Citation:

Wu, J., K. Rappazzo, R. Simpson, G. Joodi, I. Pursell, J. Mounsey, W. Cascio, AND L. Jackson. DISTINCT ECOSYSTEM SERVICES MAY EXERT PROTECTIVE INFLUENCES ON RATES OF AUTISM VS. SUDDEN UNEXPLAINED DEATH. World Conference on Forests for Public Health, Athens, Attica, GREECE, May 08 - 11, 2019.

Impact/Purpose:

To communicate recent eco-health research findings from two ecologic studies that focus on neighborhood greenery, including near-road tree cover. As conference participants are leading international experts on forests, green space and human health, participation will be a highly effective means to broadcast our latest research for application and to network with leaders in the field.

Description:

INTRODUCTION: Two cross-sectional, ecologic studies explored relationships between the prevalence of natural features in populated areas and two major health issues of unknown etiology: autism and sudden unexpected death (SUD). Trees and other greenery in the built environment can buffer air pollutants and promote physical activity, social interaction, and engagement with nature, all of which reduce stress. Therefore, greenery may be protective for these adverse outcomes yet to date has been unexplored. METHOD: Child autism prevalence data were obtained for 543 public elementary school districts throughout California, USA. Rates were derived by school district. SUD incidence was retrieved from emergency medical services in Wake County, North Carolina, USA; rates were assessed at the U.S. Census tract level (n=187). Metrics of urban greenery were calculated by study unit from satellite-derived 30-meter resolution landcover data from the U.S. Multi-Resolution Landcover Characteristics Consortium. In addition to overall landcover composition per unit, metrics included tree cover along major roadways and density of greenway trails. Statistical analyses included Poisson and negative binomial (NB) regression, and spatial lag and Bayesian spatial modeling. RESULTS: Significant protective associations were observed for greenery metrics for both health outcomes, after controlling for covariates. In the autism analysis, greenery metrics were protective only in school districts in the fourth (highest) quartile of major-road density. The strongest predictor was percent tree canopy along major roads (NB adjusted rate ratio [ARR] for a 10% increase = 0.81 [95% CI: 0.73–0.91]). For SUD, the strongest predictor across all study units was density of greenway trails (Poisson ARR for a 1km/km2 increase = 0.82 [95% CI: 0.69–0.97]). Spatial and non-spatial models returned similar results. CONCLUSIONS: While cross-sectional analyses cannot determine causation, the contrasting findings from these two studies suggest distinct, highly plausible pathways by which trees and other greenery may affect autism and SUD rates. In the case of autism, the capacity of near-road trees to buffer vehicular air pollutants is strongly suggested by the strength of the near-road metric and its significance only in units with the highest road densities. Previous research has implicated air pollution in autism; however, limitations of this study include lack of documentation of maternal greenery exposures. In the case of SUD, greenery as a venue for physical activity and other healthful behaviors is implied by the strength of the greenway signal (and that of overall tree cover), plus the lack of significance of near-road tree canopy. Experimental designs are recommended to pursue the implications of these suggestive results. This abstract has been reviewed and approved by the U.S. Environmental Protection Agency. However, it does not necessarily reflect the views and policies of the Agency.

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