| Objective In order to clarify the general situation and time variation characteristics of cardiovascular deaths and air pollutants(PM10,SO2,NO2,PM2.5,CO,O3)in Hefei city from 2007 to 2016.We used time series analysis to explore the relationship between air pollutants and cardiovascular diseases deaths and to identify the sensitive population.This study would provide a theoretical basis for elucidating the prevention and control strategies of cardiovascular diseases deaths caused by air pollutants.Methods 1.Daily counts of cardiovascular diseases deaths from 2007 to 2016 were provided by the Hefei Center for Disease Control and Prevention.The case information included age,sex,education level,underlying cause of death and underlying cause of death ICD-10 encoding.The case data were summarized according to the International Classification of Diseases Tenth Revision(ICD-10).The daily air pollutant concentration data,including 24 h PM10,PM2.5,SO2,NO2,CO concentration data and 1 h O3,were collected from Hefei Environmental Monitoring Center Station.Daily meteorological data(including average temperature,relative humidity)were obtained from China Meteorological Data Sharing Service System(http://cdc.nmic.cn/home.do).2.The time series of cardiovascular diseases and air pollutants were established.With controlling the confounding effects of long term trends,seasonality,day of the week,public holiday and meteorological factors(average temperature and average relative humidity,the distributional lag non-linear model(DLNM)were used to analyze several purposes,which were as following:(1)Quantitative analysis of the relationship between air pollutants and cardiovascular diseases deaths and the lag effects of air pollutants;(2)The study divided the whole year into four seasons of spring,summer,autumn and winter,and analyzed the differences between the air pollutants and the death of cardiovascular diseases in different seasons;(3)To analyze the differences of the relationship between air pollutants and cardiovascular diseases death in different subgroups by sex,age and educational level,and to explore the sensitive groups;(4)To analyze the impact of air pollutants on different types of cardiovascular diseases death.Results 1.The number of cardiovascular disease deaths of residents in Hefei city showed an increasing trend during 2007-2016.And this trend showed a certain seasonal,with more deaths in winter,less in summer.During the study period,the total number of cardiovascular deaths of residents was 34,500,and the daily average number of deaths of cardiovascular diseases was 9.44(range: 0-27).When cardiovascular deaths were stratified by sex,men were higher than women,with a ratio of 1.19:1(18774:15726).According to age stratification,deaths among residents aged < 65 were significantly lower than those aged > 65,and the ratio was 1: 5.6(5222: 29278).According to the level of education,there were more deaths from cardiovascular diseases than those with low levels of education,and the ratio was 4: 1(10474: 2633).2.During the study period,the air pollutants of PM10,SO2 and PM2.5 showed a declining trend year by year,while NO2,CO and O3 showed an upward trend.According to the national average daily air quality standards concentration limits in the “ambient air quality standards"(GB 3095-2012),the main pollutants were PM10 and PM2.5,followed by NO2.The daily average concentration of PM10,SO2,NO2,PM2.5,CO and O3 were(106.11±54.28)?g/m3,(20.34±12.64)?g/m3?(30.49±13.63)?g/m3,(72.59±46.15)?g/m3,(958.7±380.7)?g/m3 and(67.88±38.57)?g/m3.The daily average temperature and daily average relative humidity of Hefei city from 2007 to 2016 were(16.73 ± 9.46)°C and(74.43 ± 14.31)%,respectively.3.During the study period,there was a linear and threshold-free relationship between the air pollutants and cardiovascular diseases deaths.As the concentration of pollutants increased,the risk of death caused by cardiovascular diseases also increased.In the single-pollutant model,the daily average concentration of PM10,SO2,NO2,PM2.5,CO and O3 increased by one IQR(the IQRs of the air pollutants were 64.4 ?g/m3,14.32 ?g/m3,15.8 ?g/m3,46.23 ?g/m3,400 ?g/m3,and 50.05 ?g/m3),the greatest risk of deaths from cardiovascular disease were 1.64%(95%CI: 0.46%-2.83%),1.45%(95%CI: 0.72%~2.18%),1.04%(95%CI: 0.27%~1.55%),0.84%(95%CI: 0.04%~1.65%),1.66%(95%CI: 0.04%~3.31%),1.83%(95%CI: 0.51%~3.18%).When the multi-day lag cumulative effects were the maximum,the risk of cardiovascular diseases deaths increased by 4.34%(95% CI: 1.54%-7.23%),5.79%(95%CI: 2.43%~9.27%),4.47%(95%CI: 1.64%~7.37%),3.14%(95%CI: 0.03%~6.36%),3.11%(95%CI: 0.21%~6.10%),8.17%(95%CI: 1.89%~14.84%).In the multi-pollutant model,the single-day lagged effect values and the multi-day lagged cumulative effect values of air pollutants were both lower than the single pollutant model,and only the effects of SO2 and O3 on cardiovascular diseases death were relatively stable(P < 0.05).4.There were seasonal differences in the effects of air pollutants on cardiovascular diseases deaths.The effects of PM10,SO2,NO2 and CO in spring(March-May)was significantly higher than that in summer,autumn and winter(June-February),while the effects of O3 in winter season was higher.After stratified by season,PM2.5 had no significant effect on cardiovascular diseases deaths in all seasons(P > 0.05).5.The impact of gender,age and educational level on the relationship between air pollutants and deaths from cardiovascular diseases.Females and residents with low level of education were more sensitive to the impact of air pollutants.In age stratification,the residents aged 65 years and older were more sensitive to PM10,CO and O3,the residents under the age of 65 years old were more sensitive to SO2,NO2 and PM2.5.6.Air pollutants had different effect on the deaths of different types of cardiovascular diseases.According to the causes of heart disease,ischemic disease and cerebrovascular disease,the relationships between the deaths of various subgroups and air pollutants were different.Among them,heart disease was more sensitive to SO2 and O3,ischemic disease was more sensitive to O3,and cerebrovascular disease was more sensitive to PM10,SO2 and NO2.Conclusions 1.The deaths toll of cardiovascular disease in Hefei from 2007 to 2016 increased year by year,with more deaths in winter.2.The main pollutants that exceeded the standards in Hefei during the study were PM10 and PM2.5,followed by SO2.3.As the concentration of air pollutants increased,the risk of deaths from cardiovascular diseases also increased,and the relationship between the two was linear without threshold.SO2 was the main pollutant affecting the death of residents with cardiovascular diseases.4.There are seasonal differences in the effects of air pollutants on deatha of cardiovascular disease,the effects of PM10 SO2,NO2,CO were significantly higher than that in other seasons,while the effects of O3 in winter season was higher.5.Gender,age and educational level had impact on the relationship between air pollutants and deaths of cardiovascular diseases.In addition,the impact of air pollutants on the deaths of different types of cardiovascular diseases was also different.The results of this study suggest that when formulating local environmental and social policies,relevant departments should considered that the relevant modifying factors(Such as gender,age,educational level,type of cardiovascular disease,etc)have an impact on the relationship between air pollutants and deaths from cardiovascular disease. |
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