Air pollution and longitudinal functional recovery in stroke survivors—a longitudinal cohort study from central China

Stroke survivors face a profound burden from functional impairment, but the impact of long-term ambient air pollution on the longitudinal recovery trajectories of activities of daily living (ADL) remains unclear. We aimed to determine the longitudinal associations between long-term exposure to multiple air pollutants and functional recovery in stroke survivors. A longitudinal cohort study was conducted using electronic medical record data from July 1, 2019, to December 31, 2025, in Xiangyang, a highly polluted region in central China. The study included 1,755 patients with incident ischemic or hemorrhagic stroke who had at least 2 complete ADL assessments. Long-term residential exposure to ambient fine particulate matter (PM 2.5 ), inhalable particles (PM 10 ), nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ), carbon monoxide (CO), and ozone (O 3 ) was assessed. The primary outcome was functional change measured by the Modified Barthel Index (MBI). Secondary outcomes included MBI score decline and ADL dependence (defined as MBI score < 60). Inverse probability weighting (IPW)-adjusted models and restricted cubic splines were applied for analysis. The study included 1,755 stroke survivors (1,102 [62.8%] male; 1,171 [66.7%] aged < 65 years; 855 [48.72%] ischemic stroke) with 6,334 follow-up visits. In IPW-adjusted models, a 10 µg/m 3 increase in PM 2.5 was associated with a significant decrease in MBI score (-11.11; 95% CI, -21.34 to -0.88) and an increased risk of ADL dependence (OR, 1.65; 95% CI, 1.18–2.30). Significant functional declines were also associated with interquartile range increases in NO 2 (-7.44; 95% CI, -11.54 to -3.33), SO 2 (-6.06; 95% CI, -12.26 to -1.53), and CO (-0.39; 95% CI, -0.71 to -0.07). Restricted cubic spline analyses suggested non-linear inverse associations of PM 2.5 , NO 2 , and SO 2 with the probability of ADL independence, with more pronounced declines at higher exposure levels. Patients with ischemic stroke were significantly more susceptible to PM 2.5 and CO exposures than those with hemorrhagic stroke. Long-term exposure to PM 2.5 , NO 2 , SO 2 , and CO is significantly associated with hindered functional recovery and increased ADL dependence in stroke survivors. These findings underscore the need for stringent air quality interventions to improve post-stroke rehabilitation outcomes.