Quantifying the health and climate impacts of vehicle particulate emissions

颗粒物（PM）是一种重要的大气污染物，在国家和国际层面受到管制。PM来自直接吹入空气中的固体和液体颗粒以及冷凝成液滴的气体。PM与死亡率增加直接相关，特别是非常小的（<100 nm）颗粒，可以使肺部深处的组织发炎。英国PM的最大来源之一是道路交通，其中包括发动机废气的排放，以及轮胎和制动器磨损和路面上的灰尘。在过去的二十年中，由于法规推动车辆中更清洁的内燃机，交通中排放的PM量大幅减少。然而，随着道路上车辆数量和重量的增加，来自非排气源（例如轮胎和制动器）的颗粒物排放量增加。与化石燃料燃烧副产物不同，这些颗粒没有很好的表征。例如，目前尚不清楚什么驾驶条件会增加非废气颗粒物的产生，这些颗粒物是否小到足以影响人类健康，以及这些颗粒物如何与大气中的气体相互作用。人类活动产生的PM也是气候变化的重要贡献者。化石燃料燃烧产生的烟尘颗粒，包括柴油和汽油车辆尾气中的烟尘颗粒，吸收阳光，加剧地球的净变暖。来自其他来源的颗粒，如冷凝气体，可以通过反射阳光对气候产生冷却作用。反射的阳光由卫星测量，以绘制出地球仪的PM水平。为了从卫星测量中准确地确定PM浓度，重要的是要了解不同类型的颗粒如何与光相互作用。这些信息对于利用计算机模拟大气预测未来气候变化也至关重要。由于道路交通产生的颗粒物类型随时间而变化，这些颗粒物与入射阳光的相互作用将受到影响。在这个研究项目中，我将建立三个仪器，以更好地了解在一个典型的英国城市中心的道路交通产生的颗粒的特性。第一台仪器将测量颗粒物的大小--这些信息与公共卫生官员直接相关，他们可以将未来的减少污染努力集中在检测到非常小的颗粒物的地区。另外两个将测量空气中颗粒吸收和反射的光。这些数据有助于检查用于预测未来气候变化的计算和卫星报告的信息的准确性。此外，我们可以将这些信息与现有的气体测量相结合，以更好地了解城市大气的化学性质，因为气体和颗粒物是密切相关的。

Particulate matter (PM) is a key atmospheric pollutant regulated at the national and international levels. PM arises from solid and liquid particles directly blown into the air and from gases that condense into droplets. PM has been directly linked to increased mortality, especially the very small (<100 nm) particles which can inflame tissue deep in the lungs. One of the largest sources of PM in the UK is road traffic, which includes emissions from engine exhaust, as well as tyre and brake abrasion and lofted dust from the road surface. Over the past two decades, the amount of PM emitted from traffic has decreased substantially due to regulations pushing for cleaner internal combustion engines in vehicles. However, as the number and weight of vehicles on the road increases, more particles from non-exhaust sources (e.g. tyres and brakes) are emitted. Unlike fossil fuel combustion byproducts, these particles are not well characterised. It is unknown, for example, what driving conditions enhance the production of non-exhaust particles, whether the particles are small enough to affect human health, and how these particles interact with gases in the atmosphere. PM produced by human activity is also an important contributor to changes in climate. Soot particles produced by fossil fuel combustion, including those found in the exhaust of diesel and petrol vehicles, absorb sunlight and enhance the net warming of the planet. Particles from other sources, such as condensed gases, can have a cooling effect on the climate by reflecting sunlight. Reflected sunlight is measured by satellites to map out the PM levels across the globe. In order to accurately determine PM concentration from satellite measurements it is important to understand how different types of particles interact with light. This information is also vital for predicting future changes in climate using computer simulations of the atmosphere. As the types of particles produced by road traffic changes over time, the interactions of these particles with incoming sunlight will be affected. In this research project, I will build three instruments to better understand characteristics of particles produced by road traffic in a typical UK city centre. The first instrument will measure the sizes of the particles - information directly relevant to public health officials who can focus future pollution reduction efforts on areas where very small particles are detected. The other two will measure the light absorbed and reflected by the particles in air. These data are useful for checking the accuracy of calculations used to predict future changes in climate and information reported by satellites. Additionally, we can combine this information with existing measurements of gases to better understand the chemistry of the urban atmosphere since gases and particles are closely linked.