Joint Associations of PM10 and Smoking with the Risk of New-Onset Stroke in Middle-Aged and Elderly Chinese Adults: Findings from the CHARLS Cohort Study

Shiqin Chen¹Tian Lv²Weiyu Li¹Liang Yu²Gonghua Pan¹Ting Shen^2*

• ¹Yuhuan Second People’s Hospital, Yuhuan, China
• ²Zhuji Affiliated Hospital of Wenzhou Medical University, Zhuji, China

Background: The relationship between long-term exposure to particulate matter ≤ 10 μm in diameter (PM10), smoking, and stroke risk remains unclear. This study investigates their association. Methods: We analyzed data from 10,839 participants in the 2013 wave of the China Health and Retirement Longitudinal Study (CHARLS). Long-term PM10 exposure was estimated using the China High Air Pollution (CHAP) dataset, and incident stroke cases were self-reported during follow-up through 2018. Multivariable Cox proportional hazards models, restricted cubic spline (RCS) analyses, and joint exposure models were employed. Results: Each 1 μg/m³ increase in PM10 concentration was associated with a 0.3% higher risk of stroke (HR = 1.003; 95% CI: 1.000-1.005; P = 0.04). A nonlinear exposure-response relationship was observed (P for non-linearity = 0.04). Among PM10 exposure quartiles, only the third quartile (91.90-115.92 μg/m³) was significantly associated with increased stroke risk (HR = 1.36; 95% CI: 1.08-1.71; P < 0.01). Participants exposed to both high PM10 levels (≥ 91.9 μg/m³) and smoking had the highest stroke risk (HR = 1.72; 95% CI: 1.33-2.23; P < 0.01).No significant multiplicative or additive interaction between PM10 and smoking was found.Conclusion: Long-term PM10 exposure and smoking are independent risk factors for stroke.The elevated risk observed within a specific concentration range of PM10 suggests a potential threshold or saturation effect. Individuals exposed to both risk factors are particularly vulnerable, highlighting the need for integrated public health strategies targeting both air -3 -quality improvement and smoking cessation.