How To Tell If You Need A Humidifier: A Helpful Guide

If you’ve ever suffered from weather that’s dry, cold, or both, then you’ll know just how harsh the effects of dry air can be. If you suffer from allergies or asthma, then dry air will be one more thing that will make you feel absolutely miserable!

But don’t fret too much! There’s a great – and affordable – solution. Read on as I’ll explain what humidity is, how you can tell if you need a humidifier and how they work, too.

Infographic – How to know if you need a humidifier


The quick answer

Just want the basic answer? There are 2 simple ways to know if you need a humidifier:

2 Ways To Check If You Need A Humidifier
  1. By recognizing the effects of low humidity (dry air) using related symptoms
  2. Measuring your air’s dryness using a humidity gauge

If you recognize low humidity by the signs or if your humidity gauge shows 30% (or less), you need a humidifier.

Why do I strongly recommend using a humidity gauge? Because we can’t always rely on how our bodies feel at any given time to know the air condition. It’s not a reliable or consistent way to know.

Don’t rely on your senses only

For many reasons, our bodies fluctuate in sensitivity and at times the air is actually warmer, colder, or drier than we think it is. It’s better to have a reliable and easy-to-use way to check the air instead.

I strongly recommend picking up an inexpensive humidity gauge which I go into more detail about below. I’ll also list the symptoms you can use to recognize when a humidifier is needed.

What is humidity?

Example of condensation on a glass window due to humidity

Condensation on cooler items (in this example a glass window) is simply a buildup of moisture – or “humidity” – in the air. When cooled, airborne moisture often collects as you see here. It’s one reason windows fog up after a rain or its foggy outdoors following bad weather.

In the simplest terms, humidity is the amount of water vapor that is present in the air given the current temperature conditions.  

There’s actually a lot more science involved when it comes to humidity and how it relates to air temperature, but for our purposes, I’ll keep it fairly simple.

Humidity examples

Have you ever been driving home and come across a dense fog that makes it hard for you to see? That’s a great example of what happens when there’s a lot of water vapor in the air: the humidity has increased a lot.

As you may remember, after heavy rains there’s a lot more moisture in the air, causing your windows to fog up and the environment feels a bit “muggy.” It’s because the humidity is higher than normal.

Some geographical areas like Arizona or California have dry climates and there’s almost never much humidity. This is why wildfires are so hard to put out in those areas.

Similarly, wintertime and heavy indoor heating use are 2 of the largest causes of low humidity. Although you may have never known, using a heater indoors commonly lowers the humidity to levels that are hard on your body.

Air is already dry during wintertime as the moisture is pulled from the air due to the cold temperatures. Using a heater inside to keep warm makes it even worse!

Dry air (low humidity) signs to know

Here’s a brief list of some of the most common – and reliable – ways to know if you are is too dry and a humidifier can give relief. While some may seem obvious, not everyone understands why they happen.

Symptom/Condition Notes and description
Static electricity Static electricity increases greatly when the humidity is too low, as static charges are no longer blocked by normal moisture levels. Static electricity is potentially destructive as the charge built up can be several hundred volts and is enough to destroy electronics.
Dry skin, nose, eyes, throat Internal passageways dry up as mucous membranes cannot support healthy moisture levels. This leaves the body susceptible to sickness and irritants. Additionally, during colds or flu the body cannot recover as quickly. Eyes may lose moisture and cause discomfort. Skin becomes susceptible to cracking due to dryness and skin problems may appear.
Nosebleeds Nosebleeds are also due to insufficient moisture and mucous levels in your nose. This leaves blood vessels more susceptible to bleeding due to skin breakage. Random nosebleeds are often a sure sign of exposure to excessively dry air for extended periods.
Increased allergies Dry air allows allergens in your home to move more freely. Increased allergy symptoms may appear. Sneezing and coughing also tend to increase as well as more difficulty sleeping.
Plants become dry If indoor humidity is too low this causes problems for plants, too. When the air is too dry, soil can lose moisture more rapidly and leaves are subject to drying out. Plants have a harder time remaining healthy and growing, similar to cold extremes outdoors.
Pet problems Low humidity indoors can cause sneezing and skin problems for pets. Wheezing, sneezing, and extreme thirst are some signs the humidity is too low and needs attention.
Home material damage Low humidity extremes can cause damage in your home’s materials indoors such as wallpaper peeling or wood floors that warp. Some furniture can dry out and need a moderate moisture level for best preservation.

Physical signs such as frequent nosebleeds or a cold that just doesn’t seem to get better can also mean that your house is too dry.

