Impact Of Air Pollution On Blood Pressure Of Physical Examination Population In Shijiazhuang

Objective:To investigate the impact of short-term exposure of six air pollutants(SO₂、NO₂、CO、O₃、PM_2.5、PM₁₀)on blood pressure of physical examination population in Shijiazhuang.Methods:1. Study population and methods:The cross-sectional study was conducted in this paper to obtain the questionnaire and medical examination date of the physical examination population people in the three physical examination centers from April 1,2018 to December 31,2018.The questionnaire included age,sex,education level,work unit,smoking status,drinking status,exercise status,labor intensity,and so on.2.Pollutants and meteorological data:The air pollutants data during the study period,including daily pollutant concentration data of six pollutants(SO₂、NO₂、CO、O₃、PM_2.5、PM₁₀)reported by 51 pollutant monitoring stations in Shijiazhuang,were from the Qingyue Open Environment Data Center.The meteorological data including average daily temperature and average daily relative humidity were from the China Meteorological Administration.3.Estimation of individual exposure to air pollutants:The individual exposure of air pollutants was estimated by the ordinary kriging method.The accuracy of the estimated results was evaluated by leave-one cross-validation method,root mean square error and mean absolute percentage error were calculated.4.Correlation analysis of air pollutants and blood pressure:Multiple linear regression was used to analyze the correlation intensity between pollutant and blood pressure（including lag effect and cumulative effect）,and conduct stratification analysis by sex,age and BMI.Regression analysis adjusted for temperature,relative humidity,sex,age,BMI,education level,smoking,drinking,exercise status,outdoor time,labor intensity,diabetes,dyslipidemia,family history of hypertension,use of antihypertensive drugs.The analysis results are expressed as changes in blood pressure for every 10μg/m³ increase in pollutant concentrations.All data analyses was performed using SPSS 18.0 software,with a two sided significance level of 0.05.Results:1.Characteristics of the study population:A total of 6,707 people was included in the study.The average age of the population is 42.33±9.66 years and an average BMI is 24.19±3.41,3884 people are males（57.91%of the study population）.2. Situation of air pollution:During the study period,the measured daily average concentrations of SO₂,NO₂,CO,O₃,PM_2.5 and PM₁₀ reported by stations is 21.6,42.0,1076.8,83.8,68.0 and 133.4μg/m³,respectively.3. Individual exposure estimates:On the day of the physical examination,the average concentration of SO₂,NO₂,CO,O₃,PM_2.5 and PM₁₀ in the total population estimated by ordinary kriging method is 15.9,41.9,985.8,85.0,56.9,120.6μg/m3,respectively,the average temperature is 20.5℃and the average relative humidity is 63.6%.The MAPE calculated by leave-one-out cross-validation is 13.36%-27.45%,the RMSE is relatively small,indicating that the ordinary kriging method has a better estimation accuracy.4. Impact of air pollutant exposure on blood pressureCorrelation between SO₂short-term exposure and blood pressure:Short-term exposure to SO₂ associates with DBP,PP and MAP,all of which has the largest change in blood pressure in cumulative 11 days,for every1 0 μg/m³ increase in SO₂,DBP increased by 1.59mm Hg,PP decreased by1.59mm Hg and MAP increased by 1.05mm Hg.Further stratification analysis shows that short-term exposure to SO₂ has a stronger association with blood pressure in females,people with age≥40 years and BMI≥24.Correlation between NO₂short-term exposure and blood pressure:Short-term exposure to NO₂ associates with DBP,PP and MAP,all of which has the largest change in blood pressure in cumulative 11 days,for every1 0 μg/m³ increase in NO₂,DBP increased by 0.75mm Hg,PP decreased by0.71mm Hg and MAP increased by 0.50mm Hg.Further stratification analysis shows that short-term exposure to NO₂ has a stronger association with blood pressure in males,people with age≥40 years and BMI<24.Correlation between CO short-term exposure and blood pressure:Short-term exposure to CO associates with SBP,DBP,PP and MAP,and has the largest change in blood pressure in cumulative 11 days,lag 10 days,lag 7days,and cumulative 11 days,respectively.For every 10μg/m³ increase in CO,SBP increased by 0.03mm Hg,DBP increased by 0.02mm Hg,PP increased by0.01mm Hg and MAP increased by 0.02mm Hg.Further stratification analysis shows that short-term exposure to CO has a stronger association with blood pressure in males,people with age<40 years and BMI<24.Correlation between O₃short-term exposure and blood pressure:Short-term exposure to O₃ associates with SBP,DBP,PP and MAP,and has the largest change in blood pressure in cumulative 6 days,lag 9 days,cumulative 11 days,and lag 3 days,respectively.For every 10μg/m³ increase in O₃,SBP decreased by 0.22mm Hg,DBP increased by 0.09mm Hg,PP decreased by 0.28mm Hg and MAP decreased by 0.08mm Hg.Further stratification analysis shows that short-term exposure to O₃ has a stronger association with blood pressure in males,people with age<40 years and BMI<24.Correlation between PM_2.5short-term exposure and blood pressure:Short-term exposure to PM_2.5 associates with SBP,DBP,PP and MAP,and has the largest change in blood pressure in lag 7 days,cumulative 11 days,lag 10days,and cumulative 11 days,respectively.For every 10μg/m³ increase in PM_2.5,SBP increased by 0.16mm Hg,DBP increased by 0.34mm Hg,PP decreased by 0.12mm Hg and MAP increased by 0.30mm Hg.Further stratification analysis shows that short-term exposure to PM_2.5 has a stronger association with blood pressure in females,people with age≥40 years and BMI≥24.Correlation between PM₁₀short-term exposure and blood pressure:Short-term exposure to PM₁₀ associates with SBP,DBP,PP and MAP,and has the largest change in blood pressure in lag 7 days,cumulative 11 days,cumulative 11 days,and cumulative 11 days,respectively.For every 10μg/m³increase in PM₁₀,SBP increased by 0.07mm Hg,DBP increased by 0.19mm Hg,PP decreased by 0.16mm Hg and MAP increased by 0.14mm Hg.Further stratification analysis shows that short-term exposure to PM₁₀ has a stronger association with blood pressure in males,people with age≥40 years and BMI≥24.Conclusions:1.The ordinary Kriging method can more accurately estimate the individual exposure of air pollutants.2.The six main air pollutants may have a certain impact on blood pressure.Different pollutants have different effects on blood pressure.Short-term exposure to PM₁₀,PM_2.5,CO may cause SBP to increase,and short-term exposure to O₃ may cause SBP to decrease.Six pollutants may cause DBP to increase.CO may cause PP to increase,and the other five pollutants may cause PP to decrease.Except for O₃,which may cause MAP to decrease,the other five pollutants may cause MAP to increase.The influence of pollutants on blood pressure needs further study.3.There are differences in the sensitive populations affected by different air pollutants.The sensitive populations of PM_2.5,PM₁₀ and SO₂ may be females,people aged≥40 years and BMI≥24.The sensitive populations of CO and O₃ may be males,people aged<40 years and BMI<24.NO₂ sensitive people may be males,people aged≥40 years and BMI≥24.