Green space type and healthy ageing in place: An Australian longitudinal study

Abstract

Research on the health benefits of people’s long-term exposure to green space is lacking. Addressing this emerging topic, this study uncovers the association of green space types with a person’s healthy ageing score (HAS). We investigated the association with HAS by continuous exposure to various green space types for two years. Green space types include tree canopy, low-lying vegetation and open grass percentage within 1.6-km road network distance buffers at baseline and second follow-up. Healthy ageing outcomes included functional capacity, resilience and HAS while accounting for relocation. This is a longitudinal study of a cohort of 22,715 New South Wales residents aged over 45 who participated in the Sax Institute’s 45 and Up Study living in Sydney, Wollongong and Newcastle. Longitudinal models of healthy ageing on green space types were fit with controls for socioeconomic confounders. Women who did not relocate were associated with a lower functional capacity (β; 95%CI: −0.10; −0.15,−0.05) and higher resilience (0.11; 0.08, 0.14) compared to those who relocated. Apart from age, personal characteristics did not explain the variation in healthy ageing outcomes for participants who moved. For participants who did not relocate, 30% grass cover was associated with decreased functional capacity (−0.22; −0.41,−0.04) and HAS (−0.31; −0.56,−0.05). Also, 5–9% low-lying vegetation was associated with a decline in functional capacity (−0.09; −0.15, −0.03) and HAS (−0.09; −0.17, −0.01) of participants who stayed but improved resilience (0.28; 0.01, 0.55) of participants who relocated. Green space comprising over 30% tree cover appeared most beneficial for functional capacity (0.42; 0.31, 0.53), resilience (0.19; 0.13, 0.25) and HAS (0.60; 0.45, 0.75). For participants who relocated, over 30% tree canopy was associated with improved functional capacity (0.33; 0.54, 0.62) but not resilience or their HAS. Increased neighbourhood tree canopy supports healthy ageing. Older people should be supported to live in-home or move into nearby residential care and maintain regular contact with green spaces and trees, to maximise potential benefits for health and wellbeing.