Linking Particulate Matter Oxidative Potential to Atmospheric Conditions and Particle Composition

空气污染暴露是一个重大的全球健康问题；2019年，99%的世界人口生活在空气质量标准超过世界卫生组织(WHO)最近制定的指导标准限制的地方，每年有超过700万人过早死亡。世界卫生组织最近将暴露于直径小于2.5微米的空气中颗粒物(PM2.5)的空气质量指南限值从每年平均暴露10微克m-3降低到5微克m-3，因为PM是空气污染中毒性最强的成分，是全球主要的健康负担。尽管有令人信服的证据明确地将暴露于颗粒物(PM)与有害的健康影响联系在一起，但PM的与健康相关的化学成分，以及它们在暴露时导致毒性的机制，仍然高度不确定。最近的研究广泛表明，PM氧化潜能(OP)是确定PM暴露对健康影响的关键，OP是一种描述PM内在毒性的生物相关化学指标。然而，由于缺乏合适的测量方法，阻碍了对OP的准确定量，因为许多对OP有贡献的化学成分都是短暂的，并且在低环境浓度下，这给分析化学带来了巨大的挑战。目前的政策旨在减少PM的所有来源，以减少对健康的影响；这不是一种成本效益高的方法，也是一种降低PM暴露的健康负担的低效方法。因此，OP有可能量化造成观察到的健康影响的驱动因素和具体来源，这对各国政府有效应对世卫组织最近的政策变化至关重要。然而，可靠和准确的量化对于确定与OP暴露有关的来源、大气驱动因素和健康后果至关重要。我的项目代表了我在博士和博士后生涯中开发的一种新型仪器的第一次应用。在线氧化电位抗坏血酸仪器(OOPAAI)可以以10分钟的时间分辨率对PM OP进行原位定量，通过提供更稳健和准确的OP测量，消除离线分析导致的测量伪影，并提供高度时间分辨率的数据，从而捕获与大气相关的时间尺度上的OP变化，从而大大改进PM OP的量化。该方法将被部署在实验室研究中，探测PM OP和环境现场活动的基本化学驱动因素，以及正在建立的大气污染测量，绘制英国几个不同环境中OP的时间和空间变异性。该项目将大大提高我们对影响有机磷农药的物理和化学大气成分的了解。此外，它将有助于澄清在环境PM浓度的贡献者因地方、国家和国际减排政策而发生变化时，PM OP最普遍的不同背景。该项目的成果将提供重要的证据，将来源与PM的内在毒性联系起来，并建立一种新的方法，用于可重复、可靠和长期的测量，这对于在未来的流行病学研究中将PM OP与健康结果相关联是至关重要的。

Air pollution exposure is a major global health issue; 99% of the world's population in 2019 lived in places where air quality standards exceed recent guideline limits set by the world health organisation (WHO), and is attributed to over 7 million premature deaths per year. The WHO recently reduced air quality guideline limits for exposure to airborne particulate matter less than 2.5 um in diameter (PM2.5) from 10 ug m-3 to 5 ug m-3 annual mean exposure, as PM is the most toxic component of air pollution and a major global health burden. Despite compelling evidence specifically linking exposure to particulate matter (PM) with adverse health effects, the health-relevant chemical components of PM, and the mechanisms by which they induce toxicity upon exposure, remain highly uncertain. Recent studies have widely suggested that PM oxidative potential (OP), a biologically relevant chemical metric describing intrinsic PM toxicity, is key to determining the health effects of PM exposure. However, accurate quantification of OP has been hindered by lack of suitable measurement methods, as many chemical components contributing to OP are short-lived and in low ambient concentrations, posing a significant analytical-chemical challenge. Current policy seeks to abate all sources of PM to reduce health impacts; this is not a cost-effective and is an inefficient approach to reducing the health burden of PM exposure. Thus, OP has the potential to quantify the drivers and specific sources that are responsible for observed health effects, which is crucial for governments to efficiently respond to recent WHO policy changes. However, robust and accurate quantification is essential to determine the sources, atmospheric drivers and health-outcomes related to OP exposure. My project represents the first application of a novel instrument that I developed during my PhD and post-doctoral career. The Online Oxidative Potential Ascorbic Acid Instrument (OOPAAI) can quantify PM OP in situ with a time resolution of 10 minutes, providing vastly improved quantification of PM OP by providing more robust and accurate OP measurement, eliminating measurement artefacts as a result of offline analysis, and providing highly time resolved data thus capturing OP changes on atmospherically relevant timescales. This method will be deployed in laboratory studies, probing fundamental chemical drivers of PM OP and ambient field campaigns alongside ongoing established atmospheric pollution measurements, mapping the temporal and spatial variability of OP across several different environments in the UK. This project will substantially improve our understanding of the physical and chemical atmospheric components influencing OP. Furthermore, it will help clarify the different contexts within which PM OP is most prevalent at a time when the contributors to ambient PM concentrations are changing due to local, national and international emission abatement policies. The outputs of this project will provide vital evidence linking sources to intrinsic PM toxicity, and establish a novel method for reproducible, robust and long- term measurements which are essential in order to correlate PM OP with health outcomes in future epidemiological studies.