Association Between Short-Term Exposure To Air Pollution And Ischemic Stroke Onset In Shenzhen

Objective:The aim of the study was to analyze the association between short-term exposure to air pollution and ischemic stroke onset using the hospitalized cases of ischemic stroke in Shenzhen from 2008 to 2014,as well as environmental and meteorological data during the same period,in order to provide reference for the prevention of ischemic stroke.Methods:This study collected 63,997 cases of ischemic stroke in Shenzhen from2008 to 2014.Spearman's correlation tests were used to estimate the correlation between air pollution and meteorological factors.We used the time-stratified case-crossover design combining with distributed lag nonlinear model?DLNM?to estimate the association between air pollution and ischemic stroke onset.Furthermore,this study explored the variability across gender and age groups.Results:1.Among 63,997 new ischemic stroke cases,38,070 cases were males accounting for 59.49%and 25,927 cases were females accounting for 40.51%.The number ischemic stroke cases increased year by year,and the proportion of male cases increased year by year.Among all cases,6,305 cases were aged 18⁴4 years,26,692cases were aged 45⁶4 years,and 31,000 cases were aged 65 years or older,accounting for 9.85%,41.71%and 48.44%,respectively.The average age of study subjects was63.41 years old,and the age of ischemic stroke onset showed a downward trend in general in Shenzhen from 2008 to 2014.2.The results of the initial single-pollutant models indicated that SO₂,NO₂,PM₁₀and O₃ were associated with ischemic stroke onset,except for CO.Multi-pollutant model showed that exposure to extreme high-SO₂(P₉₉,37.86?g/m³),extreme high-NO₂(P₉₉,116.26?g/m³),extreme high-PM₁₀(P₉₉,145.94?g/m³),extreme high-O₃(P₉₉,111.57?g/m³),and extreme low-O₃?P₁,16.00?g/m³?could increase the risk of ischemic stroke onset.3.The maximum RR value of exposing to extreme high-SO₂ was 1.50?95%CI:1.22-1.84?,appearing at lag0-12,with the maximum RR 1.73?95%CI:1.37-2.18?at lag0-12,1.24?95%CI:0.94-1.64?at lag0-13,1.55?95%CI:1.20-1.99?at lag0-12 and1.47?95%CI:1.13-1.89?at lag0-13 for males,females,the elderly and adults,respectively.4.The maximum RR value of exposing to extreme high-NO₂ was 1.37?95%CI:1.13-1.67?,with the maximum RR 1.45?95%CI:1.15-1.81?at lag0-10,1.26?95%CI:1.01-1.58?at lag0-8,1.54?95%CI:1.20-1.96?at lag0-10 for males,females and the elderly,respectively.5.The maximum RR value of exposing to extreme high-PM₁₀ was 1.26?95%CI:1.04-1.53?,with the maximum RR 1.28?95%CI:1.01-1.64?at la0-12 and 1.38?95%CI:1.09-1.75?at lag0-12 for females and the elderly,respectively.6.The maximum RR value of exposing to extreme high-O₃ was 1.25?95%CI:1.04-1.49?,with the maximum RR 1.30?95%CI:1.03-1.64?at lag0-14 and 1.32?95%CI:1.05-1.66?at lag0-14 for females and the elderly,respectively.The maximum RR value of exposing to extreme low-O₃ was 1.29?95%CI:1.03-1.61?,with the maximum RR 1.38?95%CI:1.07-1.79?at lag0-14 and 1.35?95%CI:1.07-1.70?at lag0-12 for males and adults,respectively.Conclusions:The age of ischemic stroke onset showed a downward trend in Shenzhen from 2008 to 2014.The number of cases increased year by year and the proportion of male cases increased year by year.Exposure to extreme high-SO₂(P₉₉,37.86?g/m³),extreme high-NO₂(P₉₉,116.26?g/m³),extreme high-PM₁₀(P₉₉,145.94?g/m³),extreme high-O₃(P₉₉,111.57?g/m³),and extreme low-O₃?P₁,16.00?g/m³?could increase the risk of ischemic stroke onset.SO₂,NO₂,PM₁₀ and O₃ exerted non-linear and delayed effects on ischemic stroke,and such effects varied with gender and age.These findings may have significant public health implications for the prevention of ischemic stroke.