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Straight Facts About Humidity

Humidity is the amount of moisture or water vapour in the air. You, your family, and your pets produce moisture when you breathe or perspire. Even your indoor plants produce moisture. We add water vapour to indoor air through routine household activities: cooking, showering, bathing, doing laundry, and dishwashing. And more moisture can enter your home from the surrounding soil through a basement or crawlspace.

When Is Humidity a Problem?

We need humidity for our comfort and health. But too much or too little humidity can produce a host of difficulties for householders. Some of the problems are no more than nuisances; others could be far more serious. Many are familiar to Canadians, often occurring during the heating season when it is very cold outside, our windows are closed, and indoor air circulation and ventilation are reduced.

Too Much Humidity Typically Causes:

  • Condensation on windows
  • Chapped skin and lips
  • Wet stains on walls and ceilings
  • Moldy bathroom
  • Musty smells
  • Allergic reactions
  • Long-term effects include: Damage to the house and contents

Too Little Humidity Typically Causes:

  • Scratchy nose and throat
  • Breathing problems
  • Static and sparks
  • Problems with electronic equipment
  • Damage to furniture and other items.

Diagnosing the Humidity Problem

Instead of guessing whether or not you have a humidity problem inside your house, why not find out for sure? A small, inexpensive and easy-to-use instrument called a hygrometer (sometimes referred to as a humidity sensor or a relative humidity indicator) can measure the humidity level in your house and confirm whether the house has too much or too little humidity. Once you know for sure, you can decide whether any action is required and, if so, what to do.

So You Want To Buy a Hygrometer?

The two types of hygrometers that are most suitable for household use are mechanical hygrometers and electronic hygrometers. For most households. either type will perform satisfactorily if properly used and calibrated. Hardware stores, department stores, building supply stores, and electronics stores often carry hygrometers. In fact, hygrometers are usually sold wherever you would buy a room thermometer. Hygrometers and room thermometers are often combined into a single piece of equipment.

Humidity: How Much Is Too Much, Or Too Little?

Experts have developed rules of thumb to help homeowners make decisions regarding humidity levels in their houses. The limits should be used as guides only. Acceptable or comfortable humidity levels will actually vary from season to season, from house to house, and even between rooms in the same house.

Taking Action

Humidity can be controlled. If the relative humidity in your home is too high, you can reduce it; if it is too low, you can increase it. This may require simple changes in your family’s habits, such as remembering to open or close doors or windows. Or you may need to install equipment, such as exhaust fans in bathrooms or kitchens, to remove excess humidity. Very low indoor RH levels in winter may be due to cold, dry air leaking in from outside. Sealing up the house by weather-stripping and caulking will improve humidity conditions indoors, and may reduce your heating bills at the same time. Humidifiers – both stand-alone appliances and devices attached to your furnace – can be useful for increasing indoor RH levels. But remember that humidifiers, if not installed, used and maintained properly, can also be sources of excessive moisture and mold in your home.

The final analysis

Humidity levels in your home can be too high or too low. In either case, problems can result. A hygrometer can provide the information you need to determine whether you have a humidity problem — but it must be accurate to be useful. If you have a humidity problem, it can usually be controlled.