Is moving to a greener or less green area followed by changes in physical activity?

Green areas might provide an inviting setting and thereby promote physical activity. The objective of this study was to determine whether moving to different green area surroundings was followed by changes of physical activity. Data from a large population-based cohort of adults in Stockholm County responding to surveys in 2010 and 2014 were analysed (n = 42611). Information about walking/cycling and exercise were self-reported and living area greenness data were satellite-derived (NDVI, Normalized Difference Vegetation Index). Multinomial logistic regression analyses were performed separately for changes in levels of walking/cycling and exercise (decrease, stable, increase). Greenness was defined as a change in NDVI quartile to less green, same, or greener. Odds ratio's (OR) with 95% confidence intervals (CI) were presented adjusted for gender, age, education and area-based income. Contrary to what we hypothesized, those moving to a greener area were more likely to decrease their levels of walking/cycling (OR = 1.42, CI = 1.28-1.58), whereas those moving to a less green area were more likely to increase their walking/cycling (OR = 1.26, CI = 1.13-1.41). Exercise behaviour showed another pattern, with people being more likely to decrease exercise both when moving to a greener (OR = 1.25, CI = 1.22-1.38) and to a less green area (OR = 1.22, CI = 1.09-1.36). Studying subpopulations based on sociodemographic characteristics did not aid to clarify our results. This cohort study with repeated measurements did not support the currently available cross-sectional studies showing a strong positive relation between greenness and physical activity. Nevertheless, our findings have shown spatial patterns related to green areas and physical activity which imply a need for place-specific health policies.