Analysing urban aerosols using a digital camera

Abstract

This dissertation tests the idea that 'off the shelf' digital cameras can be used to supplement or replace more cumbersome methods of detecting and classifying urban aerosols. Currently, most aerosol observations are made using expensive and specialised equipment that can often only analyse a small portion of the sky at a time. In contrast, the recent proliferation of high-resolution wide-field colour digital cameras with advanced noise reduction makes feasible the use of colorimetric image calibration to provide a cost-effective alternative for monitoring air pollution for research, education and outreach purposes. Nitrogen dioxide and carbonaceous (soot) aerosols from human activities are the two main types of discolouring aerosols causing the haze and choking dust commonly observed in many large cities, particularly Asian megacities such as Tokyo. These aerosols deserve more extensive study due to their potential for widespread negative effects on climate, ecosystems, human health, and transportation. This dissertation thus involved the use of a digital camera for repeated imaging of Tokyo's polluted skies under different meteorological conditions, with images subjected to detailed colorimetric calibration and analysis. This work included the effects of a volcanic eruption that fortuitously occurred near Tokyo during this study. The results obtained in this thesis indicates that a modern mass-market digital camera produces wide-field colorimetric aerosol data of comparable accuracy to that obtained from expensive specialised equipment and models. Such an outcome can be used to promote more widespread monitoring of aerosols and greater awareness and understanding of the local effects of air pollution.