Do you have a lot of static electricity around your home? If your paint or wallpaper is peeling or your wood floors are warped, that could also be a sign too much dry air in your home.

How dry air affects you

Image of dry hand skin cracking due to dry air

One of the most common effects of dry air is dry skin, resulting in many different problems. As your skin loses moisture and remains in dry air it will become easier to damage, skin conditions may begin to appear, and cracking can occur.

The human body is very sensitive to humidity. Our skin needs a moderate & comfortable humidity level to get rid of moisture when we’re warm in order to be able to cool off.

Likewise, our skin and internal breathing passageways need more moisture (we need to increase the humidity level) when the air’s too dry.

The effects of dry air

When humidity approaches lower levels, causing dry air, you’ll feel colder than it actually is.

Not only that but your skin may become get itchy and flaky. Other skin problems may occur as well because when the epidermis (outer layer of skin) loses its healthy level of moisture it’s much more vulnerable to problems.

Your eyes will also become irritated and dry. People using contact lenses or who have eye problems may become more and more uncomfortable. For people with asthma and other health problems, this can become particularly bothersome.

Without a better solution, you’ll be left to temporary, and annoying, remedies like constantly applying lotion. Using a humidifier is a far better way to deal with it when you’re indoors.

Low humidity and sickness

Did you know? Your chances of becoming sick with a cold, flu, or bronchitis increase in dry air. Your mucus that normally traps infections finds it harder to catch things and prevent entry into your body.

If you’re already sick, dry air will cause even more havoc in your nose, throat, and lungs. Colds and sore throat conditions take longer to recover from as well.

Dry air conditions will also make you more susceptible to getting sick by others. Think about the virus that was going around your workplace or how when one of your family members got sick it seemed to be passed to everyone.

Effects on babies and children

Image of a little girl coughing from sickness, with her mother

Dry air is especially tough on children, as their young lungs, throat, and nose aren’t as developed as adults. Babies also breathe in more air per volume for their size than adults do! That means, unfortunately, they’re more likely to get sick or suffer when conditions around them are poor – like very dry air.

Your baby will likely be even more affected by being exposed constantly to dry air. Of course, the biggest risk is their increased likelihood of getting sick. And we all know how easily kids spread germs to each other during the day and at school.

Symptoms like coughing, nosebleeds, and stuffy nose are some of the most common.

Dry air causes children to take longer to recover from sickness and can even cause them to experience respiratory problems.

When a baby is experiencing physical discomfort due to a sore throat or dry nose, that means they’ll have an even harder time sleeping, too. If they aren’t sleeping, then neither are you!

Some other signs to recognize if you need a humidifier for your child’s room is newly dry skin and an increase in rashes becoming worse.

How to know what humidity level is best

Relative humidity comfort scale image diagram

Above: A relative humidity chart showing the general range of moisture in the air and what’s considered good for humans and animals. When the humidity falls below the comfort range (about 30%) you’ll need a humidifier to bring comfort back.

When you’re talking about humidity in your home, you may often hear it called relative humidityThis is a more scientific term used to describe how humidity has a close relationship to temperature.

In case you weren’t aware, temperature affects how much moisture the air can “hold.” It’s normally expressed as a percentage. The higher the temperature, the more humidity that is possible, much as you may have experienced in tropical regions.

Recommended Humidity Levels

A relative humidity range between 30 and 50 percent is ideal for your home, although what feels comfortable can vary a bit from one person to the next.

As a general rule, 50% humidity is right for nearly everyone and is a good target. When the humidity is lower than 30 percent, that means that your home is too dry and you need a humidifier.

Note that these are general ranges. You don’t have to get it perfectly matched to one particular number, just close.

(Note: If the humidity is over 50 percent then your home is ideal for mold, bacteria, and even dust mites. That’s not exactly ideal for you and your family! A dehumidifier is your best defense in this case.)

Why using a humidity gauge is smart

ThermPro TP50 humidity and temperature gaugeWith a digital meter, there’s no guessing. Simply glance at it and if it reads around 30% or below it’s time for a humidifier.

You can measure the humidity in your home with a humidity gauge (sometimes called a hygrometer). Even very good ones that are fairly accurate are inexpensive. When the displayed reading falls to around 30% and below you need to use a humidifier.

Most models also display a readout of the temperature in addition to the humidity, making them even more ideal for knowing what kind of air situation you have.

With a digital humidity gauge, you’ll be able to know with confidence the air condition in your home.

Just put it in you or your baby’s room and check it occasionally. It measures the humidity level in real time, so you always know whether you need to turn on the air conditioner (should the humidity be too high) or set up the humidifier for the night.

