近年来我国多地发生严重雾霾天气,空气动力学直径在2.5微米以下的颗粒物(PM2.5)被认为是大气污染的罪魁祸首。但粒径更小颗粒物的健康危害如何,目前尚无定论。近日,复旦大学公共卫生学院、上海市大气颗粒物污染防治重点实验室阚海东教授课题组研究证实:粒径小于0.5微米的大气颗粒物对人体健康危害更大,且粒径越小,危害越大。
相关论文已发表于公共卫生领域权威期刊《环境健康展望》(Environmental Health Perspectives)。论文第一作者孟夏介绍,课题组在我国某城市测量了0.25~10微米(即PM0.25~PM10)范围内23组不同粒径的颗粒物数量浓度,分析和比较了它们与居民健康风险的关系。结果显示,粒径在0.25~0.50微米范围内的颗粒物数浓度与居民健康危害,尤其是心血管疾病风险的关系最为显著,而粒径大于0.50微米的颗粒物数浓度与居民健康风险没有显著关联。
课题组推测,颗粒物的粒径越小,其对应的数量浓度和总表面积越大,越有可能吸附更多的有害物质进入人体;也有可能与不同粒径的颗粒物在下呼吸道的沉降方式有关,粒径小于0.50微米的颗粒物主要以扩散方式沉积,而大于0.50微米的颗粒物主要以撞击方式沉积。(生物谷Bioon.com)
生物谷推荐的英文摘要
Environmental Health Perspectives doi.org/10.1289/ehp.1103671
Fine Particulate Matter Constituents and Cardiopulmonary Mortality in a Heavily Polluted Chinese City
Junji Cao1, Hongmei Xu1, Qun Xu2, Bingheng Chen3, Haidong Kan3,4
Background: Although ambient fine particulate matter (PM2.5; particulate matter ≤ 2.5 μm in aerodynamic diameter) has been linked to adverse human health effects, the chemical constituents that cause harm are unknown. To our knowledge, the health effects of PM2.5 constituents have not been reported for a developing country.
Objectives: We examined the short-term association between PM2.5 constituents and daily mortality in Xi’an, a heavily polluted Chinese city.
Methods: We obtained daily mortality data and daily concentrations of PM2.5, organic carbon (OC), elemental carbon (EC), and 10 water-soluble ions for 1 January 2004 through 31 December 2008. We also measured concentrations of fifteen elements 1 January 2006 through 31 December 2008. We analyzed the data using overdispersed generalized linear Poisson models.
Results: During the study period, the mean daily average concentration of PM2.5 in Xi’an was 182.2 μg/m3. Major contributors to PM2.5 mass included OC, EC, sulfate, nitrate, and ammonium. After adjustment for PM2.5 mass, we found significant positive associations of total, cardiovascular, or respiratory mortality with OC, EC, ammonium, nitrate, chlorine ion, chlorine, and nickel for at least one lag period. Nitrate demonstrated stronger associations with total and cardiovascular mortality than PM2.5 mass. For a 1-day lag, interquartile range increases in PM2.5 mass and nitrate (114.9 and 15.4 μg/m3, respectively) were associated with 1.8% [95% confidence interval (CI): 0.8%, 2.8%] and 3.8% (95% CI: 1.7%, 5.9%) increases in total mortality.
Conclusions: Our findings suggest that PM2.5 constituents from the combustion of fossil fuel may have an appreciable influence on the health effects attributable to PM2.5 in Xi’an.