Seite - 23 - in Biodiversity and Health in the Face of Climate Change

23 positive associations between how green an environment is and physical activity rates (Kaczynski and Henderson 2007 in Coutts and Hahn 2015). Similar positive associations are also found between ‘blue’ spaces and physical activity rates (Grellier et  al. 2017; White et  al. 2014) (see also Hunter et  al. Chap. 17, this vol- ume). Encouragement of physical activity is particularly important in the context of increases in non-communicable diseases (NCDs) related to inactivity, such as Type 2 diabetes (Cook et  al. Chap. 11, this volume). The other important, and increasingly well recognised, pathway explaining why physiological responses might be seen at rest in ‘natural’ spaces is due to the regu- lating functions of green and blue spaces through moderating noise, air quality and temperatures. In other words, some health benefits are due to the influence that green and blue spaces have on removing or reducing environmental stressors, espe- cially in busy, densely populated urban centres (Hartig et  al. 2014; Coutts and Hahn 2015; Markevych et  al. 2017). Indeed, this also makes physical activity undertaken in urban green spaces potentially more healthy since it could otherwise lead to increased exposure to harmful levels of air pollutants with acute or chronic effects on the respiratory and cardiovascular systems (Mölter and Lindley 2015). However, the ‘absence of stressors’ argument does not explain all associations, such as have been found in studies where physiological responses are seen in response to visual cues with no direct contact, something that points to psychological and socio- cultural factors (Clark et  al. 2014). Due to the interwoven biophysical, psychologi- cal and socio-cultural elements underpinning connections between nature and health some conceptualisations are based on grouped biopsychosocial pathways, specifically pathways that positively influence health through reducing the potential for harm (reducing environmental stresses), restoring capacities (improving recov- ery functions) and building capacities (reducing individual susceptibility to harm) (Hartig et  al. 2014; Markevych et  al. 2017) (see also Marselle et  al. Chap. 9, this volume). The role of reduced exposure to environmental noise is one particularly interest- ing example given that reductions in noise exposure have been given relatively little emphasis in earlier models, e.g. Hartig et  al. (2014), compared to those developed more recently, e.g. Markevych et  al. (2017) and van den Bosch and Sang (2017). Explanatory mechanisms have also been proposed to link noise stress with impacts on cardiovascular, respiratory, immune response and metabolic health through stress-response models (Recio et  al. 2016). Similar processes may apply to some of the other common environmental stressors, in addition to the better known, but still imperfectly understood connections. For example, new research is finding a wider range of connections between air pollution and human health than ever before, not just through morbidity and mortality from cardiovascular and respiratory diseases but also through neurodevelopmental disorders and birth defects (Landrigan et  al. 2018). It should be remembered that environmental stresses also affect other ani- mals and have been linked to biodiversity loss. Although an issue that is particularly acute in urban areas, anthropogenic sources have been found to elevate noise levels 2 Biodiversity, Physical Health and  Climate Change: A  Synthesis of  Recent Evidence