In my experience, most are very accurate, despite being low-cost. 2%-5% accuracy is pretty typical and just fine for all homes, offices, and even cigar storage.

highly recommend picking one up for several reasons:

  • They’re very cheap ($10-$20 for a great one as shown)
  • Takes the guessing out of knowing when your air is too dry
  • Lets you know immediately when you should turn your humidifier on or off
  • They’re very battery-efficient and don’t need external power

How do humidifiers work?

Image of infant girl next to humidifier releasing mist vapor

Humidifiers use one of several methods to increase the moisture level in a room. Most products sold today fall into one of 2 main categories: warm mist or cool mist.

Still unsure about what a humidifier is exactly?

The purpose of a humidifier is to change liquid water to fine mist water vapor. It then releases this mist or steam into the air, raising the humidity level as it does so.

This causes an immediate level of relief from the dry air in a room and increases your comfort. Honestly, in my experience (when using a good one like I own and recommend) it doesn’t take very long to start feeling an improvement.

Warm mist vs cool mist humidifiers

Warm mist vs cool mist humidifiers exmapleWhile there are a few other types still sold today, the most common (and most popular) humidifiers include two types: Warm mist and cool mist.

While they often look very similar, there are pros and cons to each depending on what your needs are. Therefore it’s important to know the differences.

Warm mist humidifiers

Vicks V745 warm mist humidifier product example image

Warm mist humidifiers often look extremely similar to cool mist. However, there are some differences to know about. For example, warm mist models produce water vapor using steam. Unlike cook mist products, some models also support cold relief additives like drop-in medicated liquids or medicated pads to distribute sinus & cold relief in the air.

Warm mist humidifiers use electricity to produce heat and generate heated water vapor which rises into the air.

Clean water stored in the tank gradually moves through a heating element and vaporizes it. The water is then in a steam-like state and can rise into the air, increasing the humidity.

You can add scent pads or other vapor liquids to some of these types as well. If you’re having cold or flu-like symptoms, asthma, or allergies, you can get extra relief with these steam medications.

Since they produce a warm mist, they can also make your room feel warmer. They’re great for winter or moderate temperature environments and can really help with congestion during sickness.

However, they’re not a good match for warmer climates due to the small amount of heat they add.

Warm mist humidifiers do offer selectable mist levels like low or high. However, unlike cool mist, they don’t typically offer a finely adjustable output using a dial control. Instead, most have a few selectable fixed levels such as low or high modes.

Like cool mist models, when the water is completely used most are designed to shut off automatically. You’ll need to refill the humidifier once it runs out.

They’re fairly quiet during operation also, but cool mist models are even quieter.

Cool Mist Humidifiers

Pure Enrichment MistAire cool mist humidifier featured image

Cool mist humidifiers release vapor using electronic or electro-mechanical devices instead of heat as warm mist models do. They create super-fine water vapor which fills a room.

Cool mist humidifiers create moisture in the air without the need to use heat or warm the water.

This typically makes them more affordable than their warm mist counterparts. A cool mist humidifier will spray cool mist into the air.

You can find two types of cool mist humidifiers. The first, and most commonly sold type, is an ultrasonic design. These work by rapidly oscillating the water, turning it into an ultra-fine mist that rises into the air.

Ultrasonic humidifiers have another characteristic aside from not producing heat: they’re nearly completely silent during operation.Impeller humidifier example imageAn example of an “impeller” type humidifier. It’s a bit of an outdated technology these days but some are still popular with buyers. These types use an electric motor to turn blades in the water and produce a fine mist.

The other type of cool mist design is the impeller type. These use a motor-driven fan with blades that rapidly stirs water to produce mist. Impellers aren’t very common today and they produce more noise than their counterpart.

Another added benefit of cool mist models is that they use less electricity than warm mist models. Additionally, they don’t add heat to a room, so they’re ideal for year-round use, especially in areas with dry, warm climates.

However, they’re not as effective in helping to relieve congestion during cold and flu season.

Summary – Key points to remember

Just remember there are 2 main ways to know if you need a humidifier:

  1. Paying attention to the dry air symptoms I listed earlier and recognizing why they’re happening
  2. By using a humidity gauge to monitor the humidity level around you

If the symptoms you see match some of those I’ve listed, it’s time to use a humidifier. If you’re using a digital meter, use a humidifier when it reads 30% and below.

Remember that 40-60% or so is the ideal range of humidity for comfort, with 50% being a great rule of thumb for most people.

Grant Williams

About the author

Grant is a professional engineer by trade and has experience with both maintenance and do-it-yourself home projects. He enjoys sharing his expertise & ideas with others to help them improve their comfort and quality of life. Read more »

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