Indoor air quality and respiratory health effects in school children: The HITEA study

A good air quality of the indoor environment is essential for human health; on average people spend more than 80% of their time indoors. The composition of indoor air is extremely complex and the quality can be influenced by several outdoor and indoor sources. In this thesis the effects of indoor air quality on respiratory health in primary school children has been studied. The thesis focuses on two different categories of exposure which are regularly debated in the literature in relation to respiratory health of children: dampness and microbial exposures in schools and exposure to chlorine compounds related to swimming. This thesis was completed in the framework of the HITEA project (‘Health Effects of Indoor Pollutants: Integrating microbial, toxicological and epidemiological approaches’) which investigates health effects of dampness-related indoor air pollutants, in both European homes and schools. This thesis focuses on the school arm of HITEA. Exposure to microbial and toxicological agents in elementary schools was investigated in three regions in Europe with different climates: Spain, Finland and the Netherlands. Schools with (index) and without (reference) dampness and/or mould were selected based on building questionnaires and on-site inspections. Eventually 15 index and 10 reference schools across three countries were selected for exposure and health assessment. Questionnaire information on health symptoms was collected from 9271 pupils aged 6-12. In addition lung functions were available from 2736 children. In parallel with the health measurements, environmental measurements were performed for characterization of microbial (endotoxin, β(1,3)-glucans, fungi, microbial species defined by qPCR) and other indoor exposures related to ventilation and traffic. The second aim was to study how swimming in indoor swimming pools can affect respiratory health of 6-12 year old children. Therefore, we measured trichloramine levels in swimming facilities and explored the associations with respiratory health in primary school children in the Dutch part of the HITEA study. Respiratory health and pool attendance information was collected from 2359 children in the Netherlands. Serum from 419 children was tested for allergen sensitization and CC16 levels. Our results indicate that microbial exposure can be high in classrooms, but microbial levels measured in the HITEA study did not clearly explain the found associations between school dampness and respiratory symptoms in pupils. Associations between moisture, microbial exposure and health may vary between regions and countries. Measured trichloramine levels were comparable with other studies but lower than in an earlier Dutch study. Swimming pool attendance was not associated with respiratory symptoms. The association between sensitization and swimming during the first two years of life suggests that early-life exposures might be important, although needs further study. The interpretation of transient and chronic changes of CC16 and other inflammatory markers in relation to the pool environment and health impacts warrants further investigation. Detailed comparisons with other studies are limited as few studies have measured trichloramine levels in relation to respiratory health of children