Association between air pollution and atopic dermatitis in Guangzhou, China: modification by age and season*

Background The short-term effect of ambient air pollution on atopic dermatitis (AD), along with its effect modifiers, has not been fully addressed. Objectives To examine the short-term associations between air pollution and AD, and to identify effect modifications by age and season. Methods We used the generalized additive model to evaluate the short-term effect of ambient air pollution on daily hospital visits for AD, adjusting for potential confounders. Subgroup analyses were performed to identify potential effect modifications by season and age (< 18 years and ≥ 18 years). Results A total of 29 972 hospital visits for AD were recorded in Guangzhou, China, from 19 January 2013 to 31 December 2017. Among them, 72·8% were visits by children and 51·4% occurred in the cool season. Acute and delayed effects on AD hospital visits were significant for all air pollutants. Stronger effects were seen in the cool season (approximately 1·7–3·0 times higher than effects in the warm season). Stronger effects were also observed in children (approximately 1·3–1·8 times higher than effects in adults). Sensitivity analyses indicated the results were robust. Conclusions Air pollution might be an important trigger for AD in subtropical Guangzhou, China. Children are more vulnerable than adults, and the effects are stronger in the cool season.