Associations of household dampness with asthma, allergies, and airway diseases among preschoolers in two cross-sectional studies in Chongqing, China: Repeated surveys in 2010 and 2019

•We conducted a cross-sectional study in 2010 and its repeated study in 2019.•Proportions of home damp indicators were significantly lower in 2019 than in 2010.•Prevalences of most studied diseases were significantly lower in 2019 than in 2010.•Damp exposures were associated with increased odds of diseases in both studies.•Most diseases exposure-responded with the cumulative numbers of damp indicators. Many studies have investigated the associations between household damp indicators, and allergies and respiratory diseases in childhood. However, the findings are rather inconsistent. In 2010, we conducted a cross-sectional study of preschoolers aged three-six years in three urban districts of Chongqing, China. In 2019, we repeated this cross-sectional study with preschoolers of the same ages and districts. Here, we selected data for 2935 and 2717 preschoolers who did not change residences since birth in the 2010 and 2019 studies, respectively. We investigated associations of household damp indicators with asthma, allergic rhinitis, pneumonia, eczema, wheeze, and rhinitis in childhood in the two studies. The proportions of residences with household damp indicators and the prevalence of the studied diseases (except for allergic rhinitis) were significantly lower in 2019 than in 2010. In the two-level (district-child) logistic regression analyses, household damp exposures that showed by different indicators were significantly associated with the increased odds of lifetime-ever asthma (range of adjusted odds ratio (AOR): 1.69–3.50 in 2019; 1.13–1.90 in 2010), allergic rhinitis (1.14–2.39; 0.67–1.61), pneumonia (1.09–1.64; 1.21–1.59), eczema (0.96–1.83; 0.99–1.56), wheeze (1.64–2.79; 1.18–1.91), rhinitis (1.43–2.71; 1.08–1.58), and current (in the past 12 months before the survey) eczema (0.46–2.08; 0.99–1.48), wheeze (0.97–2.86; 1.26–2.07) and rhinitis (1.34–2.25; 1.09–1.56) in most cases. The increased odds ratios (ORs) of most diseases had exposure–response relationships with the cumulative number (n) of household damp indicators in the current and early residences. Our results indicated household damp exposure could be a risk factor for childhood allergic and respiratory diseases, although the magnitudes of these effects could be different in different studies.