How to Choose the Best Humidifier for your Baby

Article By:
Ellen Baker and Juliet Spurrier, MD

Last Updated:
February 3, 2016


Why Buy a Humidifier?

If you live in a dry climate, you may already be familiar with humidifiers. Dry air in particular can really wreak havoc on skin and mucous membrane well-being, particularly in the winter. If you live in a humid climate, you may have the opposite problem with too much moisture in the house and rely on a de-humidifier to prevent mold growth.

Whatever the case, however, as soon as your baby gets his or her first cold, you may be introduced into the complex world of humidifiers. Humidifiers can help loosen the thick, viscous, and sticky mucous that accumulates in your baby's nasal passages and upper airway during a URI (Upper Respiratory Infection). Extra moisture in the air can make the difference between being up all night with your little one, and getting at least a little shut eye. Within a very dry climate, humidifiers can also help keep mucous membranes moist on a regular basis which helps prevent bloody noses and dry, cracked lips. It is also a nice item to have if your little one should develop an episode of croup.

Just as a very dry climate can cause issues with respiratory health and general comfort discomfort such as dry eyes and skin, it can also cause problems within the home, for example, shrinkage of wood floors and furniture, cracked paint on wood trim, and static electricity. Similarly, too humid of an indoor climate can foster condensation, unwanted microbe growth, and mite infestation. What is the proper use of a humidifier to create both a pleasant yet healthy home environment? Well, it turns out that this is quite a loaded question. This article's purpose is to educate you not only how to buy a great humidifier for your child's room but even more importantly how to use it safely.

Safe Humidification Levels for the Home

Debate bounces back and forth between builders, physicians, and microbiologists regarding the proper indoor humidity for both health and prevention of microbial growth. A general rule of thumb is somewhere between 25 to 60%. However, outdoor air temperatures will dictate where in this range is safest. In many parts of the U.S., this will vary from from season to season. Because it is important to have a basic understanding of this if you are going to use a humidifier in your home, we are going to touch upon this topic before digging into the basics. A helpful fact that will guide you throughout this preventive discussion is that cold air can not hold as much moisture as warm air.

Let's begin with a few helpful tips for use with the goal of creating both a pleasant and healthy home environment.
Optimum zones for humidity as they relate to microbe growth and health.
Optimum zones for humidity as they relate to microbe growth and health.
  • Discuss Use with Doctor if Allergies or Asthma — It is important to touch base with your child's doctor before using a humidifier in their room if they have a history of asthma or allergies. While increasing humidity levels can often be helpful, if not aren't used properly, it could exacerbate his/her condition.
  • Use a Hygrometer — A hygrometer is a handy device which measures the indoor humidity. Year round recommended indoor humidity should be in a comfort range of between 25-60% (dependent upon the outdoor temperature). However within this range, the majority of people cannot sense any difference. This is where a hygrometer or simple humidity monitor is helpful. Available for as low as $10, it is an invaluable tool when using a humidifier within the home. Though lower cost hygrometers may have an error rate of +/- 3-5%, they provide very good general information as they allow for basic household trends to be observed. In our in-home, day-to-day testing we used the AcuRite Indoor Temperature and Humidity Monitor.
  • Adjust Humidity Based on Outdoor Temperature — Whether you live in a climate with 1 continual season or one with 2 to 4 distinct seasons that fluctuate between very cold and very warm, being educated and maintaining proper humidity levels within the home based on outdoor temperature is very important.

A general rule of thumb is to keep Relative Humidity (RH) below 60% during the summer and between 25 to 40% during the winter. Most importantly, do not overdo it. Too much humidity will propagate mold growth in the home, oftentimes without even being visible (i.e. insulation within walls).

This informal but very informative 9 minute video produced by Building Science Laboratories interviews John Straube Ph.D., an internationally recognized expert on moisture control. We recommend that you give it a view as it provides both education and answers to some very common questions about indoor RH, relative humidity, and use within the home.

For those of you that would like further understanding of how condensation occurs, how high indoor RH during the winter (with freezing outdoor temperature of 32F/0C ) can produce condensation within walls, Chris Schumacher from Building Science Laboratories answers the question "how do RH and dew point work?". As well, the helpful table below represents various dew points for common air temperature/relative humidity combinations.
Dew Points for Common Relative Humidity-Air Temperature Combinations
Dew Points for Common Relative Humidity-Air Temperature Combinations

Types of Humidifiers

Competing products come in an array of types, we'd like to break this down for you to help give you a brief but better understand what is available. While there are products for either the entire house or a part of it, our comparative review The Hunt for the Best Humidifier focuses solely on single room products for the purpose of use in a baby's room.

