Objective To evaluate the association between acute ischemic stroke (AIS) occurrence of patients and air pollution in Dalian.
Methods Our study collected hospital records of 3 578 AIS patients from three tertiary Grade A hospitals in Dalian from January 1 to December 31, 2015 and obtained air pollution data of the same period. Spearman correlation analysis was used to evaluate the associations of PM2.5, PM10, NO2, SO2, CO, and O3 concentration on the same day with the AIS recorded. The 1:1 matched case-crossover study design was applied to determine the risk of AIS in relation to the PM2.5 concentraions of previous three days.
Results The incidence of AIS was positively associated with PM2.5, PM10, NO2, SO2, CO, and O3, and the coefficients of correlation (r) were 0.209, 0.122, 0.237, 0.381, 0.272, and 0.377, respectively (Ps < 0.05). Strokes due to large artery atherosclerosis, cardiac embolism, and small artery occlusion were positively associated with all the studied air pollutants (P < 0.05). To be specific, strokes due to small artery occlusion had higher correlation coefficients with PM2.5 (r=0.284), PM10 (r=0.235), NO2 (r=0.280), and SO2 (r=0.685) (Ps < 0.05); strokes due to cardiac embolism had a higher correlation coefficient with CO (r=0.210) (P < 0.05); strokes due to large artery atherosclerosis had a higher correlation coefficient with O3 (r=0.684) (P < 0.05). Each 10 μg/m3 increase in PM2.5 was most associated with AIS at lag 0 day (current day) (OR=1.098, 95%CI:1.034-1.166) (P < 0.05).
Conclusion The concentrations of air pollutants are positively associated with reported AIS occurrence of patients in Dalian, and PM2.5 has no significant lag effect on the AIS occurrence.
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