【作者】 高翔；

【导师】 陈立民；

【作者基本信息】 复旦大学 ， 环境科学， 2008， 博士

【摘要】 固体生物质燃料燃烧导致的室内空气污染被认为是引发和加剧发展中国家人群呼吸系统疾病、心脑血管系统疾病等的一个重要因素。我国西藏地区由于发展程度相对落后,人群的空气污染暴露模式与其他地方相比,具有特殊性和典型性。然而之前对于西藏地区燃烧源室内空气污染的研究尚未见报道,这就阻碍了对该地区居民的环境健康影响研究和相关政策的制定与执行。为了解西藏农牧区居民污染暴露模式,评估燃烧源污染对人群污染暴露的贡献,评价其对人群健康的影响,并分析采取不同干预措施可获得的健康和经济效益,本文采取将实地污染监测、实验室模拟燃烧实验、健康与政策分析相结合的方法,研究了牛粪饼的燃烧特征,并在西藏农区的曲水、扎囊、江孜县和牧区的当雄县进行了污染监测,开展了农牧民人群活动的时空特征与农牧区家庭能源结构调查,对西藏农牧区民居室内空气污染特征进行了分析,并提出相应的控制措施。研究表明,西藏农牧区人群因室内牛粪饼燃烧造成的污染暴露占到居民细颗粒物暴露总量的47.0%到99.7%,是西藏农牧区人群主要的污染暴露源。牛粪饼是西藏典型的固体生物质燃料,与秸秆类和木质类生物质燃料相比,其灰分含量高、热值低,这导致西藏居民在进行炊事等活动时必须使用更大的燃料量,导致室内污染的增加。本研究认为,保障燃烧供气、加强炉具保温、提高排烟效率、改变人群活动的空间特征等有利于降低室内污染浓度和人群污染暴露水平,减低人群健康风险。在西藏农村进行的室内污染监测表明其室内空气污染问题严重。农牧区燃烧活动所在空间的室内PM₁₀日均浓度均超过我国室内空气质量标准,超标倍数为1.1～28.8倍。室内颗粒物污染因生物质燃料类型和炉具类型的不同,而具有很大差异。其中采用火塘为炉具的室内颗粒物污染最严重,PM_2.5浓度达到1448.74μg/m³,是使用铸铁炉的12.6倍。室内颗粒物质量浓度高峰出现在0.65-1.1μm粒径段和＞9.0μm粒径段。颗粒物中水溶性无机组分以Cl、K、Ca为主,Cu、Fe、Mn、Zn含量较低,而As、Cr、Ni等其他重金属元素未检出。颗粒态PAHs总量呈单峰分布,主要聚集在粒径2.1μm及以下的颗粒物上,其主要来源是作为燃料的牛粪饼的燃烧;生成PAHs的特征谱与其他生物质燃料、化石燃料的燃烧有明显不同。其中BaP和BbkF等毒性当量系数大的几种化合物含量高,BaP浓度超过我国国家标准的80倍。西藏农村室内当前水平的PAHs浓度致癌风险为6.41×10^-3,具有较高的危险性。室内CO日均浓度水平低于国家限定标准,但炊事时段的污染高峰有害于火源地附近人群的健康。在西藏农牧区实施炉具改良、空间分割和能源更新的干预措施,可以不同程度减少居民的污染暴露。在农区实施农牧民安居工程带来的厨房和卧室空间分离,可以使区域内人群长期死亡率下降近20%,减少慢性支气管炎、急性支气管炎和成人哮喘发病20%左右;而在此基础上进一步实施农村沼气工程,则可使上述健康改善效果达到25%至30%。对仍处于长年游牧的人群采用炉具改良的干预措施,可以使当地人群的急性呼吸系统感染和急性下呼吸道感染发病下降40%以上;而如果实施安居工程,让这一人群在秋冬春三季定居,则可以使上述健康改善的效果分别达到80%和60%左右。在牧区为已经定居的牧民进一步实施安居工程改善其居住环境,可以减少人群的呼吸系统住院、心血管系统住院、成人哮喘发病、急慢性支气管炎发病5%至15%左右,对人群长期死亡率的减低效果为13%。在全西藏实施上述干预措施,每年至少可为居民节省医疗费用开支1200万元。此外,针对非游牧人群实施空间分割干预措施后,因人群健康状况改善对社会产生的经济贡献将达到4.19亿元;在此基础上再实施能源更新措施的经济贡献总共将达到5.42亿元;分别相当于西藏2004年全区GDP的1.98%和2.56%。更多还原

