What Does a Humidifier Do?

You probably didn’t know your humidifier could do this.

We all know that a humidifier raises the humidity — but how exactly? And are there any benefits of this for our health?

Humidifiers are a must-have in many households during the winter or flu season due to low humidity levels. It’s recommended to keep the humidity between 30 and 50 percent to create a well-balanced environment (1). However, when the humidity drops below 30, it can cause certain issues like dryness and congestion.

How Does a Humidifier Work?

Humidifiers emit water vapor or steam into the air to increase the moisture. They’re straightforward devices that consist of a tank to hold the water and a base for the controls.

There are five main types of humidifiers:

1. Ultrasonic Warm or Cool Mist

Cool mist humidifier on table

This type of humidifier creates a fine mist that is emitted into the air and evaporated soon after. It consists of a small metal diaphragm that vibrates at ultra-sonic speed — hence the name. Consequently, it creates very small water particles that form the mist.

Depending on the model, some will heat the water to 104 degrees Fahrenheit — warm mist. Others, though, stay cold — cool mist. Some more high-end humidifiers offer the option of warm or cool mist.

2. Vaporizer

Vaporizer on table

These contain a heating element that boils the water to create steam, which is then released into the air. The steam should be cool by the time it reaches you. However, do refrain from standing too close to the device while running.

As a bonus, some vaporizers — such as the Vicks — offer the option of adding an additive to increase its effectiveness.

3. Evaporative Cool Mist

Evaporative Cool Mist humidifier

Evaporative humidifiers work by drawing dry air in over or through a moist wick in the tank. The water within the tank will begin to evaporate, and as the vapor increases, moist air is blown back into the room. During the process, heat is removed from the air, resulting in cooler air being emitted back into the room.

4. Air Washer

Air Washer

These devices work simultaneously to purify the air as well as humidify it. They work by drawing air in and “washing” it using rotating discs or mats. As the air is scrubbed, large particles of dust, pollen and other impurities are removed. Air washers produce a clean and cool mist that effectively increases the humidity.

5. Whole-House

A whole-house humidifier can humidify your entire home at one time. There are different types, including evaporative and the more expensive steam model. These are installed directly into your HVAC system.

How Is Humidity Measured?

When measuring the humidity, we often use a term called “relative humidity.” The relative humidity is the ratio of moisture found in the air compared to how much moisture the air can hold. Temperature plays a significant role in humidity levels since hot air can hold more moisture compared to cold (2).

A hygrometer is commonly used to measure the relative humidity of a room. There are usually separate devices for indoor and outdoor use. Hygrometers measure the temperature and moisture level to give you exact results, such as 40 percent humidity (3).

What Affects the Humidity Levels?

Three factors can affect the humidity levels within your home:

  • Temperature: As mentioned above, when the air temperature rises, the more moisture it can hold, consequently raising the humidity. On the other hand, as it gets colder, the air is unable to hold as much moisture, making it drier.
  • Ventilation: We utilize our HVAC systems to improve our indoor air by removing hot air and replacing it with fresh air. Inadequate ventilation can lead to dampness and mold as the humidity and temperature rise.
  • Your house: Both the airtightness and building materials of your home will significantly impact the humidity. Good airtightness enables you to control the temperature and ventilation better. Some building materials, such as reinforced concrete, can make it tricky to control condensation. In comparison, newer materials like wood-based cellulose fiber absorb moisture (4).

What Are the Benefits of Humidifiers?

During the winter, the air tends to be cold and crisp — cue the chapped lips and flaky skin. However, with a humidifier on hand, you can get through winter without feeling moisture-deprived. Here are a few benefits of humidifiers:

Prevents Snoring

Whether you’re the snorer or the person who has to listen to it all night, it can be very frustrating. If you tend to breathe through your mouth while sleeping, you’re likely going to be waking up feeling dry.

Run a humidifier during the night to help soothe your throat and nose from the dryness. It will help you to sleep more comfortably while also minimizing snoring. Additionally, running the humidifier during the day as well helps your throat to stay moist.

Beneficial to the Home

It’s not only you and your family who can benefit from a humidifier; your home can too. If you have wooden floors or furniture, keeping the humidity balanced can help the wood to last longer. Furthermore, if you have houseplants, these will benefit from a little extra moisture in the air.

Prevents Static

Ever noticed how frizzy your hair can get during the winter? Or do you notice static electricity when removing the sheet from your bed? Dry conditions in your home can cause this.

Static electricity isn’t just annoying; it can also be dangerous if it builds up as it can damage certain electronics. Higher humidity can help to prevent or lessen static.

