubbing them with soapy water or vinegar at least once per week. You should also take them apart and completely dry the surfaces before storing them.

Promoting Mold Growth and Dust Mite Activity

Humidifiers are great for introducing moisture to dry environments, but they can also introduce moisture to already moist environments. When your home becomes too humid, you run the risk of encouraging mold growth and increasing dust mite activity.

Both of these unwanted house guests thrive in humid environments (anything above 60% humidity). Overrunning your humidifier can quickly push the relative humidity in your home over this mark. Worse still, condensation on walls and window sills from humidifier vapor can actively feed mold growth on these surfaces.

Note: To be safe, you should constantly check humidity levels when using your humidifier. Aim for levels between 40% and 50%. Once you reach that top mark, turn off the unit until the level drops again.

If your house is frequently over humid, you may be better off getting a dehumidifier.

The Bottom Line on Humidifiers

Humidifiers are useful, practical appliances to have on hand. They can help you feel better when sick, prevent illness from spreading, reduce snoring, and make you and your house plants feel more comfortable when the air is dry.

But these machines also come with some risks, such as aerosolizing minerals and increasing mold growth and dust mite activity. Luckily, minimizing these risks is easy to do so long as you use the right type of water, keep your unit clean, and monitor your home’s humidity levels.

Still have questions about humidifier risks and uses? Comment below!

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Sara Seitz
Sara Seitz is a freelance writer and novelist. She lives with her husband and wildling toddler in Colorado where she spends her days working on their house, gardening, and reconnecting with nature.

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