(You can also read our Humidifier FAQ for frequently asked questions about humidifiers). 

Room air humidifiers help to improve air quality and alleviate symptoms of dry air, such as sinus headaches, dry skin, sneezing and coughing. During the dry winter months, when forced air heating systems can severely dry out the air, humidifiers are an excellent way for you to add back essential moisture into the air. Dry air is often the source of many ailments, such as dry skin, itchy eyes, and cracked lips. It affects everyone equally, regardless of allergies or asthma. It can even damage wood furniture, causing it to crack. Low humidity levels in your air can also dry out the mucous lining inside your nose and throat, causing sore scratchy throats, nose bleeds, and sinus infections. Adding a room air humidifier to your nursery can help your baby sleep comfortably at night, and is also a great way to help prevent colds and the spread of germs during the flu season.

Humidity Levels:

The optimal humidity level for overall healthy air ranges from between 25% to 55% relative humidity. An inexpensive humidity/temperature gauge (hygrometer) allows you to easily monitor the relative humidity level in your room. While low humidity levels below 25% are unhealthy, you also want to make sure not to have too much moisture in the air. Room air humidity levels higher than 55% can actually encourage the growth of mold, bacteria, fungi and dust mites. You can often tell if you have too much humidity by looking at your windows. Condensation buildup on windows is a telltale sign of too much humidification. Most humidifiers have built-in humidistats which you can adjust to your liking, thereby varying the amount of humidity you add to the room. More expensive models also have hygrometers built-in, with readouts or gauges telling you the humidity level in the room, and allowing you to specify the exact level of humidity you prefer.

Types of Humidifiers:

There are many different types of humidifiers from which to choose. They vary in both size (or gallon output per day), and method of humidification (cool mist, evaporative, warm mist, and ultrasonic). The largest sizes of humidifiers are called console humidifiers, which are capable of humidifying multiple rooms and very large areas. Room humidifiers are smaller units better suited to single small, medium or large sized room in your home and office. Here is a brief overview of the different types of humidifiers:


Cool Mist Evaporative Humidifiers
The most common type of humidifier, a cool mist evaporative humidifier adds moisture into the air using the principles of natural evaporation, which is the cleanest method of humidification. A wick filter (sometimes also called a wicking filter) sits in the base of the humidifier and absorbs water. A fan then blows dry room air through the saturated wick filter, causing the water in the filter to evaporate into the room, thereby adding moisture into the air. The wick filter also traps any impurities, such as minerals, that may be present in the water, ensuring that the moisturized air is completely pure, clean, and free of any minerals or impurities. Most wick filters should be replaced approximately every 2 months, although some models have cleanable, reusable wick filters. 
Pros: Cons:
Wick filter ensures a pure and clean mineral-free moisture output.
Very low power consumption.
Fans can be powerful enough to cover large areas with a single humidifier.
Fans make more noise than other types of humidifiers (noise level depends on fan speed).
Most wick filters need to be replaced approximately every 2 months.
Bacteria and mold can grow on wick filter (may be reduced by using a bacteria treatment water additive).

Warm Mist Humidifiers
Warm mist humidifiers use a heating element to boil the water in the humidifier and release it into the air in the form of a warm steam. If you live in a cold climate, using a warm mist humidifier will help make the room feel warmer than it actually is (as opposed to a cool mist humidifier, which can have the opposite effect). Warm mist steam humidifiers are quieter than cool mist evaporative humidifiers, because they do not use a fan. Instead, the heating element simply boils the water into a pure steam, which rises into the air free of all minerals and impurities. Any mineral content that was present in the water is left behind in the humidifier, and will not enter the room air. Mineral deposits left behind in the humidifier can be removed using vinegar. Some models also use optional mineral absorption pads, which help to absorb the mineral deposits before they can stick to the humidifier. 

Pros: Cons:
Quiet operation.
No wick filters to replace.
Pure, clean mineral-free moisture output.
Some models have a medicine cup to disperse soothing vapors into the room.
Higher power consumption (heating element uses more electricity than other humidifiers).
Most units are limited to small rooms only.
May pose a burn risk for small children if the humidifier is accidentally tipped over.

Ultrasonic Humidifiers (cool or warm mist)
Ultrasonic humidifiers are the quietest humidifiers around. They are so quiet, they are often described as being nearly silent. An ultrasonic humidifier uses the power of high frequency sound waves to vibrate a metal diaphragm at an "ultrasonic" frequency, thereby breaking the water in the humidifier down into an ultra-fine vapor mist. This vapor mist, which looks like a fog, is released into the air using a very small and quiet fan. Any minerals or impurities that are present in the water are released into the air with the mist. Many ultrasonic humidifiers use demineralization cartridges, which serve to trap these minerals before they are released into the air, although the demineralization cartridges are usually not 100% effective. You may want to use distilled water if you experience a problem with "white dust" settling on surfaces near the humidifier. Some ultrasonic humidifiers have a heating option as well, which heats up the water before releasing it into the air. This helps eliminate bacteria growth in the water, and also keeps the room from feeling too cold. 

Pros: Cons:
Ultra quiet, near silent operation.
No wick filters to replace.
Low power consumption (when using cool mist).
Unless using distilled water, impurities can sometimes enter the air in the form of "white dust" (this can sometimes be controlled with a replaceable demineralization cartridge).
Most units are limited to small rooms only.



In addition to the above types of humidifiers, here are some additional unique humidifier features to consider:


Front Fill or Top-Fill Humidifiers (Direct Pour-In)
While most humidifiers use removable water tanks or bottles that are carried to and filled at a sink or bathtub, there are a few models which bypass the tank entirely and allow you to pour water directly into the humidifier using your own water container. With these easy pour-in humidifiers, you can even use a small cup if you have difficulty lifting or carrying heavy water bottles. This feature may be critical for those with arthritis or any difficulty lifting or carrying. 

Pros: Cons:
No heavy water bottles to lift, turn upside down, carry, or break.
Quieter than other humidifiers - no "gurgling" noise sometimes heard as water empties from tanks.
Easy to clean.
You provide your own water container (such as a pitcher or cup).
More standing water inside humidifier increases the potential for mold growth.

Whole House Console Humidifiers

Based on recent scientific research, scientists recommend using a humidifier to reduce the threat of spreading the flu virus. Residential humidification experts emphasize consistent humidity levels be maintained in every room of the home or office to provide sufficient protection from the flu virus. Since single-room humidifiers are not designed to sustain humidity levels of an entire residence, consumers are encouraged to use whole-house evaporative humidifiers to provide an easy and energy-efficient solution to maintaining safe and healthy humidity levels year-round. "Whole House" humidifiers are larger units capable of producing between 8-14 gallons of moisture output per day, and can be placed near a central cold air return duct for distribution of moisture throughout the house. Whole House humidifiers (also referred to as "console" humidifiers) use natural evaporative humidification to eliminate any possible white dust emission or any other impurities from entering the room air. This is the most natural and safest form of humidification, and the only type capable of covering larger areas. 

Pros: Cons:
High output covers large or very dry areas.
Longer run time between refills means less maintenance.
Easy to clean.
Large powerful fans can be louder on high speed settings.
Evaporative wick filters need bacteria treatment additive to prevent mold growth.