The Association Between Exposure to Greenness and Blood Pressure in Children: Findings from the Seven Northeastern Cities Study in China
34 Pages Posted: 15 May 2019More...
Background: There is scarcity of evidence on the associations between greenness and blood pressure, particularly in children. We aimed to investigate this association among children living in China.
Methods: Our study included 9,354 children (4·3 to 17·8 years of age) participating in the Seven Northeastern Cities Study in China. Greenness around each child's school was estimated by NDVI (Normalized Difference Vegetation Index) and SAVI (Soil-Adjusted Vegetation Index). Particulate matter <1μm (PM1) and nitrogen dioxide (NO2) concentrations were predicted by spatiotemporal models. Associations between greenness and blood pressure were determined by generalized linear mixed-effect models. Mediation by air pollution, physical activity and body mass index was assessed using causal mediation analysis.
Findings: Higher greenness was consistently associated with lower blood pressure. An increase of 0·1 in NDVI corresponded to a reduction in SBP of 0·71 mmHg (95% CI: 0·18, 1·23) and lower odds of hypertension (OR= 0·81, 95% CI: 0·72, 0·92). Stronger associations were observed in children with higher BMI. Ambient PM1 and NO2 mediated 24·2% and 19·6% of the association between greenness and SBP, respectively.
Interpretation: Greater greenness had a beneficial effect on blood pressure among Chinese children, particularly in overweight or obese children. The associations were partially mediated by air pollution. If confirmed in future studies, these results could encourage policy makers to incorporate more greenspace for both aesthetic and health benefits.
Funding Statement: This work was supported by grants 81872582, 91543208, 81673128, and 81703179 from the National Natural Science Foundation of China, grant 2018B030312005 from the Guangdong Provincial Natural Science Foundation Team Project, grants 201807010032 and 201803010054 from the Science and Technology Program of Guangzhou, grant 2016YFC0207000 from the National Key Research and Development Program of China, and grants 2016A030313342, 2017A050501062, and 2018B05052007 from the Guangdong Province Natural Science Foundation
Declaration of Interests: The authors state: "none reported."
Ethics Approval Statement: This study was approved by the Human Studies Committee of Sun Yat-sen University.
Keywords: greenness; blood pressure; childhood hypertension; modification; mediation
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