BACKGROUND
Health benefits of urban green space have been widely reported in literature, but the biological mechanisms remain unexplored and a causal relationship cannot be established between green space exposure and cardiorespiratory health.
OBJECTIVE
We conducted a panel study using personal tracking devices to continuously collect the individual exposure data in healthy Chinese adults aged 50 to 64 years living in Hong Kong.
METHODS
A panel of cardiorespiratory biomarkers were tested each week for a period of consecutive five weeks. Weekly exposure to green space, air pollution and physical activities of individual participants was collected by personal tracking devices. The effects of green space exposure measured by the Normalized Difference Vegetation Index (NDVI) at the buffer zones of 100-, 250- and 500-meters on a panel of cardiorespiratory biomarkers were estimated by a generalized linear mixed-effects model, with adjustment for confounding variables of sociodemographic characteristics, exposure to air pollutants and noise, exercises and nutrient intakes.
RESULTS
A total of 39 participants (mean age 56.4 years, range 50-63 years) were recruited and followed up for five consecutive weeks. After adjustment for sex, income, occupation, physical activities, dietary intake, noise and air pollution, significant negative associations with the 250m-buffer NDVI were found in total cholesterol (-21.6% per IQR increase in NDVI, 95% confidence interval (CI) -32.7%, -10.6%), low-density lipoprotein (LDL-C) (-14.9%, 95% CI -23.4%, -6.4%), glucose (-11.2%, 95% CI -21.9%, -0.5%) and high-sensitivity C-reactive protein (hs-CRP) (-41.3%, 95% CI -81.7%, -0.9%). Similar effect estimates were found for the 100m- and 250m-buffer. After adjustment for multiple testing, the effect estimates of glucose and hs-CRP were no longer significant.
CONCLUSIONS
Health benefits of green space can be found in some metabolic and inflammatory biomarkers. Further studies are warranted to establish the causal relationship of green space and cardiorespiratory health.
CLINICALTRIAL