Assessment Of Regional Health Vulnerability To Extreme Heat In China

Backgrounds:With the climate warming,the impact of temperature on health is gradually increasing.Many studies have shown that high temperature would exacerbate the burden of disease and increase mortality.The health risk caused by high temperature depends on the interaction among exposure,sensitivity and adaptability of the population to high temperature.Due to the differences of population adaptability,socio-economic development level,geographical location and climatic conditions,the impact of extremely high temperature on human health is tend to be variant with regions.The damage of high temperature to human health can be prevented to a certain extent,so understanding the regional distribution of high temperature vulnerability and its influencing factors is conducive to the formulation and implementation of targeted protection strategies.Objectives:To construct the evaluation index system and evaluation model for health vulnerability of regional populations to extreme heat;To evaluate the regional health vulnerability to extreme heat and identify the characteristics of regional distribution and the main influencing factors of the health vulnerability to extreme heat in China,so that to provide scientific basis for formulating adaptive strategies,public health intervention measures and resource allocation plans against extreme heat.Methods:The data from 2014-2019 were collected including provincial statistical yearbook,statistical bulletin,China Environmental Statistics Yearbook,China Urban Statistical Yearbook,China Health Statistics Yearbook,meteorology,air quality and other data.After the appropriate evaluation indicators for health vulnerability of extreme heat were selected through literature review,correlation analysis among indicators and principal component analysis according to the principles of scientificity,comprehensiveness,representativeness and operability,the evaluation indicator system was developed from the three dimensions of exposure,sensitivity and adaptability.The mean value of the related indicators in 19 representative cities from 2014 to 2018 was calculated,and the principal components and their weights were determined by principal component analysis method to build a comprehensive assessment model of health vulnerability to extreme heat.The value of health vulnerability index of extreme heat for 19 representative cities was calculated by addition and subtraction method(vulnerability index=exposure index score+sensitivity index score-adaptability index score),and the 5-year average extreme heat health vulnerability of 19 representative cities was evaluated.The proportion of deaths on hot days in summer during the same period was taken as the health outcome,and the correlation analysis between the proportion of deaths and the vulnerability index was carried out to primarily verify the vulnerability assessment results.Finally,the vulnerability assessment data of 31 provinces(autonomous regions and municipalities)in 2019 were collected,and the extreme heat health vulnerability index of 31 provinces(autonomous regions and municipalities)in 2019 was calculated by using the comprehensive assessment model of health vulnerability to extreme heat that had been established using the data of 19 representative cities.Results:1、Construction of extremely high-temperature health vulnerability evaluation index systemA total of 88 relevant indicators for evaluation of vulnerability to extremely high temperature were selected through literature review and health risk assessment research.After removing 25 evaluation indexes that could not be obtained and deleting 22 evaluation indexes by correlation analysis,a total of 20 evaluation indexes were finally selected by principal component analysis,including meteorological,air quality,population,economy,living standards,social infrastructure construction,medical and health indicators,etc.The six exposure indicators included average annual temperature,number of days≥P95 of daily maximum temperature,frequency of heat wave,average annual relative humidity,PM2.5,NO2.Seven sensitivity indicators included the elderly population dependency ratio,the proportion of the low-income population,more than five people ratio,maternal mortality rate,perinatal mortality rate and incidence rate infectious disease.Seven adaptability indicators included per capita GDP,per capita health care spending,green coverage,air conditioning and other ownership per 100 households,domestic electricity consumption of urban residents,per capita daily domestic water consumption and amount of precipitation.2.Extreme heat-health vulnerability assessment in representative citiesAccording to the results of principal component analysis,four principal components were extracted from the study.The first principal component mainly represented health care(the main contribution indicators including the dependency ratio of the elderly,maternal mortality,perinatal mortality and incidence rate of infectious diseases,etc.);The second principal component mainly represented living environment(the main contribution indexes including more than 5 households,annual average temperature,etc.);The third principal component mainly represented social economy(the main contribution indicators including the proportion of the single population,per capita GDP,the consumption of electricity for urban residents,etc.);The fourth principal component mainly represented air quality(the main contribution indexes including PM2.5,NO2,etc.).The contribution rate of total variance of four principal components was 77%.The results showed that there were spatial distribution differences in health vulnerability to extreme heat.Among 19 representative cities,the city with the highest vulnerability index was korla(0.361),and the lowest was Beijing(-0.074).The highest exposure index was in Ningbo(0.161),and the lowest was in Hulunbuir(0.005).The highest sensitivity index was in korla(0.311),and Jinan City(-0.039)had the lowest sensitivity.The highest adaptive index was in Shenzhen(0.248),and that of Hulunbuir(0.035)was the lowest.3.Validation of the evaluation results of health vulnerability to extreme heat in representative citiesThe results of health vulnerability assessment of extremely high temperature in 19 representative cities showed that the correlation coefficient between the vulnerability indexes and the proportion of deaths on days with extremely high temperature in summer was 0.518(P=0.023).It was indicated that the evaluation of health vulnerability to extreme heat in 19 representative cities could reflect the comprehensive impacts of extreme heat on the health of the population in the study areas to a certain extent.The evaluation model of health vulnerability to extreme heat that had been constructed was relatively reliable,and the results could be used as the basis for subsequent expansion analysis.4.Evaluation of health vulnerability to extremely high temperature in 31 provinces(autonomous regions and municipalities directly under the Central Government)in ChinaThe top 5 of extreme high-temperature health vulnerability index were Tibet Autonomous Region(0.182),Qinghai Province(0.112),Tianjin City(0.076),Xinjiang Autonomous Region(0.075),and Shanxi Province(0.047).The top five of the extremely high-temperature health vulnerability index were Shandong Province(-0.082),Inner Mongolia Autonomous Region(-0.090),Sichuan Province(-0.097),Beijing(-0.100),and Jiangsu Province(-0.132).According to ArcGIS "natural breakpoint analysis",the vulnerability index was divided into five grades:the lowest,lower,medium,higher and the highest.It was shown that the lowest vulnerability areas mainly included Inner Mongolia,Beijing,Sichuan,Shandong,Jiangsu and Zhejiang;The lower vulnerable areas mainly included Heilongjiang,Jilin,Liaoning and Shanghai.The medium vulnerable areas mainly included Ningxia,Anhui,Hubei,Guizhou,Hunan,Jiangxi,Yunnan,Guangxi,Guangdong and central and southern of Fujian.The higher vulnerable areas mainly included Gansu,Shaanxi,Shanxi,Hebei,Henan,Chongqing and Hainan.The highest vulnerable areas mainly included Tibet,Qinghai,Xinjiang and Tianjin.Conclusions:The extreme heat-health vulnerability assessment index system and evaluation model was established with three dimensions of exposure,sensitivity and adaptability.The indicators that had great influence on regional health vulnerability included the health care level indicators(the elderly population dependency ratio,maternal mortality,perinatal child mortality,and incidence of infectious diseases),living environment indicators(5 households overpopulation,the annual average temperature),socio-economic level indicators(the proportion of people living alone,per capita GDP,urban residential electricity consumption),air quality(PM2.5,NO2),etc.The regional distribution of health vulnerability to extreme heat in China was quite different.The regions with high vulnerability were mainly concentrated in the western and central and eastern regions.The areas with low vulnerability were mainly concentrated in Inner Mongolia,northeast and central and eastern coastal areas.In the areas with high exposure and sensitivity,the vulnerability was relatively higher,while the adaptability level could reduce the vulnerability to a certain extent.The results of vulnerability assessment can effectively locate the high vulnerable areas to extreme heat,and provide scientific reference for the development of adaptive measures and resource allocation plans.