Combined effects of heatwaves and air pollution, green space and blue space on the incidence of hypertension: A national cohort study

Wensu Zhou; Qiong Wang; Rui Li; Aimulaguli Kadier; Wenjuan Wang; Fenfen Zhou; Li Ling

doi:10.1016/j.scitotenv.2023.161560

Combined effects of heatwaves and air pollution, green space and blue space on the incidence of hypertension: A national cohort study

Sci Total Environ. 2023 Apr 1:867:161560. doi: 10.1016/j.scitotenv.2023.161560. Epub 2023 Jan 11.

Authors

Wensu Zhou¹, Qiong Wang², Rui Li¹, Aimulaguli Kadier¹, Wenjuan Wang¹, Fenfen Zhou¹, Li Ling³

Affiliations

¹ Department of Medical Statistics, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China.
² Department of Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China.
³ Department of Medical Statistics, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, China; Clinical research design division, Clinical research center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China. Electronic address: lingli@mail.sysu.edu.cn.

PMID: 36640878
DOI: 10.1016/j.scitotenv.2023.161560

Abstract

Extreme heat exposure has been associated with hypertension. However, its interactive influences with air pollution, green and blue spaces are unclear. This study aimed to explore the interaction between heatwaves, air pollution, green and blue spaces on hypertension. Cohort data enrolled 6448 Chinese older adults aged 65 years and over were derived from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) between 2008 and 2018. Nine heatwave definitions, combining three heat thresholds (92.5th, 95th, and 97.5th percentiles of daily maximum temperature) and three durations (≥2, 3 and 4 days) were used as time-varying variables in the analysis and were the one-year exposure before survival events. Fine particulate matter (PM ≤2.5 μm in aerodynamic diameter (PM_2.5)), the Normalized Difference Vegetation Index (NDVI) and the average proportion of open water bodies were used to reflect the air pollution, green and blue space exposures, respectively. PM_2.5, green and blue space exposures were time-varying indicators and contemporaneous with heatwaves. Mixed Cox models with time-varying variables were fitted to assess the multiplicative and additive interaction of heatwaves, PM_2.5, and green and blue spaces on hypertension, measured by a traditional product term with the ratio of hazard ratio (HR) and relative risk due to interaction (RERI), respectively. A positive multiplicative (HRs >1) and additive interaction (RERIs >0) between heatwaves and higher PM_2.5 levels was observed. There was a synergistic effect between heatwaves and decreasing greenness levels on hypertension incidence on additive and multiplicative scales. No significant interaction between heatwaves and blue space was observed in the analysis. The combined effects of heatwaves, air pollution, green and blue space exposures on the risk of hypertension varied with age, gender, and educational attainment. This study's findings complemented the existing evidence and revealed synergistic harmful impacts for heatwaves with air pollution and lack of green space on hypertension incidence.

Keywords: Air pollution; Blue space; Elderly; Green space; Heatwave; Hypertension.

MeSH terms

Aged
Air Pollutants* / analysis
Air Pollution*
Cohort Studies
Environmental Exposure / analysis
Humans
Hypertension* / epidemiology
Incidence
Parks, Recreational
Particulate Matter / analysis

Substances

Particulate Matter
Air Pollutants