Neighborhood Green Space and Pregnancy Outcomes: Disentangling Effects from Air Pollution and Noise Exposures

Abstract

Background: While growing evidence suggests urban green space may be associated with improved health, few studies have attempted to disentangle the effects of green space from other spatially clustered physical and social factors. Here we examine the correlation between neighborhood green space, and fine-scale exposure to air pollution, noise and area-level socioeconomic status (SES) within a large birth-cohort. Methods: Using linked administrative data, we identified 70,249 singleton births (from 1999–2002) in Vancouver, British Columbia, Canada. Seasonal residential green space was estimated using 30m Normalized Difference Vegetation Index (NDVI) data for 100m buffers around residential postal codes. Residential noise exposure was estimated using CadnaA software with a focus on transportation-related sources. Residential air pollution exposure was assessed using a number of land use regression models, of which nitrogen dioxide (NO2) is presented here. Area-level SES was measured using household median income data at the census dissemination area level. We assessed the correlation between exposure measures for postal codes of all study participants as well as exposure levels stratified by the lowest and highest quartile income areas. Results: The average NDVI value within 100m of the residential postal code of study participants was 0.25, with small season variation between winter (0.17) and summer (0.26) values. Moderate negative correlations were observed between NDVI values and NO2 air pollution (-0.52) and noise (-0.32) levels. For participants living in the lowest income areas, greenness was significantly lower (0.20 vs. 0.29 NDVI units) and NO2 (18.0 vs. 15.3 µg/m3) and noise (65.0 vs. 62.5 dB) significantly higher compared to those living in the highest income areas. Conclusions: Neighborhood green space is moderately correlated with air pollution and noise exposures and all three exposures vary by area-level SES.