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Moisture damage can influence the subjective assessment of indoor air quality (subjective IAQ) in various ways. We studied whether the frequency of symptoms reported across students at school level mediates the relationship between observed mold and dampness in a school building and students' subjective IAQ. To answer this research question, we tested a multilevel path model. The analyzed data were created by merging two nationwide data sets: (a) survey data from students, including information on subjective IAQ (N = 24,786 students); (b) data from schools, including information on mold and dampness in a school building (N = 222). After the background variables were adjusted, schools' observed mold and dampness were directly and significantly related to poor subjective IAQ (standardized beta (β)= 0.22, P =.002). In addition, in schools with mold and dampness, students reported significantly more symptoms (β = 0.22, P =.023) than in schools without; the higher the prevalence of symptoms at school level, the worse the students' subjective IAQ (β = 0.60, P <.001). This indirect path was significant (P =.023). In total, schools' observed mold and dampness and student‐reported symptoms explained 52% of the between‐school variance in subjective IAQ. [ABSTRACT FROM AUTHOR]

Exposure to moisture‐damaged indoor environments is associated with adverse respiratory health effects, but responsible factors remain unidentified. In order to explore possible mechanisms behind these effects, the oxidative capacity and hemolytic activity of settled dust samples (n = 25) collected from moisture‐damaged and non‐damaged schools in Spain, the Netherlands, and Finland were evaluated and matched against the microbial content of the sample. Oxidative capacity was determined with plasmid scission assay and hemolytic activity by assessing the damage to isolated human red blood cells. The microbial content of the samples was measured with quantitative PCR assays for selected microbial groups and by analyzing the cell wall markers ergosterol, muramic acid, endotoxins, and glucans. The moisture observations in the schools were associated with some of the microbial components in the dust, and microbial determinants grouped together increased the oxidative capacity. Oxidative capacity was also affected by particle concentration and country of origin. Two out of 14 studied dust samples from moisture‐damaged schools demonstrated some hemolytic activity. The results indicate that the microbial component connected with moisture damage is associated with increased oxidative stress and that hemolysis should be studied further as one possible mechanism contributing to the adverse health effects of moisture‐damaged buildings. [ABSTRACT FROM AUTHOR]