Association between the density and type of trees around urban schools and exhaled nitric oxide levels in schoolchildren.

Abstract

Greenspaces in school's neighbourhood represent an important environment to promote healthy development. The aim of this study was to assess the association between the density and type of trees around schools and exhaled Nitric Oxide (NO) levels in schoolchildren. Data on 845 children from 20 primary schools in Porto was analysed. Airway inflammation was assessed by measuring exhaled NO level. The density and type of trees were quantified within a 500 m buffer around schools. Associations were estimated using mixed-effect models. A significant association was observed between non-tree covered areas around schools and exhaled NO levels in schoolchildren (β = - 1.42, 95% CI - 2.84, - 0.001). Our results suggested that the presence of trees in school neighbourhoods may play a role in the biological mechanisms underlying the complex links between environment and airway inflammation.