Health Effects of Neighbourhood Greenness on Chinese Adults: Analysis of Two Existing Longitudinal Cohorts in Taiwan and Hong Kong

Description

AimThe overall aim of this proposed project is to investigate the effects of neighbourhood greenness on various health outcomes in two longitudinal cohorts comprising 676,233 Chinese adults.Project backgroundMore than half of the global population resides in urban areas, and this proportion is expected to increase to 68% by 2050. A recent proposal for improving public health is to improve neighbourhood greenness, which is one of the important elements of the urban environment. There are studies that have investigated the association between greenness and health, but few of these are large longitudinal cohort studies, which generally provide reliable and robust results. Furthermore, most cohort studies have been conducted in Western countries and have only assessed a limited number of health outcomes, such as cardiovascular diseases. Data are especially scarce on the health benefits of neighbourhood greenness in the context of Asian regions, where the ethnicity, culture, population density and urbanisation differ substantially from Western countries. Moreover, multiple complex pathways that link greenness to various health outcomes remain unclear. It has been hypothesised that greenness may affect population health by reducing air pollution and promoting physical exercise. In addition, socioeconomic status plays an important role in health inequality. However, few studies have examined the mediating effects of these factors.Project descriptionWe propose to investigate this important public health topic using data from two existing longitudinal cohorts in Taiwan and Hong Kong. The two cohort databases contain 1.50 million medical examination records from approximately 670,000 individuals for the 1996–2019 period. These databases contain the demographic, socio-economic, lifestyle, medical history, and exercise data collected during each medical examination. In our previous study, we obtained data on the participants’ air pollution exposure (including PM2.5, nitrogen dioxide and ozone) and vital statistics (for the Taiwan cohort). In the proposed project, we plan to derive normalised difference vegetation index and enhanced vegetation index values from moderate-resolution imaging spectroradiometer vegetation index products at a resolution of 250 m × 250 m and use them as indicators of greenness. A Cox regression model will be used to analyse data corresponding to dichotomous health outcomes (mortality and morbidities), while a generalised linear mixed model will be used to analyse data for continuous health outcomes (e.g. lung function, blood pressure and glucose levels). Mediation analyses will be used to examine the mediating effects of socioeconomic status, the level of exercise and air pollution exposure on the associations between greenness and various health outcomes.Significance of the projectAn enhanced understanding of the health effects of neighbourhood greenness will have important implications for the development of health guidelines and urbanisation policies, especially in Asian regions, where urbanisation is occurring rapidly, leading to high population densities.