Examining the influence of PM_2.5-bound metallic elements and potential sources on stroke emergency department visits:...

This study aimed to investigate the impact of short-term exposure PM_2.5 and PM_2.5-bound metallic elements on stroke-related emergency department visits. Using a case-crossover design, data from the National Health Insurance Research Database (NHIRD) identified 25,055 stroke-related emergency department visits and matched them with 50,110 control days from 2017 to 2020 in six selected study areas in Taiwan. Environmental exposure data included PM_2.5 monitoring date and 35 PM_2.5-bound metallic elements from these areas. Conditional logistic regression models were employed for the analysis. The association between overall PM_2.5 exposure and stroke emergency department visits varied by season. Significant positive associations were observed in autumn and winter across lag periods. In autumn, adjusted odds ratios (ORs) from lag 0-3 were 1.086 (95% CI: 1.078-1.095), 1.087 (95% CI: 1.078-1.096), 1.086 (95% CI: 1.077-1.095), 1.094 (95% CI: 1.085-1.103), respectively. Furthermore, during autumn, a variety of 25 PM_2.5-bound metallic elements showed a positive association with stroke, particularly PM_2.5-bound cadmium (Cd). Adjusted ORs for PM_2.5-bound Cd were 1.486 (95% CI:1.385-1.594) at lag 0, 1.500 (95% CI: 1.397-1.611) at lag 1, 1.458 (95% CI: 1.359-1.565) at lag 2, and 1.465 (95% CI: 1.366-1.571) at lag 3. Conversely, specific elements (Sr, Y, Pb, Ga, Cu, Ba, K, Cs, Rb, Nd, and Al) associated with burning sources exhibited notable positive associations in winter. Our study highlights the importance of monitoring PM_2.5 composition changes and mitigate stroke risks posed by diverse metallic elements. Seasonal variability is evident, with autumn and winter showing sustained associations between stroke and PM_2.5 exposure. Notably, winter, especially during celebrations, showed a significant contribution of PM_2.5-bound metallic elements from burning sources.