Total viable molds and fungal DNA in classrooms and association with respiratory health and pulmonary function of European schoolchildren

Indoor molds are associated with adverse respiratory effects in children. Although schools are important exposure sources of molds, objective measurements were more often taken in homes. Our aim was to assess indoor molds in schools and related effects on schoolchildren health. The Health Effects of the School Environment study (HESE) included 21 schools (46 classrooms) in Italy, Denmark, Sweden, Norway, and France and 654 schoolchildren (mean age 10 yr). Information on schoolchildren was collected by standardized questionnaires. Measurements of total viable molds (VM, colony-forming units, cfu/m3) and total/specific fungal DNA (cell equivalents, CE/g dust) were taken inside all classrooms in the cold season during normal activities, using the same standardized methodology. Pulmonary function tests were performed on 244 pupils. VM (mean, 320 cfu/m3) and total fungal DNA (geometric mean, 2.2 × 105 ± 2.1 CE/g dust) were detectable in all classrooms. The levels were significantly higher in buildings with mold/dampness problems. VM, but not fungal DNA, were inversely related to ventilation rate. VM exceeded the maximum standard of 300 cfu/m3 in 33% of the classrooms. In the past 12 months, dry cough at night (34%) and rhinitis (32%) were the mostly reported. Children exposed to VM levels ≥300 cfu/m3, compared with those exposed to lower levels, showed higher risk for past year dry cough at night (odds ratio, OR: 3.10, 95% confidence interval, CI: 1.61–5.98) and rhinitis (OR: 2.86, 95% CI: 1.65–4.95), as well as for persistent cough (OR: 3.79, 95% CI: 2.40–5.60). Aspergillus/Penicillium DNA was significantly positively associated with wheeze, and Aspergillus versicolor DNA with wheeze, rhinitis, and cough. There were significant inverse associations of Aspergillus versicolor DNA with forced vitality capacity (FVC) and Streptomyces DNA with both FEV1 and FVC. In conclusion, indoor VM and fungal DNA were commonly found in monitored European schools and adversely related to respiratory health. Schools should be routinely tested through both culturable and non-culturable methods for global indoor molds’ evaluation.