非适宜气温和PM_(2.5)及其协同作用对不同年龄段老年人死亡的影响

Influence of synergies between non-optimal temperature and PM_(2.5) on mortality of older people of different ages

老年人群是脆弱群体的主体,非适宜气温和PM_(2.5)对不同年龄段老年人的危险性、滞后期、收获效应、协同作用可能存在相关规律,但是尚缺乏非适宜气温和PM_(2.5)对细分年龄段老年人的影响研究。本研究以中国老龄化最严重的江苏省南通市为例,收集了2012—2017年256037位65—104岁死亡者信息,并按年龄分为6组,运用广义相加模型和分布滞后非线性模型分别研究了非适宜气温、PM_(2.5)对各组人群的相对危险度、死亡归因分值和滞后期,以及二者的协同作用。结果显示:(1)随年龄增长,非适宜气温的相对危险度和归因分值不断升高,并且低温升高的幅度远高于高温,在90岁以上组分别达到高温的1.46和6.49倍,PM_(2.5)的相对危险度先降低后升高,高龄老人的主要危险因素是低温。(2)低温、高温分别具有9—12和3—6 d的滞后期,但是滞后期与年龄无关;PM_(2.5)的滞后期随年龄增长而延长。(3)仅在78岁以下观察到高温的收获效应,说明高温对78岁以上高龄老人的影响并不局限于身体脆弱者和患病者。(4)非适宜气温和PM_(2.5)存在协同作用,死亡人数随气温降低、升高、PM_(2.5)浓度升高而增多,但不同年龄的变化幅度有差异。研究结果可为制定老年人群在各个年龄对大气环境中的危险因素应对策略提供参考,但由于南通是老龄化最严重的地区,未来还需在其他地区做进一步的研究,增加结论的适用性。

Older people are the main representative of vulnerable groups.Age-related laws of the risk,lag period,harvest effect and synergistic effect of non-optimal temperature and PM_(2.5) on older people of different ages are not very clear.This study collects the information of 256037 mortality aged 65—104 from 2012 to 2017 in Nantong district,Jiangsu province,where aging rate is the highest in China.The mortality data are divided into 6 groups by age.The Generalized Additive Models(GAM)and Distributed Lag Non-linear Model(DLNM)are adopted to explore the adverse health effects(relative risk,attributable fraction and lag effect)of temperature,PM_(2.5) and their synergistic effects on all-cause mortality.The results are as follows:(1)The relative risk and attributable fraction of non-optimal temperature increase continuously with increasing age.Low temperature effect is much more remarkable than that of high temperature.The relative risk and attributable fraction of low temperature are 1.46 and 6.49 times higher than that of high temperature for the group of over 90 years old,respectively.The relative risk and attributable fraction of PM_(2.5) first decrease and then increased with increasing age.The main risk factor for the oldest population is low temperature.(2)Effects of low temperature and high temperature have a lag period of 9—12 d and 3—6 d,respectively,but the lag period is irrelevant to age.The lag period of PM_(2.5) increases with age.(3)Harvest effect of high temperature is observed in groups under the age of 78,indicating that the effect of high temperature on the population of 78 years and older is not limited to the vulnerable group and is not dependent on illness.(4)Effects of synergies between non-optimal temperature and PM_(2.5) reveal that mortality increases with higher and lower temperature and PM_(2.5),but the range fluctuates with age.Low temperature is more dangerous than high temperature and high PM_(2.5).These results provide a reference for establishing strategies to handle risk factors of the atmospheric environment for the population of different ages.However,note that the conclusion is not universal because this study is limited to the situation in Nantong.