Keeping a Healthy Home
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Humidity Control
"A number of factors allow biological agents
to grow and be released into the air. Especially important is
high relative humidity, which encourages house dust mite populations
to increase and allows fungal growth on damp surfaces."
—Indoor Air
Pollution: An Introduction for Health Professionals
Too much moisture in a home can lead to mold, mildew, and
other biological growth. This in turn can lead to a variety
of health effects ranging from more common allergic reactions,
to asthma attacks, and hypersensitivity pneumonitits, for example.
In addition to health problems, high relative humidity or water
that enters building cavities that is not allowed to dry quickly
can lead to problems such as rot, structural damage, and premature
paint failure.
—EPA: Remodeling
Your Home? Controlling Moisture
Humidity Control
If the indoor environment is to be controlled,
then the humidity
levels must be maintained as well. This, however, does not
mean that more dehumidification is better. The optimum range
of relative
humidity in an indoor environment is between 40% and 50%. Above
50%, an environment will grow mold and have more problems with
dust mites. Below 40%, bacteria will begin to thrive.
The tissue in our body is composed mostly of water. When humidity
levels are low, moisture is pulled out of our tissues and released
into the environment. This is a normal process of evaporation.
If the body loses too much water, the tissues dry up. The skin's
elasticity goes, and with it, function declines. Besides dry
skin, the symptoms of dehydration include chronic joint and
muscle pain, raspy throat, sore eyes and lack of mental concentration.
Low humidity levels can also cause or aggravate respiratory
ailments.
Environments with humidity levels above 50% allow mold, dust
mites, bacteria and viruses to thrive. High humidity also
increases the rate at which VOC's are released into the air.
Mold is considered by the EPA to be the "greatest threat
to the
indoor environment".
Dust mites are the most common allergen-producing organism
found in the home. They are members of the arachnid (spider)
family.
In order to get water, dust mites must absorb moisture
from the air. With humidity levels controlled between 40%
and
50%, dust
mites can not absorb enough water and die.
Humidity control, though, is only a part
of the solution. For a complete solution to indoor air quality,
you
will need
to have
good ventilation, air filtration, and protect the building
envelope itself.
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