The optical properties of black carbon

气溶胶颗粒非常小，你可以在人的头发丝的宽度上排列一百个。它可以漂浮在空气中，几乎不被发现。这些颗粒对人类健康很重要：例如花粉会引起花粉热。石棉被用于20世纪60年代建造的建筑物，当受到干扰时会产生气溶胶，如果吸入，可能导致肺癌（在英国，每年约有3500人因石棉气溶胶而过早死亡）。气溶胶在气候变化中也发挥着重要作用。大多数人都知道，全球变暖是由于二氧化碳等气体释放到大气中，但气溶胶也发挥了重要作用。存在于大气中的气溶胶倾向于将阳光反射回太空，导致地球大气层冷却。然而，一些气溶胶，例如来自火灾和旧柴油汽车，是由碳制成的，实际上吸收了太阳光。这使大气变暖。气溶胶对气候也有间接的影响：例如，云中的每个水滴通常是在气溶胶颗粒周围形成的，因此大气中更多的气溶胶也会影响云的形成。尽管我们对气溶胶有很多了解，但它们对全球变暖的总体影响还不确定。目前还不清楚它们是冷却还是加热了地球。这对于吸收光的碳气溶胶来说尤其如此。该项目测量的光学特性决定了黑碳气溶胶对变暖的贡献，以及随着气溶胶的老化，这种贡献如何变化。许多国家（例如，中国）正在经历经济和工业增长的长期时期，这种增长可能在未来几十年继续下去。这种增长伴随着微量气体和微粒排放量的大幅增加，对区域空气质量和全球气候产生了严重影响。我们获得的信息将使政府能够管理气溶胶空气污染，从而改善空气质量和公众健康。

An aerosol particle is so small that you could line up one hundred in the width of a human hair. It can float in the air almost undetected. These particles are important for human health: for example pollen causes hay fever. Asbestos, which was used in buildings built in the 1960s can generate an aerosol when disturbed that, if inhaled, can lead to lung cancer (in Britain around 3500 people die prematurely each year because of asbestos aerosols). Aerosols also play an important role in climate change. Most people are aware that global warming is due to gases such as carbon dioxide released into the atmosphere, but aerosols also play an important role. Aerosols present in the atmosphere tend to reflect sunlight back into space, causing cooling of the Earth's atmosphere. Yet some aerosols, for example from fires and old diesel cars, are made from carbon and actually absorb the Sun's light. This warms the atmosphere. Aerosols also have an indirect effect on the climate: for example each water droplet in a cloud is normally formed around an aerosol particle, so more aerosols in the atmosphere will also affect how clouds form. Despite all that is known about aerosols their overall effect on global warming is uncertain. It is unclear if they cool or heat the Earth. This is particularly true for the light absorbing carbon aerosols. This project measures the optical properties that determines how much warming black carbon aerosols contribute, and how this changes as the aerosol ages. Many countries (e.g., China) are experiencing extended periods of economic and industrial growth that is likely to continue in future decades. This growth is accompanied by large increases in emissions of trace gases and particles, with serious implications for regional air quality and global climate. The information we gain will allow the government to regulate aerosol air pollution, hence improving air quality and public health.