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[背景]虽然人们已经对PM2.5的质量与死亡率之间的关联进行了广泛研究,但很少有国家级的分析来评估PM2.5的化学成分对死亡率的影响。流行病学研究认为,PM2.5对死亡率的预估影响存在空间和季节性变化。我们推测,如果PM2.5的成分变化导致PM2.5对死亡率估值的影响产生变化,则PM2.5成分与死亡率之间关联不会随空间或季节变化。[目的]提供首个国家级、具有季节特异性和区域特异性的死亡率与PM2.5成分之间关联的研究报告。[方法]评估2000—2005年间,美国72个城市社区中,非意外死亡率与PM2.5成分之间的短期关联。采用美国环境保护署(EPA)化学形态监测网的数据,对PM2.5的7种成分进行分析,包括:有机碳物质(OCM)、元素碳(EC)、硅、钠离子、硝酸盐、铵和硫酸盐,这7种成分共占PM2.5质量的79%~85%。采用时间序列泊松回归模型,控制时间和天气因素,评估它们对死亡率的影响。[结果]单一污染物模型显示,OCM、EC、硅和钠离子的四分位数间距增加,分别与死亡率增加0.39%[95%后验区间(PI):0.08~0.70]、0.22%(95%PI:0.00~0.44)、0.17%(95%PI:0.03~0.30)和0.16%(95%PI:0.00~0.32)相关联。未发现证据表明死亡率与PM2.5或PM2.5成分之间的关联存在季节或地区性变化。[结论]本研究结果表明,某些PM2.5的成分可能比其它成分具有更强的毒性,因此,单独调控PM的总质量可能并不足以保护人类的健康。
[Background] Although extensive research has been conducted on the association between PM2.5 mass and mortality, there are few national-level analyzes to assess the impact of the chemical composition of PM2.5 on mortality. Epidemiological studies suggest that there are spatial and seasonal variations in the estimated impact of PM 2.5 on mortality. We hypothesize that if changes in PM2.5 composition lead to changes in the impact of PM2.5 on mortality estimates, the association between PM2.5 components and mortality does not change with space or season. [Objective] To provide the first national-level study of the association between seasonal and sex-specific mortality and PM2.5 components. [Method] To evaluate the short-term correlation between non-accidental mortality and PM2.5 in the 72 urban communities in the United States from 2000 to 2005. The seven components of PM2.5 were analyzed using data from the U.S. Environmental Protection Agency (EPA) Chemical Morphology Monitoring Network, including: organic carbon (OCM), elemental carbon (EC), silicon, sodium, nitrate, And sulphate, which together account for 79% to 85% of the PM2.5 mass. A time-series Poisson regression model was used to control time and weather factors and assess their impact on mortality. [Results] The single pollutant model showed that the interquartile range of OCM, EC, silicon and sodium increased with the increase of mortality by 0.39% [95%, PI: 0.08-0.70] and 0.22% 95% PI: 0.00 to 0.44), 0.17% (95% PI: 0.03-0.30) and 0.16% (95% PI: 0.00-0.32). No evidence was found that there was a seasonal or regional variation in the association between mortality and PM2.5 or PM2.5 components. [Conclusion] The results of this study indicate that some PM2.5 components may be more toxic than other components. Therefore, the total mass of PM alone may not be sufficient to protect human health.