Ambient Air Pollution and Risk for Stroke Hospitalization: Impact on Susceptible Groups.

Stroke is a leading cause of death, and air pollution is associated with stroke hospitalization. However, the susceptibility factors are unclear. Retrospective studies from 2014 to 2018 in Kaohsiung, Taiwan, were analyzed. Adult patients (>17 years) admitted to a medical center with stroke diagnosis were enrolled and patient characteristics and comorbidities were recorded. Air pollutant measurements, including those of particulate matter (PM) with aerodynamic diameters < 10 μm (PM 10 ) and < 2.5 μm (PM 2.5 ), nitrogen dioxide (NO 2 ), and ozone (O 3 ), were collected from air quality monitoring stations. During the study period, interquartile range (IQR) increments in PM 2.5 on lag3 and lag4 were 12.3% (95% CI, 1.1-24.7%) and 11.5% (95% CI, 0.3-23.9%) concerning the risk of stroke hospitalization, respectively. Subgroup analysis revealed that the risk of stroke hospitalization after exposure to PM 2.5 was greater for those with advanced age (≥80 years, interaction p = 0.045) and hypertension (interaction p = 0.034), after adjusting for temperature and humidity. A dose-dependent effect of PM 2.5 on stroke hospitalization was evident. This is one of few studies focusing on the health effects of PM 2.5 for patients with risk factors of stroke. We found that patients with risk factors, such as advanced age and hypertension, are more susceptible to PM 2.5 impacts on stroke hospitalization.