Seite - 109 - in Biodiversity and Health in the Face of Climate Change

109 5.3.5 Green Space Metrics, Buffers and  Data Used A number of studies estimated green space or urban greenness with the average Normalised Difference Vegetation Index (NDVI; Abelt and McLafferty 2017; Cohen-Cline et  al. 2015; McMorris et  al. 2015; Paquet et  al. 2013; Triguero-Mas et  al. 2015; Xu et  al. 2017). The NDVI is a measure of urban greenness based on remote sensing data. Others use green space classifications based on land use or land cover data in offi- cial statistics (Feda et  al. 2015; McMorris et  al. 2015; Abelt and McLafferty 2017; Cusack et  al. 2017; Mukherjee et  al. 2017). Several studies use a distinct distance or buffer size from the residential place ranging from 30  m to 1000  m (Cusack et  al. 2017; McMorris et  al. 2015; Abelt and McLafferty 2017; Mukherjee et  al. 2017; Feda et  al. 2015). Remaining studies apply land-use and land cover data from official national or local statistics. Here urban green is classified as urban parks, urban woodlands or for- est areas. Nearly half of the studies use buffer sizes of 500  m around a residential place or neighbourhood followed by a 250-m and 300-m distance. Those areas should reflect a walking distance of around 10  min to the next available green space of a certain size. In general, it cannot be concluded that the results differ depending on the green space measurement, data or buffer size used (for further discussion, see de Vries and Snep Chap. 8, this volume). 5.3.6 Confounding Factors Many studies researched the relationship between health outcome and urban green space exposure or availability while controlling for confounding factors in their sta- tistical models. The articles selected for our review used a number of different socio- economic and socio-demographic variables (Figs.  5.2 and 5.3). Socio- economic education income neighborhood deprivation employment status socio economic status (SES) car ownership poverty indication tenure status number of crimes reported 0 5 10 15 20 No. of articles Fig. 5.2 Socio-economic confounders 5 The Influence of  Socio-economic and  Socio-demographic Factors in  the  Association…