The Impact Of Extreme Temperature On Health Risk In The Major Cities In Northeast China

In recent years,average temperature rises obviously with the global warming,and the frequencies of extreme weather and climate events increase.Numerous studies have proved that temperature is the most important meteorological factor that affect human health.Therefore,studying the impact of extreme temperature on health is of great significance.In this study,we used pollutant data and mortality data of respiratory diseases,cardiovascular diseases and non-accidental death from 1st,2014 to December31 st,2016,and meteorological data from daily observation stations from 1989 to 2019.We respectively defined extreme high temperatures as the temperatures when the average daily temperature of 1989 to 2019 exceeded the percentiles(P90,P92.5,P95,P97.5,P99),and extreme low temperatures as the average temperature below the percentiles(P1,P2.5,P5,P7.5,P10).The event that the extreme high/low temperature occurs continuously for more than 2,3,4 days was defined as heat wave and cold spell.We selected extreme weather according to different extreme threshold definitions,a model combining Distributed Lag Non-linear Model(DLNM)and Generalized Linear Model(GLM)was used to study the single-day lag effect and cumulative lag effect of extreme temperature on death.For heat wave and cold wave events,we analyzed the main effects caused by the temperature during the heat wave and cold spell and the additional effects caused by the time lasted for.By calculating the QAIC value,the definition of the heat wave and cold spell events corresponding to the optimal model is obtained,and the definitions of the heat wave and cold wave events are selected accordingly.According to the definition,we screened out a typical heat wave and cold wave events and conducted a case analysis:(1)By analyzing the single-day lag effect of average daily temperature on the number of deaths,the average temperature has the most significant effect on the death of respiratory diseases,and obvious peaks can be found in both high and low temperature areas.The heat effect changed more rapidly and intensely(3-5 days),while the cold effect increases slowly,and the lag time is longer(14 days).Regarding the cumulative lag effect,the high temperature is strongest at lag 2 day,and the low temperature increases after the lag 7 day.Among the three causes of death,the number of deaths from respiratory diseases is most significantly affected by extreme temperatures.(2)Analyzing the results of cold days(nights)and warm days(nights)on the number of deaths from diseases,it can be seen that the influence of warm days in Shenyang is the strongest,and the RR value is 1.045(95%CI: 1.023-1.067).And deaths from respiratory diseases are most affected by warm nights,with an RR value of 1.050(95%CI: 1.022-1.077).The comparison results show that the impact of warm nights and warm days on Shenyang,Changchun and Harbin is higher than that of cold nights and cold days.(3)Comparing the main effects of heat waves on the three kinds of deaths,it can be found that heat waves have the most obvious impact on respiratory moratily,and the lag time is longer(above 5 days),while the impact on deaths from nonaccidental and circulatory diseases is less and has a shorter lag time(3 days).The additional effect of the heat wave increased with the increase in the number of days and the threshold temperature.Comparing the three regions,the additional effect of heat waves on human deaths decreases with increasing latitude,and Shenyang is significantly higher than Changchun and Harbin.The cold spell(the threshold is P1,and the temperature is-18.4°C,-21.3°C,-23.7°C)has the largest main effect on the three cities.For circulatory mortality,the risk of death for females(1.400(95%CI:1.129-1.735))was greater than that for males(1.222(95%CI: 1.137-1.314));for respiratory mortaltiy,the risk of death for males(1.545(95%CI: 1.066-2.239))was greater than that for females(1.344(95%CI: 1.100-1.641)).The additional effect of the cold spell on the death population,the risk of males was slightly greater than that of females.(4)According to the QAIC value,we found that for non-accidental deaths and deaths from circulatory system diseases,the optimal thresholds for heat waves are lower and the thresholds for cold waves are higher;for deaths from respiratory diseases,the optimal threshold for heat waves is higher,and the optimal threshold for cold waves is lower.