Inverse relationship between urban green space and childhood autism in California elementary school districts
The prevalence of childhood autism was less in school districts with greater near-road canopy
Do neighborhoods with more green space have a lower prevalence of childhood autism? Researchers hypothesized that this might be so and analyzed relevant data to explore the possibility. This data included information about multiple types of green space in California elementary school districts and autism prevalence in those districts. Green space measurements included percentages of forest, grassland, and average tree canopy and near-road tree canopy for 543 public elementary school districts in California. While other studies have considered possible environmental factors related to the increasing prevalence of childhood autism, this study is the first to examine near-road tree canopy and its possible influence on childhood autism in urban areas. The purpose of the study was to examine whether green space exposure could help reduce the prevalence of childhood autism.
The prevalence of autism in these California school districts ranged from 0 to 79 cases per 1000 children. The average prevalence was 6.8 cases per 1000 children. The major land cover types in these districts were 21.89% agriculture, 20.86% forest, 16.44% grassland, and 16.16% urban land.
Results indicated that as several green space measures increased, the prevalence of autism decreased. This was especially true for the percentage of forest, the average tree canopy, and the near-road tree canopy. These associations held even after adjusting for race, gender, and socioeconomic factors. The associations were significant, however, only in school districts with high road density.
This research suggests that tree cover in areas with high road density may influence the prevalence of autism in elementary school children. The authors suggest that near-road tree canopy may have protective effects on autism prevalence in highly urbanized areas by reducing exposure to traffic-related air pollution and decreasing maternal stress associated with noise. While this study cannot confirm that green space exposure caused a decrease in childhood autism, the findings do indicate that “increasing tree cover might be a practical and beneficial measure to mitigate increasing autism prevalence.”
Citation
Wu, J., Jackson, L., (2017). Inverse relationship between urban green space and childhood autism in California elementary school districts. Environment International, 107,
