Association between particulate matter exposure and acute ischemic stroke admissions in less-polluted areas: a time-series study using a distributed lag nonlinear model

China has experienced a heavy public health burden due to the increasing incidence of ischemic stroke (IS). Few studies have evaluated the relationship between particulate matter (PM) exposure and acute ischemic stroke (AIS) in relatively less-polluted areas, and the results have been inconsistent. As a result, this study aimed to investigate and evaluate the association between PM exposure and hospitalizations for AIS in an area with less air pollution.

Through collecting daily AIS hospitalizations, air pollution data and meteorological data from July 1, 2017 to June 30, 2020 in Nanning, this paper explored the association between short-term exposure to PM (PM_2.5, PM₁₀ and PM_c) and daily hospital admissions for AIS using a distributed lag non-linear model based on time-series. To further identify the susceptible populations, stratified analyses were performed by age and gender.

During the study period, a total of 2382 patients were admitted to hospital with AIS, with the ratio of male to female reached 2.03: 1. No statistical association was found between PM exposure and AIS admissions in the total population. Subgroup analysis showed that PM_2.5, PM₁₀ and PM_c exposures were significantly associated with AIS admissions in male at lag29-lag30, lag27-lag30 and lag25-lag27, respectively. In addition, PM_c exposure was also relevant to admissions for AIS with aged < 65 years at lag18-lag23.

Short-term exposure to ambient PM was not associated with hospital admissions for AIS in the general population, but males and young adults (aged < 65 years) were more susceptible to PM exposure. Even in areas with relatively low air pollution, appropriate measures should be adopted to intervene in the adverse effects of air pollution on vulnerable populations.