Deteriorating air quality is now recognised as the biggest environmental risk to human health, with evidence of both short and long-term effects on respiratory and cardiovascular morbidity and mortality. Recent evidence has demonstrated that urban air pollution, especially that derived from traffic sources is also associated with poor cognitive development in children and increased incidence of dementia in the aged population. While these associations appear robust, the causal mechanisms by which air pollutants impact on the brain are not well understood, though it has been proposed that airborne particles may access the brain via uptake by olfactory neurons. In this studentship, we aim to employ Grey squirrel populations across the urban-rural gradient in the UK as a biological sentinel species to investigate the neurotoxicity of air pollution. We will utilise tissues harvested from animals culled as part of ongoing pest control measures to examine the following issues: (a) whether particles accumulate in the brain of squirrels in urban environments and are associated with modelled estimates of pollution exposures; (b) the spatial distribution of neurotoxic metals in the brain and their relation to markers of neuroinflammation and overt histological features associated with neurodegeneration; and (c) epigenetic modification within the brain as a marker of long term pollutant exposure. In addition, to providing information on the causal pathways linking air pollution to negative impacts on the brain in the human population, this data will also indicate how traffic pollution impacts on urban wildlife itself. This project is a collaboration between ZSL and KCL.