Each product's output capacity determines how easily and effectively it can push moisture through a space. Measures of room humidification are usually given in square feet. Maximum square footage for humidification can be an important factor to consider when looking at a room unit, especially if the area you want to humidify is large. On the other hand, if your baby's room is on the small side or you are only wanting to humidify the crib area for sleeping, the square footage measure of room humidification may be less important. So, a product listed as being able to supply moisture to a 500 square foot room should easily be able to meet humidification needs in a room with a smaller square footage.

Depending on the total square footage of the area you would like to humidify, a product with a high output capacity and effective mist dispersion can provide adequate moisture for more than one room, or even for an area of your house. Although many of the products in our comparative review give an objective humidification coverage in square feet, we did not seek to determine how each company came about this measurement. Instead, we consider it more of a general statement of output capacity, rather than a guarantee that it could provide consistent humidity throughout a given square feet of space.

Central Humidifier

A central unit's purpose (below left) is to humidify an entire home. They are units that attach directly to a home's forced-air heating system and push moisture through the air vents to achieve an overall increase in humidity.
The Aprilaire 700 is an example of a whole-house humidifier.
The Essick Air 821-000 evaporative console humidifier can humidify up to 1 900 square feet of space and sits on rolling casters.

Console Humidifier

Console units (above right) are free-standing products that can humidify a large portion of the home. However, they are not easily portable.

Single Room Humidifier

Single room products (below) are smaller units (typically ultrasonic or evaporative, more on this below) that can increase the humidity in a room or a smaller section of your house. Single room units are particularly helpful during a respiratory illness when congestion makes it difficult for baby to sleep. However, they can also be helpful year round to maintain comfortable levels of humidity.
The Sunpentown SU-4010 in action.
The Sunpentown SU-4010 in action.

Steam Vaporizer

Steam vaporizers humidify via warm mist. They use electricity to boil water until it turns into steam vapor. However, because they produce hot steam internally, they are not recommended for use with children to prevent burn injury. Many vaporizers also offer the ability to use medicinal inhalants or essential oils in a separate reservoir or on a pad, and distribute them into the air during operation.
Vicks Warm Steam Vaporizer V105SG with a claimed 1 Gallon capacity heats water into steam  so it comes out hot. As such  we do not recommend warm vaporizers for a child's room. This particular unit can be used in conjunction with Vicks VapoSteam or Kaz inhalant.
Vicks Warm Steam Vaporizer V105SG with a claimed 1 Gallon capacity heats water into steam, so it comes out hot. As such, we do not recommend warm vaporizers for a child's room. This particular unit can be used in conjunction with Vicks VapoSteam or Kaz inhalant.

Aromatherapy Vaporizers

Aromatherapy vaporizers (below left) diffuse essential oils into the air without heat. Some models use ultrasonic vibration and a filter pad without water, and some require that you put your chosen fragrance directly into a small water reservoir. These are great to make your room smell pleasant, but neither noticeably raise nor maintain a given humidity level in a room.
Aura Cacia Aromatherapy Vaporizer Kit
Air-O-Swiss Ultrasonic Travel Humidifier 7146

Travel Humidifiers

Travel products (above right) are nifty devices that you can take with you on the go. Their size makes them easy to fit in a suitcase, but also limits their effectiveness. These units are great to place on a nightstand during a hotel stay, but do not offer the power or features that are necessary for daily and continuous use.

Cool Mist vs. Warm Mist

Another option to consider is whether you prefer cool or warm mist output. No product we tested actually refrigerates the water before putting in into the air, so "cool" mist just means that the mist is produced using room temperature water. It will feel cool due to the evaporation that occurs as soon as the mist reaches your warm skin. Cool mist products can be more cost effective because they do not require extra energy to run a heating element.

Warm mist models either heat the water enough so that it turns into steam and rises naturally, or heat the water to a set temperature well below boiling before using another process such as ultrasonic vibration to push the mist into the air. Some people prefer warm mist because they find it makes the air feel less chilly, but this tends to be more of subjective feeling rather than an observable temperature difference. You may appreciate a warm mist product in an especially cold room.

