Clear association exists between exposure to even small concentrations of ambient atmospheric particles with an aerodynamic diameter < 10 Ilm (PMIO) and adverse health outcomes. However, determination of the strength of associations between exposure and illness is limited by low spatial-resolution of particulate concentration measurements. Conventional fixed monitoring stations provide high temporal-resolution data, but cannot capture fine-scale spatial variations. Biomagnetic monitoring of PMIO deposited on tree leaves may provide a means of obtaining exposure data at high spatial resolution. To calculate ambient PMIO concentrations from leaf magnetic values, the relationship between the magnetic signal and total PMIO mass and leaf exposure time must be quantified. This thesis uses magnetic remanence measurements of roadside tree leaves and co-located pumped air filters to examine levels of vehicle - and industry - derived PMIO at three locations within the UK. At the roadside, leaf saturation remanence (SIRM) values exhibit strong correlation with both the SIRM and particulate mass of co-located, pumped-air samples, indicating that these leaf magnetic values are an effective proxy for ambient PMIO concentrations. Two broadleaf deciduous species reach dynamic equilibrium between leaf magnetic remanence and ambient PMIO over a relatively short timescale (- 6 days), indicating that the leafcalculated PMIO reflects ambient PMIO concentrations. Multiple co-located species can be robustly inter-calibrated, enabling maximisation of the spatial resolution of this technique. A different but equally strong correlation also exists between leaf SIRM and ambient PMIO around a major industrial point source. To reduce ambient PMIO concentrations, it is often necessary to identify particulate sources, particularly in complex areas where multiple sources are present andlor in complex topography. To address this issue, I combine magnetic measurements of tree leaves, putative To address this issue, I combine magnetic measurements of tree leaves, putative 11 I J 'j 11 :1 :Ij, :1 :1 I 'I , , , a -------- ,-~-- --------- sources and road dusts to examine if magnetic differentiation can be made between the potential sources and sinks. Particulate assemblages emitted from vehicle fleets (e.g. diesel/petrol) and a range of industrial sources differ in their measured magnetic characteristics, indicating the value of magnetic techniques for particulate source attribution.