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，在国家和国际层面都受到监管。PM产生于直接吹入空气中的固体和液体颗粒以及凝结成液滴的气体。PM与死亡率增加直接相关，特别是非常小的颗粒（<100 nm），可以使肺部深处的组织发炎。在英国，PM的最大来源之一是道路交通，其中包括发动机尾气排放，轮胎和刹车磨损以及路面扬起的灰尘。在过去的二十年里，由于法规推动车辆使用更清洁的内燃机，交通排放的PM量大幅减少。然而，随着道路上车辆数量和重量的增加，非废气源（如轮胎和刹车）排放的颗粒也越来越多。与化石燃料燃烧的副产品不同，这些颗粒没有很好地表征。例如，目前尚不清楚什么驾驶条件会增加非废气颗粒的产生，这些颗粒是否小到足以影响人类健康，以及这些颗粒如何与大气中的气体相互作用。人类活动产生的颗粒物也是气候变化的一个重要因素。化石燃料燃烧产生的煤烟颗粒，包括柴油和汽油汽车尾气中的煤烟颗粒，会吸收阳光，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，以绘制出全球的PM水平。为了从卫星测量中准确地确定PM浓度，了解不同类型的粒子如何与光相互作用是很重要的。这些信息对于利用计算机模拟大气来预测未来的气候变化也是至关重要的。由于道路交通产生的颗粒类型随着时间的推移而变化，这些颗粒与入射阳光的相互作用将受到影响。在这个研究项目中，我将建造三种仪器，以更好地了解英国典型城市中心道路交通产生的颗粒特征。第一种仪器将测量颗粒的大小，这是与公共卫生官员直接相关的信息，他们可以将未来减少污染的努力集中在检测到微小颗粒的地区。另外两个将测量空气中粒子吸收和反射的光。这些数据对于检查用于预测未来气候变化的计算的准确性和卫星报告的信息是有用的。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，因为气体和颗粒密切相关。

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.