Cognitive DeveLopment in the Urban Environment (The CLUE study)

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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.