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.

Abstract

Background: The burden of respiratory tract infections (RTIs) is high in childhood. Several residential exposures may affect relative rates.

Objectives: To determine risk of RTIs in children ages 11 and 12 by residential exposures.

Methods: We 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).

Results: We included 42 720 children with complete data. Mold/dampness was associated with all RTIs (common cold: IRR_adj 1.09[1.07, 1.12]; influenza: IRR_adj 1.10 [1.05, 1.15]; tonsillitis: IRR_adj 1.19 [1.10, 1.28]; conjunctivitis: IRR_adj 1.16 [1.02, 1.32]; and doctor-diagnosed pneumonia: IRR_adj 1.05 [0.90, 1.21]), as was the EFA factor 'mold/dampness' for several outcomes. Gas stove usage was associated with conjunctivitis (IRR_adj 1.25 [1.05, 1.49]) and with doctor-diagnosed pneumonia (IRR_adj 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: [IRR_adj 1.06 [0.98, 1.14], IRR_adj 1.16 [1.04, 1.30], IRR_adj 1.23 [1.06, 1.43], IRR_adj 1.29 [1.00, 1.67], and IRR_adj 1.41 [1.12, 1.78]).

Conclusion: Residential 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.