The relationship between atopic dermatitis and indoor environmental factors : a cross-sectional study among Japanese elementary school children

Objectives: This study aimed to determine that home environmental factors were associated with atopic dermatitis in Japanese elementary school children. Methods: In this cross-sectional study, a total of 4,254 children in 12 public elementary schools in Sapporo city in Hokkaido, Japan were examined. Atopic dermatitis was defined using the International Study of Asthma and Allergies in Childhood questionnaire. The questionnaires also contained 14 questions about the child’s home environment. To obtain multivariate-adjusted ORs for atopic dermatitis in relation to the home environment, we controlled for possible confounders including gender, school grade, parental history of allergies, number of siblings, and whether the child was firstborn. The study participants were then divided into two groups according to gender, and a stratified analysis was performed to obtain adjusted ORs for atopic dermatitis in relation to the home environment. Results: The prevalence of atopic dermatitis in our sample was 16.7 %. Using fully adjusted models, the risk factors for atopic dermatitis were found to be the household use of a non-electric heating system without a ventilation duct to the outside (compared to the use of an electric heating system), having visible mould in the house, having a mouldy odour in the house, and condensation on the windowpanes in the house odds ratios (OR 1.25–1.54). In our stratified analysis, having visible mould and having a mouldy odour in the house were relevantly found to be risk factors for boys (OR 1.28–1.64). However, these associations were not found among girls. Conclusions: To improve children’s health, further study is needed to corroborate the findings.