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Published on: September 16, 2017
Temporal Variations in the Association between Short-Term Exposure to PM2.5, Its Components, and Ischemic Stroke
Zhaoyang Pan1, Xueyan Han1, Xuewei Xie2,3
1School of Health Policy and Management, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730, China.
Abstract:
Approximately 16% of stroke-related deaths can be attributed to PM2.5, and extensive evidence has consistently linked short-term exposure to PM2.5 to an increased risk of ischemic stroke onset. However, most previous studies rely on the assumption of a constant impact of PM2.5 over time, despite emerging evidence on the time-variant nature of PM2.5-associated health effects. This study aims to assess the temporal changes in the association between PM2.5 and its components and the risk of ischemic stroke. We employed the case-crossover design and included 1,625,763 participants from the Chinese Stroke Center Alliance (CSCA) program. Conditional logistic models were used to estimate the acute effect of PM2.5 and its components on the ischemic stroke onset. Temporal changes in PM2.5 and its components were evaluated across two periods (2015-2017 and 2018-2022) and annually. A 10 μg/m3 increase in PM2.5 at lag 0 day demonstrated a stronger association with ischemic stroke during Period 1 (percent change in risk: 0.54% [0.42 to 0.65%]) compared to Period 2 (0.29% [0.19 to 0.38%]), indicating a significant decline of -0.25% (-0.40 to -0.10%). This decreasing trend was consistent across five PM2.5 components, particularly for black carbon (BC), which exhibited the largest reduction (-4.47% [-7.47, -1.38%]). Nonlinear exposure-response curves for PM2.5 and its components also exhibited a steeper trend in Period 1. By integrating individual ischemic stroke onset data from over 2,600 hospitals across China, our study demonstrates a declining trend in the health effects of PM2.5 and its chemical components on ischemic stroke onset. These findings highlight the importance of accounting for temporal variations in PM2.5-related health effects when estimating disease burden, designing and evaluating air pollution control policies, and informing public health decision-making.
Insights
Particulate matter (PM2.5) exposure is linked to ischemic stroke. This study found that the association between PM2.5 and stroke risk has decreased over time, especially for black carbon. Air quality improvements are reducing health impacts.
Area of Science:
- Environmental Health
- Epidemiology
- Cardiovascular Disease
Background:
- Particulate matter (PM2.5) exposure is a significant risk factor for stroke-related mortality and morbidity.
- Previous research often assumed a constant association between PM2.5 exposure and health outcomes, overlooking temporal variations.
- Understanding time-varying effects of PM2.5 is crucial for accurate health burden assessment and policy evaluation.
Purpose of the Study:
- To investigate the temporal changes in the association between fine particulate matter (PM2.5) and its components with ischemic stroke risk.
- To quantify the decline in PM2.5-attributable ischemic stroke risk over different time periods in China.
- To assess the impact of air pollution control policies on the health effects of PM2.5.
Main Methods:
- Utilized a case-crossover design with a large cohort of 1,625,763 participants from the Chinese Stroke Center Alliance (CSCA) program.
- Employed conditional logistic models to estimate the acute effects of PM2.5 and its components on ischemic stroke onset.
- Analyzed temporal trends in PM2.5 and component associations with stroke risk across 2015-2017 and 2018-2022, and annually.
Main Results:
- A 10 μg/m3 increase in PM2.5 was associated with a 0.54% increased risk of ischemic stroke in 2015-2017, significantly lower than 0.29% in 2018-2022.
- This decreasing trend in PM2.5's health impact was observed across multiple components, with black carbon showing the most substantial reduction.
- Nonlinear exposure-response curves for PM2.5 and its components were steeper in the earlier period (2015-2017).
Conclusions:
- The health effects of PM2.5 and its components on ischemic stroke onset have significantly declined in China.
- Temporal variations in PM2.5-related health risks must be considered for accurate disease burden estimation and policy effectiveness.
- Findings underscore the positive impact of air pollution control measures on public health, specifically reducing stroke incidence.
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