Hyv?rinen, A.
2002
Dissertation, National Public Health Institute, Department of Environmental Health, University of Kuopio, Finland
| ABSTRACT
Moisture and mold problems in buildings are known to cause health effects, but the causal agents of the exposure and the mechanisms of the health effects are obscure. To understand this phenomenon it is important to know how the indoor environment of a moisture damaged building differs from that of a normal, nondamaged building. In this thesis, the differences between moisture damaged buildings and reference buildings in indoor air pollutants, especially microbes, were studied in 38 residences, six day-care centers and two schools with several methods including microbial sampling of air, surfaces, building materials and dust, determination of volatile organic compounds, formaldehyde and house dust mites. In addition, microbial diversity and concentrations in different building materials with moisture damage were characterized. Furthermore, the associations between moisture and mold damage in building and symptoms or mold-specific IgG levels of occupants were examined. The wintertime concentrations of total viable fungi and concentrations of Penicillium, Aspergillus, and yeasts in the moisture damaged buildings were higher than in the reference buildings. Higher levels of fungi were observed especially in the particle size fraction of 2-3 um. In addition, the fungal diversity was larger in the moisture damaged buildings. Certain fungal genera, such as Stachybotrys, Ulocladium, Tritirachium and Exophiala, were detected only in the air of the moisture problem buildings. No differences were observed in the concentrations or occurrence of the other parameters: airborne viable bacteria, TVOC, formaldehyde, fungi in house dust and house dust mites The fungal concentrations in moisture damaged and reference buildings overlapped in most cases in moisture damaged and reference buildings, and hence no absolute level could be said to typically indicate the existence of moisture damage. However, by examining both the levels and flora of the air samples, indications of moisture problems can be achieved. The determination of microbial levels and flora especially in building materials, but also on surfaces, were shown to give additional information on the microbial flora in building and this knowledge can be utilized in source characteri zation. The temporal variation of the fungal concentrations was significant both in index and reference residences, whereas spatial variation affected mostly the levels in the index residence. In order to reliably ascertain the fungal level of a residence, a sampling campaign of 11 different sampling days in tw o rooms was proposed.
Fungal diversity in moisture damaged building materials was large. Stachybotrys was associated with gypsum boards. Acremonium, Aspergillus versicolor and actinobacteria were associated with ceramic materials and they occurred often together on the other materials as well. Sphaeropsidales and yeasts occurred often concurrently in damaged building materials. Mold-specific serum IgG levels were associated with only a few microbial findings. The occurrence of elevated serum levels was contradictory in exposed and non-exposed populations in different studies. It can be concluded that mold-specific serum IgG levels are not sensitive enough to indicate the current exposure in a moisture damaged home or school environment. |
