Cognitive DeveLopment in the Urban Environment (The CLUE study)

随着人口增长和城市化进程的持续，空气质量和城市噪音已成为全球和欧洲疾病负担以及城市公共卫生的重要决定因素。伦敦最繁忙道路上的空气污染浓度继续超过英国空气质量战略目标（AQS）和欧盟限值，环境健康和肺部探索（EXHALE）表明，大约80%居住在伦敦内城各区的儿童每年接触到的二氧化氮超过欧盟限值（40微克/立方米），这反映了柴油车辆的高比例。在人口密集、交通繁忙的城市地区，城市噪音也是一个问题。据预测，在伦敦，19%的人口暴露在超过世卫组织指导标准的住宅噪音水平下，100%的人暴露在超过世卫组织指导标准的夜间噪音水平下。最近的研究表明，长期暴露在空气污染和噪音中可能会对儿童的认知、学习成绩和行为产生不利影响，但科学证据有限，对这些影响的潜在机制知之甚少。该提案旨在调查一个新兴的假设，即在城市环境中出生和长大的儿童由于长期暴露于空气污染和交通噪音中而表现出认知发育受损。CLUE研究将在大伦敦6000名中学生的SCAMP研究中进行，将利用详细的空气污染和噪音暴露监测（包括个人监测和家庭和学校的室内和室外测量）来改进现有的模型，以估计该年龄组的空气污染和噪音暴露。这些增强的模型将用于估计所有SCAMP儿童的空气污染和噪音暴露。这种应用于大型纵向数据集的增强建模方法将有助于克服先前试图调查空气污染、噪音、认知、行为和学术成就之间相互关系的研究的许多局限性。我们还将研究空气污染和噪音可能影响SCAMP队列儿童认知发展的潜在生物学机制。越来越多的证据表明，与交通有关的污染/噪音会影响神经发育和退化，这引发了重大的公共卫生和社会问题。迄今为止，大部分焦点都集中在柴油废气排放上，但由于研究设计、建模方法和暴露概况（即污染物浓度和趋势、混合成分和交通车队组成）在研究之间的差异，证据基础并不完全一致。在伦敦进行的一项大规模的纵向研究，研究了交通相关的空气污染和噪音暴露与儿童认知发展之间的联系，因此为评估这种联系提供了一个独特的机会。伦敦的二氧化氮水平很高，很大程度上是因为柴油车的高比例，因此是检验这一假设的理想地点。由于交通污染/噪音与认知发展受损之间的潜在联系在社会和经济层面都具有重要意义，本研究有可能为一系列部门的政策提供信息，以：(a)提高对这些环境压力因素对儿童大脑发育和教育表现的潜在影响的理解；(b)通过确定影响接触的主要决定因素，为交通缓解计划和城市规划提供信息，以确定减少儿童接触噪音和空气污染的方法；(c)侧重于来源信息建模估计暴露和潜在的不利机制途径，以确定城市空气污染组合的哪些组成部分最有可能导致不利的认知结果。

With increasing population growth and continuing urbanization, air quality and urban noise have emerged as important determinants of the global and European burden of disease, as well as public health within cities. Air pollution concentrations on London's busiest roads continue to exceed UK Air Quality Strategy Objective (AQS) and EU Limit Values, with the Exploration of Health and Lungs in the Environment (EXHALE) demonstrating that approximately 80% of children living in Inner City London boroughs have annual exposures to NO2 in excess of the EU limit value (40 ug/m3), reflecting the high proportion of diesel vehicles. Urban noise also constitutes a problem in densely populated, highly trafficked urban areas. In London, it is predicted that 19% of the population are exposed to residential noise levels, and 100% to night-time noise levels, that exceed WHO guidelines. Recent research suggests that chronic exposure to air pollution and noise may have detrimental effects on cognition, academic performance and behaviour in children, but there is limited scientific evidence and very little is known about possible underlying mechanisms for these effects.This proposal sets out to investigate the emerging hypothesis that children who were born in and grow up in urban environments display impaired cognitive development due to long-term exposures to air pollution and noise from traffic. The CLUE study, which will be nested within the SCAMP study of 6000 secondary school children in Greater London, will exploit detailed air pollution and noise exposure monitoring (including personal monitoring and indoor and outdoor measurements at homes and schools) to enhance existing models for estimating air pollution and noise exposure in this age group. These enhanced models will then be used to estimate air pollution and noise exposure in all SCAMP children. This enhanced modelling approach, applied to a large longitudinal data set will help overcome many of the limitations of previous research that have attempted to investigate the interrelationships between air pollution, noise, cognition, behaviour and academic attainment. We will also investigate the underlying biological mechanisms by which air pollution and noise may impact on cognitive development using a subset of the children from the SCAMP cohort.The emerging evidence that traffic-related pollution/noise impacts on neurological development and degeneration raises significant public health and societal issues. To date much of the focus has been on diesel exhaust emissions, but the evidence base is not wholly coherent due to differences in study design, modelling approaches and exposure profiles (i.e. pollutant concentrations and trends, mixture composition and the make-up of the traffic fleet) between studies. A large-scale longitudinal study within London, examining associations between traffic-related air pollution and noise exposures and cognitive development in children therefore provides a unique opportunity to evaluate this association. London has high levels of NO2, largely arising from the high proportion of diesel vehicles and therefore represents an ideal location to test this hypothesis. As a potential association between traffic-related pollution/noise and impaired cognitive development is of significance at both a societal and economic level, this research has the potential to inform policy across a range of sectors to:(a) improve understanding of potential impacts of these environmental stressors on children's developing brains and educational performance;(b) through identifying the major determinants of exposures to inform traffic mitigation schemes and urban planning to identify ways to reduce noise and air pollution exposure among children;(c) by focusing on source informative modelling estimates of exposure and potential adverse mechanistic pathways to identify which components of the urban air pollution mix are most likely to drive adverse cognitive outcomes.