Effects Of Short-term Exposure To Air Pollution On The Hospitalization Risk Of Ischemic Stroke In Ningxia Province: A Time-series Analysis

Objective To analyze the effects of short-term exposure to air pollution on the hospitalization risk of ischemic stroke in Ningxia Province,and to further explore the differences in the hospitalization risk of ischemic stroke in different seasons,genders,and ages.Methods To collect the relevant information on patients who were hospitalized for ischemic stroke from 2015 to 2020 in Ningxia Province,as well as the air pollution data and meteorological data during the same period.The generalized additive model of time series study was used to explore the effects of short-term exposure to air pollution on the hospitalization risk of ischemic stroke.The single-day lag and multi-day cumulative lags of PM_2.5,PM₁₀,SO₂,NO₂,O₃,and CO on the hospitalization risk of ischemic stroke were calculated.Meta-analysis was used to combine the effect values of each city.We investigated the nonlinear concentration-response relationship between air pollution and the hospitalization risk of ischemic stroke and identified the sensitive population according to gender,age,and season in the lag days with the strongest effect value.Change the degree of freedom of model parameters and establish a double-pollution model for sensitivity analysis to verify the stability of the single pollution model.Results1.A total of 153,075 inpatients with ischemic stroke from 2015 to 2020 in Ningxia Province were included in this study,with an average daily hospitalization of 70±37,the number of male inpatients（80207）was slightly higher than that of female patients（72868）.There were more patients aged 65 years or older,accounting for 65%,and the number of inpatients was the same in the cold and warm seasons（warm season:76287,cold season:76780）.2.The daily average concentration of PM_2.5,PM₁₀,SO₂,NO₂,O₃and CO respectively were 40μg/m³,97μg/m³,28μg/m³,29μg/m³,96μg/m³and 0.8mg/m³in Ningxia Province.The days in which the daily average concentration were exceed air quality standards were 181days（accounting for 8.30%）,251 days（accounting for 11.45%）,3 days（accounting for0.14%）,0 days（accounting for 0.00%）,49 days（accounting for 2.24%）,0days（accounting for 0.00%）.3.Short-term exposure to six air pollutants increases the risk of hospitalization for ischemic stroke.A 10μg/m³increment in concentrations of PM_2.5,PM₁₀,SO₂,NO₂,and was were associated with 1.37%（95%CI:0.70%,2.04%）、0.07%（95%CI:0.01%,0.15%）、0.78%（95%CI:0.30%,1.26%）、2.19%（95%CI:1.23%,3.15%）、0.5%（95%CI:0.21%,0.79%）increases the daily number of inpatients in ischemic stroke,and a 0.1mg/m³increment in concentration of CO was associated with 0.88%（95%CI:0.61%,1.16%）increases the daily number of inpatients in ischemic stroke.4.Gender stratified analysis:There was a gender difference in the effect of short-term exposure to air pollutants on the risk of hospitalization in patients with ischemic stroke,with women being more susceptible.Short-term exposure to PM_2.5and CO poses a greater risk of hospitalization in women with ischemic stroke.There was a significant correlation between SO₂,NO₂,and O₃and the hospitalization risk of female patients,and only PM₁₀was significantly associated with the risk of hospitalization in male patients.Age-stratified analysis:There was an age difference in the effect of short-term exposure to air pollutants on the risk of hospitalization in patients with ischemic stroke,with people younger than 65 years being more susceptible.Short-term exposure to PM₁₀and O₃was associated with a greater risk of hospitalization in ischemic stroke patients less than 65 years of age,PM2.5 and SO2were significantly associated with the risk of hospitalization in patients less than 65 years of age,and NO2 and CO were significantly associated with the risk of hospitalization in patients greater than or equal to 65 years of age.Seasonal stratified analysis:There were differences in the risk of hospitalization for ischemic stroke patients between different air pollutants in the cold and warm season.There was no significant difference in the risk of hospitalization caused by PM10 and O₃in ischemic stroke patients during the cold and warm season,and NO₂and CO caused a higher risk of hospitalization in ischemic stroke patients during the cold season than during the warm season.The risk of hospitalization caused by PM_2.5and SO₂in the warm season is higher than in the cold season.Conclusion1.PM_2.5,PM_10,and O₃were the main air pollutant in Ningxia Province.2.Short-term exposure to PM_2.5,PM₁₀,SO₂,NO₂,O_3,and CO increases the risk of hospitalization in ischemic stroke patients and has a lag effect,with heterogeneity in the maximum effective value of different pollutants and the lag days they appear.NO₂showed an early lag time for the maximum effect value and had a greater impact on the risk of hospitalization for ischemic stroke;this was followed by PM_2.5,with a later lag time for the maxim effective value.SO₂and CO had a moderate effect on the increased risk of ischemic stroke hospitalization,and the maximum effect values were obtained in the early single-day lag and the late cumulative lag,respectively.And PM₁₀,O₃had little effect on the risk of ischemic stroke hospitalization.3.The effects of air pollution on the risk of hospitalization of patients with ischemic stroke are different in gender and age,with females as well as people less than 65 years of age being more susceptible,and different pollutants have heterogeneous effects on the risk of hospitalization in ischemic stroke.NO₂and CO had a stronger effect in cold the season,PM_2.5and SO₂had a stronger effect in the warm season,and PM₁₀and O₃had no significant difference in the cold and warm season.