Most products can produce cool mist, some produce only warm mist, and a few models can even do both. In our testing group, all the products produced cool mist, and two models offered an added warm mist feature. These two models, the Boneco U7147 Digital and the Sunpentown SU-4010, created warm mist by heating the water to around 104 degrees before using ultrasonic vibration to create the mist.

While we are on the topic of warm mist units, a note of caution: we at BabyGearLab feel that using a true warm mist products (one that heats the water to boiling to create steam), is not a good idea when a small child is involved. Boiling water around a curious baby or toddler creates a safety hazard that we do not feel is worth the potential problems it could create. Even with the two models we tested that only warm the water, we recommend keeping them well out of your precious little one's reach to avoid the possibility of contact with a heating element.

Ultrasonic vs Evaporative

Ultrasonic products are the current popular favorite as far as humidification technology goes. They work by vibrating a small plate at frequencies above what the human ear can hear (thus, the name ultrasonic) to break up water into tiny mist particles that easily float into the air. Ultrasonic units are quiet and efficient, but they also produce the dreaded white dust which you can read about below in the section on cleaning and maintenance.

Evaporative humidification is another humidification technology currently available, although it is less prevalent than it used to be. Evaporative products used to be much more popular than they are today: check out this 1991 article from the New York Times when evaporative wicking products were the latest thing.

Luckily, evaporative units don't experience problems with white dust, but they do have some of their own problems. Evaporative products work by sucking air through a water-saturated wicking filter. This requires a powerful fan (which can be noisy), and a filter with a large surface area (which requires more space than a tiny ultrasonic vibrating plate). Finally, the wicking filter on most evaporative units requires regular replacement. Evaporative wicking filters do a great job of trapping and collecting minerals from the water so they are not put into the air, but over time, these mineral deposits prevent the filter from wicking properly and causes the product to lose effectiveness. Regular replacement of filters should be factored into the overall cost of these units.

Tap Water versus Distilled or Filtered Water

First of all, why does it matter what kind of water is used? Well, it does make a big difference and allow us to tell you why. Tap water contains minerals such as Sodium and Phosphorus. Water quality varies from region to region with some areas having soft water with low mineral content, some average mineral content, and some hard water with high mineral content. Tap water tends to deposit hard mineral deposits within the humidifier that are difficult to remove (much like the cumbersome ring in the toilet bowl). More worrisome, however, is that these hard mineral deposits become breeding grounds for microbial growth of bacteria and fungus. Furthermore, tap water minerals are dispersed by the every more popular ultrasonic units in a fine mist (a.k.a the air you breath), often also seen on surfaces within the room as "white dust." Remember that ultrasonic vibrating plate? Not only does it turn water into mist, but it also breaks up any minerals present in the water and invites them along for the ride. Although these mineral particles are very small, research has found that they may affect respiratory health as seen in this case study. Furthermore, no one wants the extra job of attempting to clean a layer of white dust from furniture and carpeting.

However, there are a few ways to avoid problems with minerals in tap water:
  • Use a Filter — Evaporative units cannot be operated without a wicking filter which requires regular replacement. Basic ultrasonic units do not require a filter for operation, but adding one can be very helpful in reducing white dust if you are using tap water. In turn, they can also reduce mineral deposition within the product itself which over time can be very difficult to remove but also provide a breeding surface for microbial growth
The Boneco U7147 comes with two water-filtering devices. An ionic silver filter cartridge (left) and a Hydrocell using activated carbon technology (right). This unit also provides a small cleaning brush (center).
This is an example of how mineral deposits collect over time when using unfiltered tap water in a humidifier. They are difficult to remove and provide an easy surface for microbial growth.
Mineral deposition in the internal workings of a humidifier becomes very difficult to remove.
  • Use distilled or filtered water — To reduce the presence of white dust, you should distilled water or highly filtered water from a reverse osmosis or multi-stage filter system. Most manufacturers are aware of the problem of white dust and encourage steps for prevention; in fact, all eight of the ultrasonic products we tested recommended the use of distilled or filtered water. Some manufacturers offer additional ways to reduce or avoid white dust by including a demineralization filter or by offering one as a separately-purchased accessory.

