METHODS: We collected classroom dust from 24 junior high schools in three geographically distanced areas in Malaysia (Johor Bahru, Terengganu and Penang), and conducted culture-independent high-throughput microbiome and untargeted metabolomics/chemical profiling.
RESULTS: 1290 students were surveyed for asthma symptoms (wheeze). In each centre, we found significant variation in the prevalence of wheeze among schools, which could be explained by personal characteristics and air pollutants. Large-scale microbial variations were observed between the three centres; the potential protective bacteria were mainly from phyla Actinobacteria in Johor Bahru, Cyanobacteria in Terengganu and Proteobacteria in Penang. In total, 2633 metabolites and chemicals were characterised. Many metabolites were enriched in low-wheeze schools, including plant secondary metabolites flavonoids/isoflavonoids (isoliquiritigenin, formononetin, astragalin), indole and derivatives (indole, serotonin, 1H-indole-3-carboxaldehyde), and others (biotin, chavicol). A neural network analysis showed that the indole derivatives were co-occurring with the potential protective microbial taxa, including Actinomycetospora, Fischerella and Truepera, suggesting these microorganisms may pose health effects by releasing indole metabolites. A few synthetic chemicals were enriched in high-wheeze schools, including pesticides (2(3H)-benzothiazolethione), fragrances (2-aminobenzoic acid, isovaleric acid), detergents and plastics (phthalic acid), and industrial materials (4,4-sulfonyldiphenol).
CONCLUSIONS: This is the first association study between high-throughput indoor chemical profiling and asthma symptoms. The consistent results from the three centres indicate that indoor metabolites/chemicals could be a better indicator than the indoor microbiome for environmental and health assessments, providing new insights for asthma prediction, prevention and control.
METHODS: A school environment study was performed among randomly selected students in eight randomly selected secondary schools in Penang, Malaysia. Information on eye symptoms and demographic data was collected by a standardised questionnaire. BUT was measured by two methods, self-reported BUT (SBUT) and by the non-invasive Tearscope (NIBUT). Dust was collected by vacuuming in 32 classrooms and analysed for five fungal DNA sequences. Geometric mean (GM) for total fungal DNA was 7.31*104 target copies per gram dust and for Aspergillus/Penicillium DNA 3.34*104 target copies per gram dust. Linear mixed models and 3-level multiple logistic regression were applied adjusting for demographic factors.
RESULTS: A total of 368 students (58%) participated and 17.4% reported weekly eye symptoms the last 3 months. The median SBUT and TBUT were 15 and 12s, respectively. Students wearing glasses (OR 2.41, p=0.01) and with a history of atopy (OR=2.67; p=0.008) had more eye symptoms. Girls had less eye symptoms than boys (OR=0.34; p=0.006) Indoor carbon dioxide in the classrooms was low (range 380-720ppm), temperature was 25-30°C and relative air humidity 70-88%. Total fungal DNA in vacuumed dust was associated with shorter SBUT (4s shorter per 105 target copies per gram dust; p=0.04) and NIBUT (4s shorter per 105 target copies per gram dust; p<0.001). Aspergillus/Penicillium DNA was associated with shorter NIBUT (5s shorter per 105 target copies per gram dust; p=0.01).
CONCLUSION: Fungal contamination in schools in a tropical country can be a risk factor for impaired tear film stability among students.