Ambient Air Pollution and Hospitalizations for Ischemic Stroke: A Time Series Analysis Using a Distributed Lag Nonlinear Model in Chongqing, China.

Hao Chen,Mengmeng Li,Ying Xu,Zheng Cheng,Yong Duan,Kexue Pu,Pan Luo,Li Zhou,Jie Fan

doi:10.3389/fpubh.2021.762597

Abstract

Short-term exposure to air pollution has been associated with ischemic stroke (IS) hospitalizations, but the evidence of its effects on IS in low- and middle-income countries is limited and inconsistent. We aimed to quantitatively estimate the association between air pollution and hospitalizations for IS in Chongqing, China. This time series study included 2,299 inpatients with IS from three hospitals in Chongqing from January 2015 to December 2016. Generalized linear regression models combined with a distributed lag nonlinear model (DLNM) were used to investigate the impact of air pollution on IS hospitalizations. Stratification analysis was further implemented by sex, age, and season. The maximum lag-specific and cumulative percentage changes of IS were 1.2% (95% CI: 0.4–2.1%, lag 3 day) and 3.6% (95% CI: 0.5–6.7%, lag 05 day) for each 10 μg/m3 increase in PM2.5; 1.0% (95% CI: 0.3–1.7%, lag 3 day) and 2.9% (95% CI: 0.6–5.2%, lag 05 day) for each 10 μg/m3 increase in PM10; 4.8% (95% CI: 0.1–9.7%, lag 4 day) for each 10 μg/m3 increase in SO2; 2.5% (95% CI: 0.3–4.7%, lag 3 day) and 8.2% (95% CI: 0.9–16.0%, lag 05 day) for each 10 μg/m3 increase in NO2; 0.7% (95% CI: 0.0–1.5%, lag 6 day) for each 10 μg/m3 increase in O3. No effect modifications were detected for sex, age, and season. Our findings suggest that short-term exposure to PM2.5, PM10, SO2, NO2, and O3 contributes to more IS hospitalizations, which warrant the government to take effective actions in addressing air pollution issues.

Highlights

Stroke is a predominant public health concern in the world and the leading cause of death in China, which caused 6.2 million deaths and 132 million disability-adjusted life years globally in 2017 [1, 2]
Our findings suggest that short-term exposure to PM2.5, PM < 10 μm in aerodynamic diameter (PM10), SO2, NO2, and O3 contributes to more ischemic stroke (IS) hospitalizations, which warrant the government to take effective actions in addressing air pollution issues
Temperature was positively associated with O3, and negatively associated with other air pollutants, whereas relative humidity was positively associated with carbon monoxide (CO), and negatively associated with other air pollutants

Summary

Introduction

Stroke is a predominant public health concern in the world and the leading cause of death in China, which caused 6.2 million deaths and 132 million disability-adjusted life years globally in 2017 [1, 2]. Increasing epidemiological evidence has shown a striking relationship between air pollution exposure and IS [6, 7]. Another study by Tian, Y. et al observed a significant increase in hospitalizations for IS with transient increases of PM2.5, SO2, NO2, O3, and CO in China [9]. Most of these studies were conducted in high-income countries, and the scientific evidence that generated in low- or middle-income countries was scarce, especially in China [10]. It was of great importance to explore the associations between air pollution and IS in the southwest

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