We were concerned enough about white dust that we decided to perform our own in-house white dust tests. The pictures below show a side-by-side comparison of the white dust produced by the Duux (lower center left), the most prolific white dust producer and that produced by the Safety 1st 360 (lower center right), a less prolific producer. In this test we used hard tap water. We only used a filter if the unit had one included in its box. Some products such as the Duux and Safety 1st are filterless designs. Others such as the Crane Drop Shape and Crane Adorable have filters available only as accessories to purchase separately. Keep in mind that these photos use special lighting to capture and dramatize the amount of dust produced by each unit, making comparisons easier. And, to further emphasize our point, it is helpful to view the photo for the only evaporative unit in our testing group, the Honeywell 350 (lower right) which produced virtually no noticeable white dust accumulation due to the absence of ultrasonic vibrations in this unit.
These props were used on a black background during humidifier white dust testing to help visualize the amount of dust produced from humidifier to humidifier.
Our white dust test results for Duux Ultrasonic. The Duux produced noticeably more white dust than any other humidifier in our test. In this test we run 2 gallons of hard water through each humidifier  and collect dust on a black sheet. The photography lighting dramatizes the amount seen visually.
Our white dust test results for the Safety First 360. In this test we run 2 gallons of hard water through each humidifier  and collect dust on a black sheet. The photography lighting dramatizes the amount seen visually  which was actually very slight.
Our white dust test results for the Honeywell 350. In this test we run 2 gallons of hard water through each humidifier  and collect dust on a black sheet. The photography lighting dramatizes the amount seen visually  which was actually very slight.

Qualities to Look For

Deciding on a unit that is not too big, not too small, works well, and is durable, stylish, and doesn't sound like a steam train blowing through your bedroom all night long can be tricky! To help you make your decision, we considered the following areas when looking at competing products:

Ease of Cleaning

For each product, we followed the manufacturer's instructions for cleaning and maintenance exactly as written. For some models, this meant daily emptying and rinsing of the water. For other models, this meant a weekly cleaning using vinegar or bleach. Following manufacturers instructions will not only allow you to maintain your product's warranty, but it will also ensure that you are doing the most you can to prevent microbe growth.
Parts of the Crane Drop Shape water tank can be cleaned with a brush  but not all surfaced on the inside can be accessed for cleaning.
Parts of the Crane Drop Shape water tank can be cleaned with a brush, but not all surfaced on the inside can be accessed for cleaning.

Daily Maintenance
Some products such as the Crane Adorable and the Safety 1st 360 explicitly called for daily emptying and refilling of the water tank and basin in the instructions. When you are using a product continuously, this is not as demanding as one would think. We at BabyGearLab thought it was best practice to perform this task daily or at least every other day whether or not it said to do so in the instructions. If you bring the entire unit to the sink with you during refills, it only takes a few extra seconds to rinse out the base. Daily rinsing allows you to inspect the surfaces for unwanted colors (meaning microbe growth) and alert you to when the product needs a little extra TLC.
The base of the Crane Adorable should be emptied daily.
The base of the Crane Adorable should be emptied daily.

Weekly Maintenance

In addition to a daily check-up, humidifiers need a thorough cleaning once-per-week. This weekly cleaning may require wiping down with a cloth, cleaning parts with a small brush, and using a cleaning solution such as vinegar or diluted bleach. Some products require more specialized care than others during the weekly cleaning. The Boneco U7147 Digital takes the cake in this area: the manual recommends changing the water weekly, plus using a specific cleaning solution that you must buy from the company every other week. The Boneco even has a cleaning indicator light that reminds you of this special bi-weekly task and requires you to reset it every two weeks before the unit will operate again.


When considering effectiveness, it is important to look at output strength, capacity, and duration.

Output strength

Output strength is a measure of its ability to raise and maintain humidity levels in a given space. You may not need a product with the highest output strength if your goal is to provide extra moisture to the air surrounding a crib. Some products can be too powerful for very small spaces. On the other hand, a product with weak output strength is much less likely to be able to compensate for periods of extremely dry air or to provide adequate and consistent humidity to a larger area.


Tank capacity becomes very important if you are operating it over extended time periods such as throughout the night. A product with a small tank capacity will require extra footwork for refillings. For continuous operation, large tank capacities are ideal.


