基于事故树方法的城市灰霾的致因机理分析:以天津市为例

Causation mechanism analysis of urban haze based on FTA method:taking Tianjin as a case study

近年来,以PM2.5为特征的灰霾天气已成为中国许多城市极其严重的环境污染问题,对大气质量和人体健康具有严重的不良影响。由于煤炭在我国能源结构中占据主导地位,燃煤废气可能是导致灰霾污染的其中一个非常关键的影响因素。要进行大气污染防治,首先要对大气污染物的来源和致因机理进行研究。拟从系统方法论的新角度出发,以京津翼地区其中的代表城市天津为研究案例,探索将经典实用的事故树方法(FTA)应用在燃煤与灰霾的致因机理以及风险因子管理的新问题上。通过识别和辨明导致燃煤废气大量排放的直接和潜在原因,构建了"灰霾天气-燃煤废气过量排放"的事故树,基于最小割集、结构重要度、概率重要度以及临界重要度分析,定性、定量地评价了关键风险因子/事件对灰霾天气的贡献和影响。分析结果表明,能源结构不合理,没有合适可替代的清洁能源导致煤的大量燃烧是影响最大的关键风险因子。本工作可为灰霾天气的致因机理分析,风险因子防控以及管理提供一套科学有效的新思路和方法。

Haze weather characterized by PM2.5has become a serious environmental pollution problem in majorChinese cities recently,which has bad effect on the air quality and human health.Coal burning may be one of thecritical factors of haze pollution because coal is the most important energy source in China.It is significant to figureout the pollutant sources and causation mechanism of urban haze to indicate directions and support theoretical basisfor the atmospheric pollution prevention and control.Based on a new perspective of systematic methodology,thefault tree analysis(FTA)method is employed and investigated for the causation mechanism analysis and riskmanagement of urban haze related to coal burning for Tianjin in this work.All of the important risk factors arediscussed and identified by using this deductive FTA method.After the fault tree“haze weather-excessemission of coal-fired exhausts”is established,the qualitative and quantitative assessments based on theminimal cut sets,the structure,probability and critical importance degree analysis of those risk factors in thefault tree system are also carried out for Tianjin city.The analysis results show that“unreasonable energy structure”and“without sustainable cleaner energy”are the most important risk factors for causing excess coalburning.This study may provide a new scientific and effective tool/strategy for the causation mechanism analysis and risk management of haze pollution in China.