The impacts of multidimensional urban greenness on incident dyslipidaemia and blood lipid profiles among adults: A 10-year longitudinal cohort study in Hong Kong.

Although the health benefits of greener environments are well documented, longitudinal evidence linking multidimensional greenness to blood lipid health, a key risk factor for cardiovascular diseases, remains limited, particularly in high-density urban settings. This 10-year (2008-2017) cohort study investigated the associations between multidimensional greenness and lipid health in Hong Kong. We assessed aerial greenness, street-level visibility (Green View Index), and three-dimensional greenness volume at each participant's addresses. We examined the associations between greenness and blood lipid profiles (total cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol) and the development of dyslipidaemia among 24,458 adults and 6,239 adults, respectively. Using time-varying Cox regression models and linear mixed-effects models, we found that each interquartile range increase in all greenness metrics was associated with 8-14% reduced risk of the development of dyslipidaemia. All greenness metrics were also associated with healthier levels of lipid profiles. Notably, we identified potential thresholds (1.1 m3) for the health impacts of three-dimensional greenness volume, which require an increase of approximately 37.5% above current average levels in Hong Kong. Mediation analyses revealed that fine particulate matter significantly mediated up to 40.39% of the impact of three-dimensional greenness volume on the development of dyslipidaemia. Non-elderly adults and female participants appeared to derive smaller health benefits from greenness. These findings provide quantitative targets for urban greening, and also a mechanistic justification for using nature-based solutions to build a sustainable healthy city.