The physical nature of airborne particulate matter (PM10) in Plymouth, UK

Plymouth aerosol has been directly collected on to transmission electron microscopy grids at both roadside and background sites at the University of Plymouth. Photographs of 50 randomly selected particles were taken. The particle images were collected and measured using a Quantimet 570 image analyser. Two box-counting procedures approximating to fractal dimensions were applied to the collected particle images. Comparison of the fractal dimensions of roadside and background particles shows there is a structural change in particles from road to background in the 220-320 nm size range. Within this range, roadside particles;are both more dense and have a more convoluted surface than the same size aerosol in the background. It is reasonable to assume that roadside particles will therefore have a deeper lung penetration and greater surface loading of material than their counterparts in the background aerosol.