Is there an association between eye-level greenness and childhood hypertension using street view? Findings from the Seven Northeastern Cities study in China.

There is a lack of evidence regarding associations of eye-level greenness exposure with blood pressure among children. We aimed to investigate the associations between eye-level greenness of different types and pediatric blood pressure in China. From 2012 to 2013, we recruited 9354 children aged between 5 and 17 years in northeast China. Eye-level of greenness was assessed with Street View Greenness (SVG), derived from Tencent Street View images surrounding participants' schools, utilizing a deep machine learning model. Hypertension was defined as blood pressure above the 95th percentile based on the fourth report's guidelines for children and adolescents. Generalized linear mixed-effects regression models were conducted to estimate adjusted odds ratio (aOR) and estimates of childhood hypertension and pediatric blood pressure per interquartile range (IQR) increase of SVG. Mediation analyses including air pollution and exercise time were also performed. We found the significant association of SVG-total with decreased odds of hypertension in Chinese children (aOR=0.83, 95%CI: 0.75,0.91), especially with the decrease of SBP (β= -0.76, 95%CI: -1.09,-0.43). Interestingly, per IQR increase in SVG-tree 800m for trees was associated with lower adjusted odds of pediatric hypertension (aOR=0.84; 95%CI: 0.76-0.92), also with the decrease of systolic blood pressure. Mediation analyses showed that hypertension was significantly mitigated by lower levels of air pollutants, including PM, PM, SO and NO. Results of this study suggested that eye-level greenness, especially trees, were associated with lower prevalence of hypertension in children, with air pollution exhibiting mediating effects. These findings emphasized the importance of incorporating more greenness, especially trees in both urban planning and public health interventions.