Associations of household renovation materials and periods with childhood asthma, in China: A retrospective cohort study

Background: Childhood asthma is prevalent in China. However, there is a lack of evidence on whether household renovation, including the materials used and the periods, are associated with the disease. Objectives: To investigate the associations between household decoration materials and renovation periods, and childhood asthma and its related symptoms. Methods: During 2010-2012, a retrospective cohort study was initiated in seven cities of China, and 40,010 children, aged 3-6 years, were recruited. Data on demographics, health status, and home decoration conditions were collected using a parent-administered questionnaire. Two-level (city-child) logistic regression analyses with adjusted odds ratios (AORs) and 95% confidence intervals (CIs) were performed to show the target associations. Sensitivity analysis was performed by stratifying data for children in the southern and northern cities. Results: Children whose homes underwent renovation or the addition of new furniture within 1 year before pregnancy, during pregnancy, at age 0-1 year, and after age 1 year had significantly (p < 0.05) higher prevalence of childhood asthma and its related symptoms. The use of solid wood floors and wallpaper had significant associations (cement: AOR, 95% CI: 1.59, 1.17-2.17; lime: AOR, 95% CI: 1.31, 1.00-1.71) with an increased risk of lifetime asthma. Household renovation and the addition of new furniture during pregnancy had significant associations with lifetime asthma (renovation: AOR, 95% CI: 1.23, 1.01-1.51); lifetime wheeze (renovation: AOR, 95% CI: 1.21, 1.05-1.39; furniture: AOR, 95% CI: 1.24, 1.14-1.36), current wheeze (renovation: AOR, 95% CI, 1.21 1.05-1.40; furniture: AOR, 95% CI: 1.23, 1.12-1.34), and current dry cough (renovation: AOR, 95% CI: 1.41, 1.23-1.63; furniture: AOR, 95% CI: 1.28, 1.17-1.41). Similar associations were found between the addition of new furniture during early childhood and lifetime asthma and its related symptoms. Except for the association between lifetime wheeze and flooring materials, the studied associations were generally stronger among children from the northern cities. Conclusions: We confirmed that using cellulose based materials in home decoration and renovation, and adding new furniture during early childhood and pregnancy could be risk factors for childhood asthma. The association between household decoration during early childhood and childhood asthma may be stronger in the northern cities of China.