Residential exposure to mold, dampness, and indoor air pollution and risk of respiratory tract infections: a study among children ages 11 and 12 in the Danish National Birth Cohort

BackgroundThe burden of respiratory tract infections (RTIs) is high in childhood. Several residential exposures may affect relative rates.ObjectivesTo determine risk of RTIs in children ages 11 and 12 by residential exposures.MethodsWe included children in the Danish National Birth Cohort (DNBC) at ages 11 and 12. We estimated incidence risk ratios (IRR) and 95% confidence intervals (CI) for counts of RTIs within the last year by exposure to mold/dampness, gas stove usage, summer and winter candle-burning, fireplace usage, cats and dogs indoors, and farmhouse living. We also estimated IRR and 95% CI for RTIs for predicted scores of four extracted factors ('owned house', 'mold and dampness', 'candles', and 'density') from exploratory factor analyses (EFA).ResultsWe included 42 720 children with complete data. Mold/dampness was associated with all RTIs (common cold: IRRadj 1.09[1.07, 1.12]; influenza: IRRadj 1.10 [1.05, 1.15]; tonsillitis: IRRadj 1.19 [1.10, 1.28]; conjunctivitis: IRRadj 1.16 [1.02, 1.32]; and doctor-diagnosed pneumonia: IRRadj 1.05 [0.90, 1.21]), as was the EFA factor 'mold/dampness' for several outcomes. Gas stove usage was associated with conjunctivitis (IRRadj 1.25 [1.05, 1.49]) and with doctor-diagnosed pneumonia (IRRadj 1.14 [0.93, 1.39]). Candle-burning during summer, but not winter, was associated with several RTIs, for tonsillitis in a dose-dependent fashion (increasing weekly frequencies vs. none: [IRRadj 1.06 [0.98, 1.14], IRRadj 1.16 [1.04, 1.30], IRRadj 1.23 [1.06, 1.43], IRRadj 1.29 [1.00, 1.67], and IRRadj 1.41 [1.12, 1.78]).ConclusionResidential exposures, in particular to mold and dampness and to a lesser degree to indoor combustion sources, are related to the occurrence of RTIs in children.