Association of indoor air quality and preschool children's respiratory symptoms.

BACKGROUND This study aimed to assess the association between exposure to indoor air pollution in DCCs (Child Day Care Centers) and the respiratory symptoms of children under 6 years old. METHODS Air quality data were collected three times regarding to seasonal variation. Pollutants measured in 11 DCCs included PM₁₀, CO, NO₂, SO₂, O₃, benzene, bacteria, fungi, and dust mite. The frequencyof respiratory symptoms including coughing, rhinitis, and dyspnea were recorded via teacher and parent-report questionnaires. Fractional exhaled nitric oxide (FENO) levels were measured to assess airway inflammation. RESULTS 436 children participated in the study. 83% completed data collection in all 3 seasons. The frequency of rhinitis correlated with PM₁₀ (IRR=70.3, 95%CI=12.4-399.7, p<0.001), CO (IRR=3.2, 95%CI=2.4-4.2, p<0.001), benzene (IRR=2.3, 95%CI=1.8-3.2, p<0.001) and D.Pteronyssinus level (IRR=2.1, 95%CI=1.7-2.7, p<0.001). The frequency of coughingcorrelated with levels of PM10 (IRR=15.2, 95%CI=3.0-78.2, p<0.001), CO (IRR=2.8, 95%CI=2.1-3.7, p<0.001), benzene (IRR=1.4, 95%CI=1.1-1.9, p=0.02). The frequency of dyspnea correlated with D.Pteronyssinus level (IRR=3.9, 95%CI=1.7-9.1, p=0.001). FENO levels associated with high benzene levels (OR=5.9, 95%CI=1.5-22.9, p=0.01). The majority of DCCs had at least one PM₁₀ measurement above the standard level, and these high levels were noted in all 3 seasons. Three DCCs had PM₁₀ levels above the standard level in all seasons. 64% of the DCCs had indoor bacterial counts above the standard level in all seasons. CONCLUSIONS PM₁₀ and bacterial count is a significant problem in Bangkok metropolitan DCCs. The respiratory symptoms of children positively associated with PM₁₀, CO, benzene and dust mite levels.