Investigation of Neighborhood Greenspace as Protection Against Development of Childhood Asthma

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PROJECT SUMMARY/ABSTRACT Emerging evidence suggests that exposure to vegetated land cover, or ‘greenspace’, particularly in early life, may prevent development of asthma. One proposed mechanism behind this relationship describes microbial diversity of natural landscapes contributing to diverse microbiome profiles in children who live nearby, thus supporting robust immune development. Another proposed mechanism involves removal of asthma-causing air pollutants by tree canopy. We propose a study of neighborhood greenspace in relation to the asthma incidence, in a longitudinal cohort of over 170,000 children living in the Philadelphia metropolitan region, followed from infancy. In the proposed study, we will link electronic health records (EHR) from the defined cohort to high-spatial resolution greenspace metrics, by children’s individual geocoded addresses. Our rich database will also include an array of additional environmental and sociodemographic measures of the neighborhoods where children live, needed to disentangle the individual effects of greenspace from other neighborhood factors, and also enabling a meaningful analysis of the joint effects of greenspace with other conditions that may enhance or diminish the potential greenspace benefits. In our study, we specifically aim to: 1) Investigate the association between neighborhood greenspace and asthma incidence from infancy through childhood (specifically, ages 2, 7 and 12) in a cohort of urban and suburban children; 2) Evaluate modification of the relationship between greenspace and asthma incidence by other neighborhood characteristics that may alter risk or vulnerability, including air pollution (PM2.5, O3), traffic, urban status, and sociodemographics; and, 3) Describe heterogeneity of the association with neighborhood greenspace among asthma phenotypes. We will evaluate several greenspace measures in relation to asthma incidence, including overall greenness, tree canopy coverage, grass/shrubs, natural landcover diversity, and spatial attributes of green spaces (e.g., patch size, aggregation), and we will investigate these measures as time-window specific (e.g., infancy) and cumulative greenspace exposures during follow-up. Our study will provide a robust analysis of the potential for urban greenspace exposure in early life to protect against development of asthma. In addition, information from subgroup and phenotype analyses may provide clues regarding the mechanisms by which greenspace may affect risk of asthma, as well as the scope of potential impact.