Helps to Prevent Spreading of Airborne Viruses

In recent studies, it was shown that airborne viruses were least likely to spread when the humidity was at least 43 percent. The study showed that nearly 85 percent of viruses were virtually ineffective in more humid conditions (5).

Moisture can prevent the movement of germs since they drop to the nearest surface when combined with moisture. As a result, it’s more difficult for the germs to spread through the air. This gives you a chance to clean and remove them.

What Are the Disadvantages of Humidifiers?

There are many advantages to humidifiers, but they aren’t without flaws.


Although humidifiers are highly beneficial, they can become a breeding ground for mold and bacteria. This isn’t just filthy to look at; it can also cause the bacteria and mold to spread through the air. As the water in the tank turns to vapor, so do the contaminants.

Keep In Mind

It’s crucial to clean your humidifier regularly and change the water before using it. Never leave water standing in the humidifier for long periods — always clean and dry the tank before storing it.

High Humidity

If your air is dry, using a humidifier is beneficial. However, if you overuse it, you can create a new problem: high humidity.

According to the EPA, humidity levels of 60 percent and more are considered high. With high humidity levels, dampness and condensation are likely to occur. This can lead to dust mites, mold, mildew and other indoor allergens (6).

Take Note

If you’re using a humidifier, you should also have a meter to measure the humidity, such as a hygrometer. Keep track of the humidity levels in your home and only use the humidifier if necessary.

Does a Humidifier Help With…

A Cold?

Whether or not humidifiers help when you’re suffering from a cold is conflicting. Many parents use cool mist humidifiers to help ease congestion and stuffy noses. However, research has shown that warm mist humidifiers aren’t as effective in treating cold symptoms (7).

Keep In Mind

Always use a cool-mist humidifier around children. If they get too close to a steamer or vaporizer, they can get burned.


Although humidifiers can help to ease coughing, they can also trigger asthma. This is due to the risk of dust mites and other indoor allergens thriving in more humid conditions. Furthermore, if the tank has mold or mildew, this could spread through the air, causing you to inhale it (8).

Dry Skin?

As soon as winter hits, many people begin to feel dry and chapped. This is because the human body is made up of approximately 50 to 60 percent water. When we’re exposed to dry conditions, the moisture is pulled out of our bodies, leaving us dry, flaky and chapped.

Run a humidifier to keep the relative humidity at a balanced 50 percent for your body to be comfortable. In addition to the humidifier, it’s also crucial to drink enough water during the day to make up for what’s lost.


When you get a bad cough or chest cold, experts advise that taking antibiotics won’t do much. So what can you do? According to the Centers for Disease Control and Prevention, using a clean cool-mist humidifier or vaporizer can help to ease the symptoms (9).


Similar to asthma, common indoor allergens thrive in humid environments. Therefore, by increasing the humidity, you can trigger allergies. Additionally, if mold and mildew are growing within the tank, it will spread through the air (10).

What Humidity Should I Set My Humidifier To?

Humidity levels below 30 are too dry, and above 60 are too high. For the optimal humidity, we recommend setting your humidifier to 40 or 45 percent.

How Much Does a Humidifier Cost?

Whole-house humidifiers can cost between $100 and $700, depending on the type.

Evaporative humidifiers are less expensive compared to steam humidifiers.

With whole-house humidifiers, you also have to consider installation fees. These can range between $100 and more than $1,000 (11).

Small humidifiers can cost anywhere between $15 and $100, depending on the model and size.

Cleaning and Maintenance of a Humidifier

Taking care of your humidifier is crucial to prevent air contamination. Daily maintenance includes emptying and refilling the tank. It’s recommended that you flush the tank using white vinegar once or twice a week to remove potential mold or mineral build-up.

When needed, you can sanitize the tank using either bleach, peroxide or pure vinegar. Always unplug the humidifier before cleaning or doing maintenance. Never use other chemicals to clean the tank since it can be damaged or cause the chemicals to spread through the air.

Humidifiers Have Their Place

We all hear about people who use humidifiers during the winter to ease congestion and other issues like dry skin. However, do you know what a humidifier actually does?

How a humidifier works depends on the type. There are five main types of humidifiers, including evaporative and ultrasonic.

Although humidifiers are very beneficial, they can do more harm than good if not used properly. It’s crucial to keep your humidifier well-maintained to avoid mold and bacteria from building in the tank. Nonetheless, by using a humidifier, you can easily keep your home environment comfortable during the colder months.

Headshot of Matthew Sullivan

About the Author

Matthew Sullivan

Matthew is a freelance writer with several years of experience in DIY and HVAC. For as long as he can remember, Matthew has always found great pleasure in taking things apart and learning how to put them back together.