北京极端污染天气颗粒物物化表征及其对健康的影响

Air pollution has become an increasingly serious problem in China. To control the pollution level and determine its quantitative impact on human health has been listed as one of the most major tasks by the government. The capital, Beijing has been plagued by extreme air pollution weather conditions i.e. "spring dust storms" and "haze", which have serious threat on people's physical and mental health. Inhalable particulate matter (PM10) and fine particulate matter (PM2.5) are key factors affecting those extreme conditions, with typical sources including dry salt lake dust ('dust storm' source) and combustion sources such as fossil coal, biomass, gasoline and diesel ('haze' sources). This project aims to analyze physical and chemical characteristics of PM10 and PM2.5 emitted by various sources separately, so as to determine their toxicity and the relative concentration range. Methodologies include trachea injection to dye dust experiment on rat with PM10 and PM2.5 from different sources, observation of outdoor long-term chronic health effects on rat under composite air pollution with and without application of different protective measures and analysis of outdoor wild Milu carcasses. Then, animal damage mechanism of PM10 and PM2.5 from different sources will be interpreted based on animal morphology, behavior, pathology, etc. and finally dose - health effects model will be set up and the population health risk under extreme air pollution weather conditions will be predicted. It is expected that the project outcomes will help people to form objective and rational attitude towards air pollution, to avoid and mitigate its health effect scientifically and effectively, and to provide important and scientific basis to the government for extreme air pollution control.

我国大气污染问题日益严峻，对其治理以及定量确定它对人体健康的影响已经被政府列为首要解决的重大问题。首都北京不断受到极端大气污染天气"春季尘暴"和"雾霾"的困扰，严重威胁人群身心健康。可吸入颗粒物(PM10)和细微颗粒物(PM2.5)是构成北京极端大气污染天气的关键因素，其典型来源有干盐湖尘（'尘暴'源）和煤、生物质、汽柴油等燃烧源（雾霾源）。本项目旨在对各类污染来源排放PM10和PM2.5进行物化表征，确定各种污染颗粒物毒性和发生浓度范围，借助大白鼠气管注射染尘实验、采取不同防护方法的大气复合污染户外暴露健康影响观察、户外野生动物麋鹿尸体解析，从动物形态、行为、病理等方面阐释不同来源PM10和PM2.5的健康伤害机制，建立剂量-健康效应模型，预测北京市极端污染天气的人群健康风险，有助于客观理性看待污染、科学有效减轻、规避污染对健康影响、以及为极端大气污染治理提供重要的科学依据。

北京“沙尘暴”和“雾霾”严重危害健康，选交通带、商业区、乡村、郊区重污染天气采集颗粒物PM，采集污染源盐碱地地表扬尘和煤/汽油/柴油燃烧排放的PM，进行物化分析并对大鼠急性暴露；采集煤/汽油/柴油燃烧排放尾气物化分析、动态监测大气PM2.5浓度，并对小鼠亚慢性暴露；暴露后测定鼠肺氧化炎症因子、生理病理变化、细胞增长和凋亡，考察补给维生素B对损伤缓解的可能。结论：（1）对PM10贡献较大的沙尘暴后期的浮尘天、对PM2.5贡献较大的雾霾天微风和冬季低温静稳高湿时，PM更易富集化学污染物而危害健康，防治沙尘暴和雾霾重污染时更应受到关注。（2）PM污染对鼠肺和气管造成组织病理伤害，PM2.5伤害程度多大于PM10。沙尘暴天PM10和雾霾天PM2.5可显著降低大鼠免疫力，前者可显著提高TGF-β1。PM10中4-6环PAHs和PM2.5中Na+显著抑制人支气管上表皮细胞（HBE）增长；PM10中的萘、苯并（k）荧蒽和Ni，及PM2.5中的EC、苯并（a）蒽、䓛、苯并（b）荧蒽、苯并（a）芘使HBE细胞周期主要阻隔于G1期（有丝分裂完成后到复制开始前），且阻隔效应与PM浓度呈一定依赖性；PM10中的萘促细胞坏死和晚期凋亡、PM2.5 Cr促细胞早期凋亡。（3）不同污染源盐碱扬尘、煤/汽油/柴油燃烧排放的PM2.5急性染毒造成大鼠气管和肺组织明显炎症病变，升高特定的炎症因子和降低特定的氧化因子、诱导细胞凋亡，通过改变血常规参数参与免疫调节，其富含的化学物质类型是可能原因。煤/汽油/柴油燃烧排放气体的亚慢性暴露也造成小鼠肺炎症损伤且存在时间效应，升高特定的炎症因子和降低特定的氧化因子、提高细胞凋亡率且存在时间效应，与排放的高浓度污染气体和PM污染物有关。（4）服用高剂量维生素B不能缓解汽油燃烧亚慢性暴露对小鼠肺部的病理伤害。（5）亚慢性暴露于浓度超标的大气PM2.5显著降低雄鼠新陈代谢、肺组织出现炎症和增生；显著增加雌鼠肿瘤细胞和过氧化物产生可能。（5）雾霾天气明显降低雄黇鹿领地吼叫用时、提高母鹿发情用时和频次。