The effects of local factors on the concentrations and flora of viable fungi in school buildings

Although insufficient dose–response data are available for the setting of any health-based criteria on bioaerosol levels, a relation has been found between indoor microbial exposure and a range of adverse health effects, such as respiratory illnesses and allergies in humans. Thus, it is important to determine all of the contributing factors related to the composition and concentration of indoor bioaerosols, including fungal levels in indoor air. The aim of this study was to review and summarize the local factors affecting concentrations of viable fungi in school environments. The material in this literature review consists of peer-reviewed journal articles found using PubMed and Google Scholar and searching the lists of references of relevant articles (based on their titles and abstracts). An analysis of the resulting data confirmed that there is strong or extremely strong scientific evidence that mold/moisture damage, the season (temperature, humidity), the type and rate of ventilation, activities of occupants, the presence of carpet, the number (or density) of occupants, and diurnal variations affect the concentration of viable fungi in the school buildings. In addition, there is scientific evidence that the age of the building, the building frame material, moisture-damage repairs, outdoor fungal concentration, sampling at different times of the day, and study location influence measured viable fungi concentrations in school buildings. This study offers valuable information that can be used in the interpretation of the fungal analysis and to decrease microbial exposure by reducing known sources and/or contributing factors. However, more studies of different local factors contributing to the human microbial exposure in school buildings—as well as other type of buildings and different indoor environments—are needed.