Choosing a humidifier

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Choosing a humidifier

There are many claimed benefits to humidifying your home.

Benefits include;

Better breathing  (prevents nasal passages and lung membranes from drying out)
Longer life from wood in the home (prevents it from shrinking)
Making it feel warmer that it is (saving on heating)
Decrease in static electricity
Better skin (more elastic)
Better hair (less brittle)

There are also potential problems to humidifying your home, especially over humidifying.

Problems include;

In extremes humidity can cause wallpaper to peel and make vinyl and polished wood floor slippery,
Also overly damp furniture and walls can become a breeding ground for bacteria so get the balance right.



There are many brands of humidifier on the market but there are two main types of humidifier. Ultrasonic based and steam based.

AKA warm mist

A steam based humidifier uses a heating element to boil water and turn it into steam. The steam rises and humidifies the air. In many ways it's a bit like a kettle.


  1. The main benefit is that the steam rises in to the air and creates a greater spread of humidity.  Especially useful if you have the flu.
  2. Another benefit of the steam humidifier is that heating kills off bacteria so the air you're breathing in is far more likely to be free of harmful bacteria.
  3. Steam humidifiers also have a heating effect on the room which is good in winter.


  1. One downside is that they are noisy, there is a bubbling sound of gently boiling water which you may or may not like.
  2. Another downside is that they can be a burns hazard for overly curious or clumsy people. So they may not be advisable in kids rooms or busy corridors where they are likely to be knocked over - Especially at night. A lot of manufacturers are aware of this hazard and have built in  night lights and safety cut out features but check first and educate the young about the potential dangers of steam.
    Steam humidifiers heating effect on the room is less good in summer.


AKA cool mist

The other main type of humidifier is an ultrasonic humidifier.  An ultrasonic humidifier creates water droplets using  ultrasound waves generated by a metal diaphragm vibrating at ultrasonic frequencies (very sophisticated ).


  1. It is more quiet, producing a quiet background hum as opposed to a background sound of boiling water.
  2. The mist it produces is cool , it feels like a very fine spray as opposed to steam.
  3. It is also physically safer in situations it might get knocked over.


  1. The mist seems to just fall to the ground like spray from a spray bottle would. It output doesn't rise into the air as well as a steam humidifier.
  2. The other downside is a problem of bacteria and other micro organisms. It is claimed* that the ultrasonic humidifiers will not kill bacteria and will make some of these air bourne - potentially causing lung infections. I strongly recommend reading the following article before purchasing an ultrasonic humidifier.
    *source. U.S. Environmental Protection Agency



Ultrasonic humidifiers are more expensive that steam humidifiers, about twice the price at retail.  But ultrasonic humidifiers have slightly lower like for like running costs. (Ultrasound using less electricity than heat.)

Both types have few if any moving parts so they should last for a number of years.



So to sum up steam humidifiers;

  • Hotter and slightly noisier considered and a potentially burns especially at night.  But with a good spread and rise of humidity. Think glorified kettle

And to sum up ultrasonic humidifiers;

  • Cool, quiet, a slight lack of humidity and the potential risk of spreading bacteria if not kept hygienically clean. Think glorified spray bottle.




Theres no clear cut choice. I bought a steam humidifier and noticed a big improvement in my breathing, skin and hair however it was a bit warm and you could hear the water bubbling away. I decided that the ultrasonic humidifiers were more expensive so must be better. I bought one and found it a disappointment. It failed to properly humidify. No matter how high I put the machine ( on top of wardrobes or bookshelves ) the mist just fell to the floor.  It didn't really humidify the air as thoroughly as the steam humidifier could. 

Personally even if they were equal in cost I would still go for the steam humidifier.


Here are two good sites well worth a quick read

"U.S. Environmental Protection Agency" the source on bacteria in ultrasonic humidifiers
"Indoor Air Facts No. 8:  Use and Care of Home Humidifiers"

Office of Radiation and Indoor Air (6609J)
Office of Research and Development (MD-56)
February 1991
"How Stuff Works" overview all types of humidifiers

On the two less common humidifiers.

There are another two less common types impeller and wick or evaporative system.

The impeller uses physical force (spinning disc usually) to push water through a comb like diffuser to create a water vapour.
The evaporator system uses a fan to pass air over a moistened "wick". The air from the fan evaporates the water in the wick and thus humidifies the room.

I have not seem either of these two types offered for sale in the UK. The two types you are probably going to be choosing from are steam and ultrasonic humidifiers.



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