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.