Greenspace access does not correspond to nature exposure: Measures of urban natural space with implications for health research

Abstract

Urban natural spaces have gained increasing attention in the public health agenda due to their reported association with better health outcomes. Improved measurement of urban natural spaces and a better understanding of the relative effects of different types of natural space in different socio-geographical contexts are required to optimize evidence for urban planning. This case study of Metro Vancouver examines relationships between different accessibility and exposure metrics, the distribution of different land cover types across an urban-rural gradient, and the correlation to area-level marginalization. Local land use and land designation data were used to assess accessibility to public greenspace, a high-resolution land cover dataset was used to determine residential exposure to different land cover types, and the widely applied CAN-Marg index was used to obtain information on area-level marginalization. In addition to descriptive statistics, correlation coefficients were computed to determine relationships between the different variables. Access to public greenspace was weakly correlated with measures of residential exposure to natural land cover types. Although residential exposure varied with level of urbanization, access to public greenspace remained relatively constant across the region. Both access and exposure were significantly correlated with three Can-Marg dimensions: residential instability, material deprivation and ethnic concentration. We recommend that future health research include assessment of both access and exposure as distinct measures, as well as consideration of geographical and social context to potentially target urban green planning for maximal population health impacts.