NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
September 28, 2000
Do you have watery eyes, a sore throat, wheezing and more asthma attacks? These cold-like symptoms may be caused by mold rather than a cold, says Ken Hellevang, North Dakota State University Extension engineer.
"Exposure to high mold spore levels can lead to an allergy to mold," Hellevang says. "The symptoms may occur as it gets colder outside. During the summer, allergens are diluted by ventilation with house windows open, but the concentration of allergens from mold in the home is greater when the windows are closed."
Due to continued wet soil conditions and damp building materials, moisture and mold problems are expected to continue this fall, Hellevang says. Studs, drywall and other building materials that got wet due to flooding may still be wet and will be mold infested if the areas were not opened to permit adequate drying.
Basement humidity problems will continue if the soil is wet because moisture vapor moves into the house through concrete basement walls.
"Where there is excess moisture, there is almost always mold," Hellevang says. "If you can see or smell mold, try to eliminate the excess moisture and remove the mold. Most porous mold-contaminated materials should be discarded because it is difficult to remove the mold from within the porous surface. Even if the mold is not growing, it still can cause health problems as an allergen even when it is dry."
Non-porous materials should be cleaned with hot water and detergent followed by an application of disinfectant solution, such as diluted household bleach. The moisture problem must be eliminated to prevent future mold growth. Treating existing mold will not prevent future mold growth.
Hellevang says because moisture condenses on cool surfaces, condensation problems are expected as outdoor temperatures cool. With an indoor relative humidity of 60 percent and a room temperature of 70 F, condensation will occur on double-glazed windows when the outside temperature is below about 34 F.
"Reduce condensation problems by lowering indoor air relative humidity by ventilating with dry, cool outside air. Exchange the damp indoor air with drier outside air."
Indoor relative humidity should be less than about 60 percent during the summer and between about 30 percent and 40 percent during the winter.
Hellevang says humidity meters purchased at hardware or discount stores need to be calibrated for accuracy since the meters may be off by 20 percent or more. Place the meter in a 5-quart plastic sealed bag with a cup containing 1/2 cup table salt and 1/4 cup water. The meter should read about 75 percent relative humidity after at least 12 hours at normal room temperature. Electronic relative humidity meters tend to be more accurate than mechanical meters.
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Source: Ken Hellevang, (701) 231-7243, kjh-eng@ndsuext.nodak.edu
Editor: Becky Koch, (701) 231-7875, bkoch@ndsuext.nodak.edu