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

微小到肉眼看不见的粒子在大气中非常丰富。它们来自广泛的来源(例如道路交通)，并且它们的颗粒大小和化学成分各不相同。早些时候的流行病学研究清楚地表明，暴露在空气中的颗粒物对人类健康有影响，在高污染日和紧随其后的日子里，因呼吸系统和心血管疾病而死亡和住院的人数会更多。然而，到目前为止，流行病学主要集中在被称为PM2.5和PM10的大尺寸颗粒的质量上，还没有发现颗粒的特定属性，如它们的大小或化学成分是否决定了相对毒性。这样做会有很大的好处，因为减排战略可以把重点放在排放最有毒颗粒物的来源上。在这个项目中，建议收集不同大小的空气颗粒物的大样本，包括被认为单位质量具有较高毒性的超细颗粒(直径小于100纳米)。颗粒样本将在实验室接受详细的化学分析，并测试其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物的哪些性质对其氧化潜能影响最大，然后可以设计流行病学研究，调查这些颗粒物性质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.