Duration is somewhat related to tank capacity, and also to the selected mist output setting. A product with a large tank capacity can operate for a longer duration without running out of water. The ability to control mist output allows you to control duration as well. For example, if you select the highest mist output setting, not only will you use up the water in the tank more quickly, but you might also encounter wet floors from the excessive mist output.


Ultrasonic units are known for being very quiet and, with the exception of the Crane Drop Shape which had a high-pitched whirring noise, the majority of our tested ultrasonic units had a very quiet machine-type noise with occasional bubbling sounds. Evaporative products are less quiet because they require the use of a fan. When looking at noise level, you will want to consider whether you are okay with fan noise. Two of the units we tested, the Honeywell 350 and the Vornado Ultra3 used a powerful fan, but some people may find that the added white noise of the fan helps baby to sleep.

Ease of Use

This was our final rating area and included a careful consideration of weight, bulk, and footprint, as well as features and design.

Weight, bulk, and footprint
The Crane Drop Cool Mist Humidifier is compact and lightweight.
The Crane Drop Cool Mist Humidifier is compact and lightweight.
A portable product should be easy to carry from room to room, as well as to the sink for refillings. The ideal portable humidifier should be lightweight, compact, and have a small footprint so that it can easily fit on a night stand or dresser. The size and shape is also important when you are thinking about refillings. Can the tank fit under the faucet in a kitchen sink? Will the base fit in the sink for cleaning? We found that most of the products we tested did not fit in a typical bathroom sink for refillings.


Features are any extra perk that might come along with the basic functionality. Through testing, we found some features to be essential and some to be just "nice to have." Features that give you control over moisture output are essential. If you are planning to use a product in different seasons over a wide temperature range, you will need the ability to control the amount of humidity it puts into the air. The products in our testing group offered this feature through continuously variable mist adjusting knobs, fan speed, and even through the ability to self-monitor and maintain a specific humidity level using an internal hygrometer.

Features such as a night light, a warm mist option, and auto shut-off timers fell into the "nice to have" category. These features can make life more comfortable and do add value, but they may not be a necessity. We also encountered some features of questionable benefit in our testing. For example, we couldn't find any scientifically-proven function to the Optimus U-31002's permanent ceramic filter, and we were also uncertain about the effectiveness of the UV light in the Honeywell 350.
The Optimus U-31002 offers a night light as an additional feature.
The Vornado Ultra3 water tank requires at least one hand to balance it during filling.


When we look at design, we consider how a product's overall package makes it easy or not so easy to live with on a day-to-day basis. A product with a lot of extra features may not be considered well-designed if its controls are confusing and require extra steps to access certain functions. Similarly, a product that doesn't offer the basic functions, or presents problems when attempting to use basic functions (such as a water tank that doesn't balance on its own during refills) would also receive low marks for design.

Extra Features and Modes to Consider

As mentioned above, extra features that you may want to consider include a night light, warm mist option, and an auto shut-off timer. If you want to consistently maintain humidity within a narrow range, you might also want to look for a product with an internal hygrometer that controls mist output.

Helpful Accessories

There are a few extra accessories that can be very helpful in your quest to maintain a clean and functional humidifier. A bottle brush with a foam tip works well to clean tank insides. For this task, we used the Munchkin Bottle and Nipple Brush. For tiny nooks and crannies, you will want a small brush designed to fit in tight spaces. We used Dr. Brown's Natural Flow Cleaning Brushes, but something similar will work just as well. Based on each product's maintenance instructions, you might also need white vinegar and/or bleach to use during weekly cleanings. Finally, if you choose an ultrasonic unit that does not come with a demineralization filter, you will want to purchase distilled water or use a filtration system to reduce mineral content in the water. If you will be using tap water, look for a filter cartridge that may be available to purchase separately.
The Munchkin Bottle and Nipple Brush
Dr. Brown's Natural Flow Cleaning Brush  4 Pack


After reading this article, your head may be spinning with all of the things you should be considering while searching for a safe and effective humidifier for your child. Not to worry though! Our tests, ratings, and individual reviews looked at all of these areas for every one of the nine products in our testing group. Each product's rating scores and features can be quickly accessed at the beginning of our The Hunt for the Best Humidifier best-in-class review article.

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Curious how we rate products? Take a look at our How We Test article to find out.

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