Preliminary Establishment Of Air Quality And Health Index Based On Exposure Response Relationship Of Air Pollution And Years Of Life Lost

Objective:1.To describe the distribution characteristics and time trends of the ambient pollutants（fine particulate matter[PM2.5],inhalable particles[PM10],sulfur dioxide[SO2],nitrogen dioxide[NO2],carbon monoxide[CO]and ozone[O3]）,meteorological data（daily temperature and relative humidity）,polulation death and years of life lost（YLL）.2.To build the exposure response function models for evaluating quantitatively the associations between the exposures to concentration of ambient pollutants and the burdens of disease（including cause-specific daily deaths and daily YLL）in Tianjin.3.To build the main components of ambient pollutants in Tianjin,then build the exposure response function models for evaluating quantitatively the associations between the main components of atmospheric pollutants and daily YLL,and construct the Air Quality Health Index（AQHI）for Tianjin.Finally,verify the rationality and applicability of the established AQHI.Method:1.We collected the daily average concentrations of six major air pollutants(PM_2.5,PM₁₀,SO₂,NO₂,CO and O₃),meteorological data（temperature and relative humidity）,the death data of each disease and the demographic data in Tianjin during 2014²017.2.We analyzed the annual average concentrations and characteristics of the main air pollutants,meteorological data,data of death and YLL in Tianjin during 2014²017using descriptive statistical analysis,and then we analyzed the annual trends using MK trend test analysis.We used Pearson correlation analysis to analyze the correlations between atmospheric pollutant concentrations and meteorological factors.Finally,we performed signed rank sum test to compare the daily total death of people in different genders and ages,and performed paired design t test on the daily total YLL of people in different genders and ages.3.We used the generalized additive model（GAM）,by adjusting for the confounders including long-term time trend,seasons,meteorological factors and others to build the exposure response function model between the three air pollutants and the daily mortality and YLL for the quantitative evaluation.Then we explored the effects of different lag days and moving days.Results were presented as changes of excess rate（ER）for death and YLL respectively for every 1μg/m3increase in atmospheric pollutants.4.We used principal component analysis to construct the main components of atmospheric pollutants in Tianjin.The AQHI in Tianjin was finally constructed by using the GAM to bulid the relationship between the main components of atmospheric pollutants and the daily YLL.5.We used the K-fold cross-validation method to verify the rationality of the AQHI model.And we evaluated the applicability of AQHI by comparing AQHI with AQI.Result:1.From 2014 to 2017,the annual average concentration of ambient pollutants in Tianjin showed a downward trend,except for an overall upward trend in O₃（P<0.001）.The average annual minimum temperature showed a trend of decreasement（P<0.001）.In addition to O₃,there were significant positive correlations between the concentrations of other atmospheric pollutants（P<0.01）.There was a positive correlation between the concentration of O₃ and temperature（P<0.001）,and a negative correlation with humidity（P<0.001）.For the health effects of the population,there was a statistically significant difference in total mortality and total YLL between different genders and ages（P<0.001）.And the difference in total mortality and YLL between the six districts in Tianjin was statistically significant（P<0.01）.2.There are lag periods in the exposure response relationship between ambient pollutants and daily population mortality and daily YLL.According to the exposure response relationship between the pollutants and health effects,we selected the 0¹moving average concentration of PM₁₀,PM_2.5,SO₂ and NO₂,the 0³ moving average concentration of CO and the 0² moving average concentration of O₃.After that,we used principal component analysis on the above ambient pollutants and built two main components of atmospheric pollution in Tianjin,named F₁ and F₂.We used GAM to build the exposure response relationship function,it was found that with each increase unit of F₁,the total daily mortality risk increased by 0.9662%,and the total daily YLL increased by 18.420 person-years.With each increase unit of F₂,the total daily death risk increased by 1.1216%,and the total daily YLL increased by 22.409 person-years.3.The K-fold cross-validation results showed that the correlation between the predicted and actual values of total mortality and total YLL of AQHI was 0.742（P<0.001）and0.700（P<0.001）,respectively.Two correlation coefficients were more than 0.7,so the AQHI model was reasonable.The Chi square test was performed to compare the excellent rate of air quality assessment between AQI and AQHI.The difference was statistically significant（χ²=103.15,P<0.001）.There was a correlation between AQHI and AQI（r=0.807,P<0.01）,and the grading was also correlated（r_s=0.580,P<0.01）.With an increase of IQR for AQHI,the risk of daily mortality increased by 1.6924%（95%CI:0.7457%,2.6480%）,while for the AQI,the risk of daily mortality increased by 1.1489%（95%CI:0.3309%,1.9736%）.With an increase of IQR for AQHI,the risk of daily YLL increased by 32.797（95%CI:14.559,51.034）,while for the AQI,the risk of daily YLL increased by 22.367（95%CI:6.619,38.116）,which was less than AQHI.Conclusion:1.There are different lag periods for the exposure response relationship between ambient pollutants and total daily mortality and daily YLL in Tianjin.The main components of atmospheric pollutants in Tianjin comprehensively reflect the lag period and collinearity of various ambient pollutants.2.The Tianjin AQHI built in this study has a good application foreground.Firstly,the K-fold cross-validation method confirms that the AQHI has a good fit and reliability.Secondly,AQHI is superior to AQI in predicting total daily mortality and daily YLL.Therefore,AQHI in Tianjin comprehensively considers the impact of ambient pollutants on mortality and YLL.AQHI can comprehensively reflect the air quality.The promotion and application of AQHI has the important theory value and the significant practical significance.