Green spaces and General Health: Roles of mental health status, social support, and physical activity

Abstract

Green spaces are associated with improved health, but little is known about mechanisms underlying such association. We aimed to assess the association between greenness exposure and subjective general health (SGH) and to evaluate mental health status, social support, and physical activity as mediators of this association. This cross-sectional study was based on a population-based sample of 3461 adults residing in Barcelona, Spain (2011). We characterized outcome and mediators using the Health Survey of Barcelona. Objective and subjective residential proximity to green spaces and residential surrounding greenness were used to characterize greenness exposure. We followed Baron and Kenny's framework to establish the mediation roles and we further quantified the relative contribution of each mediator. Residential surrounding greenness and subjective residential proximity to green spaces were associated with better SGH. We found indications for mediation of these associations by mental health status, perceived social support, and to less extent, by physical activity. These mediators altogether could explain about half of the surrounding greenness association and one-third of the association for subjective proximity to green spaces. We observed indications that mental health and perceived social support might be more relevant for men and those younger than 65years. The results for objective residential proximity to green spaces were not conclusive. In conclusion, our observed association between SGH and greenness exposure was mediated, in part, by mental health status, enhanced social support, and physical activity. There might be age and sex variations in these mediation roles.

Residential Surrounding Greenness, Self-Rated Health and Interrelations with Aspects of Neighborhood Environment and Social Relations

“…These include subjective perception of greenness [21] or selfreports of visiting green space [37], access to public green spaces such as parks as well as objective measures of surrounding greenness at residence, such as the NDVI applied in our study. Nevertheless, other studies that used objective measures of greenness as exposure variable and self-rated health as an outcome show results that point in the same direction as ours [20,38,39].…”

“…The role of social contacts in the association between greenness and health has been investigated in a previous study [19] which found that loneliness and perceived shortage of social support partially mediated the relation between green space and health. Another study came up with the same result [20] and Sugiyama et al similarly concluded that social coherence may contribute to the relationship between greenness and mental health, but found no empirical evidence for such an association for physical health [21].…”

“…Residential surrounding greenness measured by NDVI thus refers to the general vegetation level in this area. The 100-m buffer was chosen to represent the immediate (Bnext-door^) neighborhood and has also been applied in previous studies using the NDVI [20,30]. For additional analyses, we also calculated the NDVI in a buffer of 1000 m to apply a broader scale of neighborhood.…”

“…Odds ratios for the associations with greenness were calculated for an IQR (=0.1) increase in mean NDVI, as in other studies on residential greenness and health outcomes [20,30,34]. To account for potential confounding factors, we adjusted for age (continuous), sex, employment status, neighborhood-level SEP (unemployment rate, continuous), household size (>1 person, yes/no), BMI (continuous), and smoking (current, former, never).…”

Allergenic potential of urban green zones of the Santa María de Gracia neighborhood (Murcia, SE Spain)

“…Los espacios verdes urbanos, especialmente los ocupados por árboles, aportan importantes beneficios a los habitantes de las ciudades (Nowak et al 2007, Hartig et al 2011, Dadvand et al 2016, Carrus et al 2017, Vaz et al 2017, pero también algunos inconvenientes (Von Döhren & Haase 2015, Cariñanos et al 2017a, Vaz et al 2017, entre los que queremos destacar los problemas de salud ocasionados por la alergia al polen (Thompson & Thompson 2003, Cariñanos et al 2011. Esta situación suscita cada vez más interés, ya que las particularidades del entorno urbano, especialmente la contaminación, hace que los efectos sobre la población sean más notables (Majd et al 2004, Heinrich & Wichmann 2004, Sénéchal et al 2015 incluso cuando las concentraciones polí-nicas sean menores que en entornos rurales (Nicolau et al 2005).…”