We all know that keeping humidity in our home during the winter is important for our skin, throat and overall health, but did you also know that it’s vital to the health of our home? If humidity levels dip too low our furniture and house will deteriorate and certain germs will thrive. Click below the jump to find out what humidity levels you should keep in your home year round, and different techniques to do so.
Humidity Levels Are Too Low
During the winter humidity levels drop because cold air holds less moisture than warm air. Homes that utilize forced air heating have an exacerbated problem because furnaces use combustion to create hot air, thus burning out most of the water vapor that existed in the first place. To make matters worse, when humidity levels dip the ambient air feels cooler than more humid environments, and we turn up the heat to compensate.
Low humidity causes static electricity, dry skin and hair, increased susceptibility to colds and respiratory illness, and can allow viruses and germs to thrive. Wood floors, furniture and millwork will split and crack, paint will chip, and electronics can be damaged because of low humidity levels. Adding a humidifier to your home will remedy these problems; there are three standard types from which to choose:
- Evaporation: Adding moisture to the air is as simple as placing a vessel of water on top of, or next to, a radiator (or other air heating system). Leaving wet towels and clothes out to dry are other ways to introduce moisture into the air. This is a very low-tech and low power method, however the strength and humidity controls are limited, and available moisture is dependent on the size of the vessel used, and must be frequently refilled.
- Portable/Room: The most common type of humidifier is a portable one. There are two types: cool mist and warm mist, both of which use a a reservoir to hold water. The cool mist uses a wick to absorb the water and a fan blows air through a moistened filter &mdash as the air passes through the filter, it evaporates some of the water into the room. Warm mist humidifiers use a heating element that heats the water before dispersing it into the air. The pros of portable systems are that they are easy to use, a variety of styles and prices are available, and they can be moved as needed. However, similar to the evaporative method above, control and measure of relative humidity is limited, and the reservoir must be refilled about every 24 hours.
- Whole House: This is the best and most controllable humidity system. A whole house humidifier is added to a furnace and vapor is distributed directly into the heated air and circulated throughout the house via the furnace duct system. The system is the most expensive, can be installed by owner or a professional, and requires a cold water connection and room for the humidifier unit. Humidity levels are controlled via a humidistat and the method has the greatest humidification capacity and is most consistent.
Humidity Levels Are Too High
It is possible for homes to have too much humidity, which will create its own set of problems, particularly the issue of condensation. This does not typically occur in older homes, but new, tightly constructed buildings will retain more heat and moisture, which is when mechanical ventilation is important. During the winter you will first notice this at windows: when warm, moist air comes in contact with a cold window, air temperature drops and it can no longer hold the water vapor and condensation results. If a home does not have the proper mechanical and natural ventilation, excess water vapor can travel through walls and ceilings, causing wet insulation, peeling paint, and mold on walls and rot in woodwork. Try these steps to lower humidity in your home:
- Turn down or off humidifier, and use a dehumidifier when necessary – particularly in basements and during the summer.
- Use exhaust fans while cooking and bathing or open a window to exchange fresh, drier air.
- Reduce the amount of water introduced into the home by cooking with covered pots; taking cooler, shorter showers; venting clothes dryers directly to the outside; and reduce the number of plants in the home.
- In tightly constructed homes, use an energy recovery ventilator.
How to Gauge Indoor Humidity Levels:
- Fogging and condensation accumulating on windows, moisture and mold occurring on walls and ceilings is an indication of too much humidity.
- Increased instances of static electricity, dried and cracking millwork and paint indicate low humidity levels.
- Use a digital or analog hygrometer to measure humidity levels.
- If you use a whole house humidification system, use a humidistat to control and monitor humidity levels.
Ideal in-home humidity levels should hover around 45%. Anything under 30% is too dry, over 50% is too high.
(Image by Flickr member dolapo licensed for use under Creative Commons)


White Enamel Four-P...
hmm, as far as I've understood it's actually really dangerous to have a high humidity in your home as it will cause fungi to grow and many fungi are known to cause breathing problems and horrible skin reactions. There are fungi that live in our houses that can eat you alive. There have been a lot of problems with humidity during winter in our neighbourhood and a few people have been hospitalised due to fungi caused breathing and skin problems.
abbytail- yes that's true, see the section "Humidity Levels Are Too High" above. Both low and high humidity levels can cause various viruses, bugs, mold, etc to thrive, which is why it's key to have it in that 30% - 50% range, but ideally 40-45%. That's very unfortunate and strange to hear about your neighborhood, but these things will widely vary depending on your climate and region. It'd be good to get your home inspected to see if there's a hidden, or larger issue lurking. Good luck!
I cannot imagine having to add more water to my air. We run a dehumidifier year round because it's so damp where we live. We have to - we had an environmentalist do some testing, and our condo is inadequately ventilated, and there is nothing else we can do about it. (we cannot make structural changes to our dwelling, and I can tell you the HOA won't either...)
What germs thrive in low humidity?? I thought germs loved warm and moist.
Just like plants, some germs like a dry environment; some need more moisture.
I've lived in some very dry places and can testify that a humidifier makes a huge difference to the number of colds and coughs we get. Also, it cuts the static electricity. So much nicer not being shocked by everything you touch.
ohjodi - That's true, but our mucous membranes like it a bit moist as well. In an environment with too low humidity, these are damaged or just don't work as well as they should, making them ideal ports of entry for pathogens.
I live in a very hot apartment that is thankfully fairly dry. I bring moisture by air drying my laundry, very green, and leaving my bathroom doors open after a shower. It has been enough so far.
If you are worried about germs, you had better keep the water in your humidifier clean. Scrub out the water container regularly. There are some nasty things that grow in stale water and the humidifier sends them airborn. There are also additives you can buy to kill these germs.
If you're allergic to dust mite scat like me you should keep your relative indoor humidity at 40% or lower. High humidity = more dustmites! Living in Virginia it's hard to keep it that dry in the sweltering summers but in the winter it's been pretty easy to keep it around 40% and I've had no allergy issues.
This is a pretty helpful article, but I am pretty sure the correct word to use would be "exacerbated" not "exasperated". Pretty sure forced heat isn't irritating the problem.
you should also mention that it's best to use distilled water in the humidifier, especially if you have an ultrasonic model.