Improved methods for assessing and reducing the health effects of poor indoor air

In Finland, problems with indoor air quality (IAQ) are common in both residential and public buildings. The adverse health effects, especially respiratory symptoms due the moisture and mold damage have been well known for a long time. However, it is still unclear which mechanisms results in adverse health effects. Studies regarding IAQ in school buildings have typically carried out specific investigations, such as microbial measurements, and few have collected broad, simultaneous data of perceived and measured IAQ. This thesis aims to improve and develop the available methods for assessing the health-related exposures to and reported IAQ in moisture damaged residential and school buildings with and without IAQ problems and complaints. Research data are from the following four projects: HOTES (I publication of the thesis), Indoor Air Police, EURA, and TOXICPM (II-IV publications of the thesis). In HOTES, exposure assessments of fungi and bacteria (incl. actinomycetes) on health effects (reported and measured: peak expiratory flow, PEF and fractional exhaled nitric oxide, FeNO) were conducted in 41 severely moisture damaged homes. In Indoor Air Police, the exposure and health effects among the occupants of school buildings with (24 classrooms) and without (12 classrooms) IAQ problems were characterized based on a new method to collect real-time information of perceived IAQ using a developed online questionnaire. In third publication, the efficiency of improved ventilation to reduce exposure and reported perceived IAQ was tested. The fourth publication involved conducting a comprehensive characterization of IAQ in school buildings with and without reported IAQ complaints and detecting measurable differences between these buildings. This thesis showed that increased microbial growth in building structures is associated with poorer perceived health and increases in respiratory tract and general symptoms, especially among adults. The developed online questionnaire enables collecting real-time data on a large scale in schools and can be a useful extra tool as a first step in screening IAQ problems. Even relatively small changes in the airflow and pressure differences can have an effect on the measurable and perceivable parameters of IAQ. The concentration of airborne culturable fungi and the occurrence of fungal species in dust demonstrated most clearly the differences between the problem and the reference schools, especially of Trichoderma. This thesis provides novel results on tools to assess and improve IAQ, including a new questionnaire, determination of microbial growth from building materials, and use of indoor positive pressure.