| Thirty-nine houses with high levels of biologically active contaminants in Wallaceburg, Canada, and twenty houses with low levels of biologically active contaminants, were subjected to field inspections and testing, monitoring of indoor environmental condi-tions, and simulation to predict the condensation formation potential in winter Occupant health was evaluated through ques-tionnaires and blood sampling from an index child (closest to age ten)for analyses of T-lymphocyte and B-lymphocyte structure. We found that low air leakage and natural ventilation were not associated with higher measures of mold growth. Analyses found that moisture sources in the houses were a more significant factor in mold and dust mite antigen levels than relative humidity. Visible mold area was not a good predictor of ergosterol concentrations, indicating that hidden mold growth may be a factor
This paper addresses the influence of house and construction characteristics on the levels of mold growth and the building science lessons provided by this project.
"There is a considerable body of evidence that indoor biological agents such as mold (fungi), dust mites, and bacterial endotoxins are associated with adverse health effects, as well as the degradation of the building and its contents and unpleasant appearance and odors. Some species of fungi produce potent mycotoxins and allergens. Clinically recognized diseases caused by fungi include cancer, infection, hypersensitivity pneumonitis, and allergic bronchopilmanary aspergillosis. Apart from these clinically recognized diseases, the reported presence of visible mold in houses has been consistently associated with increased symptoms, if not objec-tive measures, of health (Yeung et al. 1995; Murray and Ferguson 1983; Owen et al. 1990; Wickman et al. 1991 Flan-nigan et al. 199 1; Tobin et al. 1987)."
Characteristics of a Mold Resistant House
Designing and constructing a house for mold resistance would incorporate the following concepts.
? There should be a well-drained foundation with base-ment floors and walls that are protected from hydro! static pressure and capillary transfer of moisture.
? The sump pit, if required, should be sealed from the inside space.
? All walls and ceiling, including the basement, should b~ evenly provided with a continuous air barrier system to keep indoor air from moving out to cold surfaces (a location inside the insulation is preferable) and a vapor-. resistant layer on the wann side of the insulation. Atten-- 1 tion should be paid to eliminating thermal bridges, but -- I the most important thing, and the most difficult, is the, resistance to air leakage
? Windows should be selected for condensation resistance and water leakage resistance. They should be mounted in a manner that maintains airtightness with the wall air bar-rier system and encourages circulation of indoor air over the inside surfaces (no deep window wells). The material used for sills should be nonabsorbent
? A ventilation system that serves all rooms in the build-ing should be provided.
? There should be air circulation within rooms, either by the heating system or with other fans.
? Exhaust should be supplied to high vapor production rooms, and it should be used.
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