【Abstract】 Indoor air pollution caused by domestic use of solid biomass fuels （SBFs） has strong associations with pulmonary and cardiovascular diseases. In Tibet China, as the development is relatively slow, the pollution exposure pattern of the residents is unique and typical. However, studies on indoor air pollution in Tibet and its health effects are inadequate.In order to discover the pollution exposure sources, assess the contribution of combustion to public pollution exposure, estimate the health effects and social-economic effects of pollution exposure interventions, this study focused on the pollution characteristics caused by cow dung cake combustion, the indoor air pollution in the agricultural and pasturing areas in Tibet, and the public particulate matter （PM） exposure in rural Tibet. Result shows that indoor dung cake combustion is the dominant factor to the pollution exposure of rural residents in Tibet, which contributes at 47.0% to 99.7% to total PM exposure.The fuel parameter and composition test showed that the ash content of dung cake was higher while the heating value was lower than common SBFs such as agricultural straw and wood. These asked more consumption of dung cake for everyday use than other fuels, which would cause heavier indoor pollution. Research also showed that the contents of trace metal elements were low which indicated the low potential of trace elements toxicity to the residents. To increase the air supply and to minish the fuel size would make a better mix of oxygen and dung, and this would increase combustion efficiency and reduce CO emission. The PM emission from dung cake combustion was dominant by the sub-micron particles, especially those with aerodynamics diameter of 0.03-0.40μm.Field monitoring was carried out in both the agricultural （in Qushui, Zhanang, and Jiangzi Countries） and pasturing （in Dangxiong Country） areas of Tibet, while questionnaire survey was also performed. Sampling was taken in kitchens, bedrooms, living-rooms, tents, and the outdoor environment. The result showed that the daily average indoor CO pollution from dung cake combustion was under control, however, the peak concentration during cooking time was high enough to cause adverse health effects to the population involved in cooking. The size distribution showed the high comcentration of indoor PM appeared at diameters of 0.65-1.1μm and >9.0μm. Daily average PM₁₀ concentration exceeded the national standard of 0.15mg/m³ at1.1 to 28.8 times. The indoor PM₁₀ concentration in the tents with dung cake burning as open fire was as high as 3.02mg/m³, which is 12.6 times to those used stoves with chimney in the tents.Inorganic component analysis of indoor PM showed that the water soluble content was dominant by Cl, K, and Ca, while there was a low concentration of Cu, Fe, Mn, and Zn, and elements like As, Cr, Ni and other heavy metals were under detection limit. Organic component analysis showed the indoor polycyclic aromatic hydrocarbons （PAHs） were at a high risk. It was found that the PAHs were concentrated in PM with diameter less than 2.1μm. The primary source of the indoor PAHs was the combustion of dung cake. Among the detected PAHs, compounds with high cancer risk, such as BaP and BbkF, showed high concentration, for example, the concentration of BaP exceeded the national standard for 80 times. The total cancer risk of Tibetan indoor PM was 6.41×10^-3, which indicated the environmental health status was serious.If the improved stoves were equiped to those tent used throughourthe year, the morbidity of acute respiratory infections （ARI） and acute lower respiratory infections （ALRI） would reduce to about 60%. For people who live in tent only in summer in the pasturing area, to separate kitchens from living area would reduce the long-term mortality, chronic bronchitis, acute bronchitis, and asthma attack by 5% to more than 15%. For people live in the agricultural area, these interventions would result in more than 20% reduction of the health endpoint above by separating rooms, and more than 25% by methane use. And these would save the medical cost by more than 12 million yuan/year for the whole population in Tibet. The improvement of health would also contribute to the increase of local GDP at 419 million yuan/year for separating rooms, and at 542 million yuan/year for methane use, which equals to 1.98% and 2.56% of the Tibetan local GDP respectively.更多还原