Quantitative Attribution of Secondary Organic Aerosol in Beijing to its Precursors

吸入污染空气中的颗粒物会导致许多健康状况恶化，最终导致过早死亡。北京的大气以空气中颗粒物浓度非常高而闻名，迫切需要采取进一步的控制措施。其中很大一部分颗粒物(称为“雾霾”)不是直接排放到大气中，而是在大气中通过气体和蒸汽的化学反应形成的。该项目致力于找出道路交通、燃料燃烧、垃圾焚烧和许多其他来源排放到大气中的哪些气体和蒸气是北京大气中颗粒物形成的原因，以及它们对颗粒物浓度的贡献。科学的方法是在反应室里装满单一化合物的蒸气，让它们经历导致粒子形成的化学反应。然后对形成的颗粒进行非常详细的化学分析，并确定组成分子，这些分子是最初放入室内的化合物的特征。然后，通过测量大气中的同一化合物，就有可能估计有多少颗粒是由特定气体的反应产生的。然后，可以制定控制政策，以减少那些对颗粒物形成负有最大责任的气体的排放。

Breathing particles in polluted air leads to the worsening of many health conditions and ultimately to premature death. The atmosphere of Beijing is well known for its very high concentrations of airborne particles and there is an urgent need for further control measures. A large proportion of those particles (referred to as "haze") are not emitted directly into the atmosphere but form within the atmosphere from chemical reactions of gases and vapours. This project is concerned with finding out which gases and vapours emitted into the atmosphere from road traffic, fuel burning, refuse incineration and many other sources are responsible for the formation of particles within the atmosphere of Beijing and the amount which they contribute to the concentration of particles. The scientific approach is to fill a reaction chamber with the vapours of a single chemical compound and let them undergo chemical reactions which lead to particle formation. The particles formed are then subject to very detailed chemical analysis and constituent molecules are identified which are characteristic of the compounds originally put into the chamber. Then, by making measurements of the same compound in the atmosphere, it is possible to estimate how much of the particles arise from the reaction of a particular gas. Control policies can then be formulated to reduce the emissions of those gases most responsible for particle formation.