Association Between Air Pollutants Exposure And The Risk Of Ischemic Stroke Hospital Admission In Nanchang

Objective:To investigate the association between air pollutants exposure and the risk of ischemic stroke(IS)hospital admission in Nanchang,and to identify sensitive populations so as to provide a scientific basis for relevant authorities to develop comprehensive protection strategies and measures for ischemic stroke.Methods:Daily air pollutants(Fine Particulate Matter,PM2.5;Inhalable Particulate Matter,PM10;Sulfur Dioxide,SO2;Nitrogen Dioxide,NO2;Ozone,O3),daily meteorological conditions(average temperature,relative humidity),and daily ischemic stroke hospital admission in Nanchang were collected from 2018 to 2019.We investigated the association between air pollutants exposure and ischemic stroke hospital admission using a generalized additive model(GAM)with a quasi-Poisson link,and subgroup analysis was performed according to sex,age,season,hypertension status,temperature and humidity to identify sensitive populations.Finally,the stability of the model was tested by sensitivity analysis.Results:1.The total number of ischemic stroke hospital admission in 11 hospitals in Nanchang from 1 January 2018 to 31 December 2019 were 25,963,with an overall upward trend,averaging 35.57 per day.61.68% were male,75.64% were 60 years and older,59.45% were in the warm season and 69.47% were combined with hypertension.2.During the period of this study,the average concentrations of PM2.5,PM10,SO2,NO2 and O3 in Nanchang were 30.67μg/m3,64.44μg/m3,8.51μg/m3,31.21μg/m3 and 59.28μg/m3 respectively,and the concentrations of each air pollutant did not exceed the national secondary concentration limit,and the overall levels of air pollutants were low and showed a seasonal trend.The concentrations of PM2.5,PM10,SO2 and NO2 were high in winter and low in summer,while the concentration of O3 was high in summer and low in winter.The average temperature also showed a seasonal trend and there was no obvious pattern in relative humidity.3.The model analysis showed that the five air pollutants were not significantly associated with the risk of ischemic stroke hospital admission from lag0 to lag7.At lag7,ischemic stroke hospital admission increased by 0.25%(95%CI:-0.74%,1.26%)、0.14%(95%CI:-0.35%,0.64%),1.47%(95%CI:-1.72%,4.78%),-0.15%(95%CI:-1.40%,1.12%),0.05%(95%CI:-0.66%,0.76%)for every 10 μg/m3 increase in PM2.5,PM10,SO2,NO2,O3,respectively.PM10,SO2 and NO2 were significantly associated with an increased risk of ischemic stroke hospital admission from lag36 to lag43.At lag40,ischemic stroke hospital admission increased by 0.80%(95%CI:-0.19%,1.81%),0.85%(95%CI: 0.35%,1.35%),5.39%(95%CI: 2.10%,8.79%),2.36%(95%CI: 1.05%,3.68%),-0.23%(95%CI:-0.93%,0.48%)for every10 μg/m3 increase in PM2.5,PM10,SO2,NO2,O3,respectively.4.Subgroup analysis showed that the association between air pollutants exposure and the risk of ischemic stroke hospital admission was significant in the groups aged 60-69 years(O3: lag4),70-79 years(SO2: lag7;NO2: lag7),moderate temperature(NO2: lag0,lag0-1),and high temperature(NO2: lag6)from lag0 to lag7.The association between air pollutants exposure and the risk of ischemic stroke hospital admission was stronger in the groups aged 18-59 years,cold season,combined hypertension,low temperature,and high humidity from lag36 to lag43.Conclusion:The number of ischemic stroke hospital admission in Nanchang is trending upward from 2018 to 2019.The overall level of air pollutants were low,with PM2.5,PM10,SO2,and NO2 concentrations were high in winter and low in summer,while O3 and average temperature were high in summer and low in winter,with no clear pattern of relative humidity.The results of the GAM showed no association between the raised concentrations of the five air pollutants and increased overall risk of ischemic stroke hospital admission from lag0 to lag7,only in the subgroups of 60-69years(O3: lag4),70-79 years(SO2: lag7;NO2: lag7),medium temperature(NO2: lag0,lag0-1),and high temperature(NO2: lag6).PM10,SO2 and NO2 were significantly associated with an increased risk of ischemic stroke hospital admission from lag36 to lag43,especially in the group aged 18-59 years,cold season,combined hypertension,low temperature,and high humidity with greater strength of association.