Associations of exposure to green space with problem behaviours in preschool-aged children

Background Limited evidence is available regarding the association of green-space exposure with childhood behavioural development. This study aimed to investigate the associations of exposure to green space with multiple syndromes of behavioural development in preschool children. Methods This cross-sectional study was conducted in Wuhan, China from April 2016 to June 2018. We recruited a sample of 6039 children aged 5–6 years from 17 kindergartens located in five urban districts of the city. We measured the greenness using average Normalized Difference Vegetation Index (NDVI) within a circular buffer area of 100 metres surrounding the central point of residences and kindergartens. We calculated the residence–kindergarten-weighted greenness by assuming that children spent 16 hours per day at home and 8 hours at kindergarten. The problem behaviours of children were evaluated at kindergarten using the Childhood Behavioral Checklist (CBCL) and standardized into problem behavioural T scores. Linear mixed-effect models and linear-regression models were used to estimate the associations. Results We observed decreases in problem behaviours associated with kindergarten and residence–kindergarten-weighted surrounding greenness in preschool children. For example, a one-interquartile range increase in kindergarten and residence–kindergarten-weighted NDVI was associated with decreased T scores for total behaviour by −0.61 [95% confidence interval (CI): −1.09, −0.13) and −0.49 (95% CI −0.85, −0.12), anxiety and depression by −0.65 (95% CI: −1.13, −0.17) and −0.46 (95% CI: −0.82, −0.10), aggressive behaviour by −0.53 (95% CI: −1.01, −0.05) and −0.38 (95% CI: −0.75, −0.02) and hyperactivity and attention deficit by −0.54 (95% CI: −1.01, −0.07) and −0.48 (95% CI: −0.83, −0.12), respectively. Stratified analyses indicated that the associations of green-space exposure with problem behaviours were stronger in boys than in girls. Conclusions Children attending kindergartens with higher levels of surrounding green space exhibited better behavioural development. The mechanisms underlying these associations should be explored further.