Determinants of Oxidative Potential, A Health-Based Metric to Assess Particulate Matter Toxicity

大气中有大量的小到肉眼看不见的微粒。它们来自广泛的来源（例如道路交通），其颗粒大小和化学成分各不相同。早期的流行病学研究清楚地表明，暴露于空气中的颗粒物会对人类健康产生影响，在高污染日和随后的日子里，会有更多的人死亡，并因呼吸道和心血管疾病住院。然而，到目前为止，流行病学主要集中在被称为PM2.5和PM10的宽尺寸范围内的颗粒物的质量上，并且尚未发现颗粒物的特定性质（例如其尺寸或化学成分）是否决定相对毒性。这样做会有很大的好处，因为减排战略可以集中在排放最有毒颗粒的来源上。在该项目中，建议收集不同大小部分的大量空气传播颗粒物样品，包括超细部分（直径小于100纳米），据信这种颗粒物每单位质量的毒性较高。这些颗粒样品将在实验室进行详细的化学分析，并测试它们发挥氧化潜力的能力，换句话说，消耗人体的抗氧化防御能力。总体目标是了解颗粒的哪些特性对其氧化潜力影响最大，然后可以为流行病学研究的设计提供信息，以调查这些颗粒特性与对人类健康的影响之间的联系。

Particles which are so small as to be invisible to the naked eye are very abundant in the atmosphere. They come from a wide range of sources (e.g. road traffic) and are diverse in terms of their particle sizes and chemical composition. Earlier epidemiological studies have shown clearly that exposure to airborne particles has an impact on human health with more deaths and hospital admissions for respiratory and cardiovascular diseases on high pollution days and those immediately following. However, to date the epidemiology has focussed very largely on the mass of particles in wide size ranges known as PM2.5 and PM10 and has not discovered whether particular properties of the particle such as their size or chemical composition determine the relative toxicity. There would be great benefit in doing so as abatement strategies could then focus on the sources emitting the most toxic particles. In this project it is proposed to collect large samples of airborne particles in different size fractions including the ultrafine fraction (of less than 100 nanometres diameter) which is believed to have a higher toxicity per unit mass. The samples of particles will be subjected to detailed chemical analysis in the laboratory as well as being tested for their ability to exert oxidative potential, in other words, to consume the body's anti-oxidant defences. The overall aim is to understand which properties of the particles have the greatest influence on their oxidative potential which could then inform the design of epidemiological studies to investigate the links between those particle properties and effects on human health.