Study On The Relationship Between Absolute Humidity And Mortality From Cardiovascular And Respiratory Diseases In Guangzhou

The problem of global climate change has become more and more prominent,and the study of the adverse effects of climate change on the health of the population has therefore become more and more urgent.Cardiovascular diseases(CVD)and respiratory diseases(RESP)are two major non-accidental causes of mortality and how they are affected by meteorological factors and air pollution factors has become a hot research topic in recent years.Previous studies mostly used temperature and relative humidity to study their effects on respiratory diseases,while the study of relative humidity seldom considered the actual water content in the air,so the absolute humidity(AH)was used to study its effects on cardiovascular and respiratory diseases.Under the condition of controlling the confounding influence of air pollution factors and non-major meteorological factors,the attributable burden of absolute humidity on cardiovascular diseases and respiratory diseases was estimated,so as to provide reference for environmental health policy and basis for prevention and protection work.The daily mortality data of CVD and RESP in Guangzhou on February 1,2013 to December 31,2018 were obtained from Guangzhou center for disease control and prevention(CDC).The meteorological data and air pollution data of the same period were obtained from the China Meteorological Data Sharing Service System and the China's National City Air Quality real-time publishing platform,respectively.Spearman rank correlation was used to analyze the degree of correlation between daily mortality of CVD,RESP and meteorological factors in Guangzhou.Distributed lag nonlinear model(DLNM)was used to analyze the relationship between CVD?RESP mortality and absolute humidity with a 35-day lag in Guangzhou population and the effects of absolute humidity on influenza and pneumonia(I?P)and chronic lower respiratory diseases(CLRD)were further analyzed.Then the stratified analysis was conducted according to gender.The degree of freedom for controlling the temporal trends,other meteorological factors,air pollution factors and the lag time of the model after including temperature for sensitivity analysis.Finally,the results of the absolute humidity model are compared with those of the temperature model.In total,110,282 cases of CVD mortality and 42,440 cases of RESP mortality in Guangzhou from February 1,2013 to December 31,2018,including 17,116 cases of I?P,and 19,926 cases of CLRD.CVD mortality was negatively correlated with absolute humidity,temperature,relative humidity,and precipitation,and positively correlated with atmospheric pressure and wind speed.Overall RESP mortality was negatively correlated with absolute humidity,temperature and precipitation,positively correlated with atmospheric pressure,but not significantly correlated with relative humidity and wind speed.I?P mortality were negatively correlated with absolute humidity and temperature,positively correlated with wind speed,but not significantly correlated with relative humidity,precipitation and atmospheric pressure.CLRD mortality was negatively correlated with absolute humidity,temperature and precipitation,and positively correlated with atmospheric pressure,but not with relative humidity and wind speed.The attributable burden of mortality due to absolute humidity for CVD was 14.68%(95%CI: 11.09%?18.05%).The attributable burden of mortality due to absolute humidity for RESP,I?P,and CLRD were 21.57%(95%CI:14.20%?27.75%),21.88%(95%CI: 10.35%?29.45%)and 23.41%(95%CI:11.62%?33.13%),respectively.The attributable burden of mortality from CVD,RESP,I?P caused by high absolute humidity is greater than that caused by low absolute humidity.For CLRD,lower absolute humidity contributes more to the attributable burden of mortality.Absolute humidity did not significantly differ in the attributable risk of CVD and RESP between age group and sex,but the number of attributed mortality was larger in the elderly.In addition,the number of attributed mortality from RESP in males was significantly higher than that in females(5501 males and 3652 females).The sensitivity analysis showed that the results of the model were stable after adjusting the parameters.By comparison,the absolute humidity model resulted in a slightly higher attributable burden for CVD and RESP mortality than the temperature model.This study explored the relationship between absolute humidity and mortality from cardiovascular and respiratory diseases by constructing a distributed lag nonlinear model and controlling for other meteorological factors and air pollution.The results suggest that high or low absolute humidity may increase the risk of mortality from respiratory diseases in older adults.Absolute humidity may be a more sensitive exposure indicator than temperature to examine the burden of mortality from CVD and RESP.The conclusion of this study can provide reference for the formulation of environmental health policy and theoretical basis for the prevention and protection of public health departments.