This project was the first to report ultrafine particle (UFP) number concentration and size distributions in the submicron (smaller than 1 micrometre) size range in urban Bangkok, Thailand.

It is well known that particulate matter (PM) poses a significant health risk, especially to urban dwellers, with often the poorest in society most affected. Ultrafine particles (size smaller than 100 nanometres), as a component of PM, are increasingly implicated in disease and mortality. However, much of the research available in the literature is based on data from the developed world, especially for ultrafine particles, and without robust data it is not possible to determine trends in this important pollutant for Thailand and Bangkok in particular, and strategies for health protection therefore lack this vital information. In addition, aerosol particles provide the single largest source of uncertainty in most global climate models, and production of primary particles and gas precursors e.g. Volatile Organic Compounds (VOCs) from the transport and industrial sectors contribute significantly to this. Therefore, in order for the impact of these activities on climate to be assessed and reduced, determination of sources and levels of emission of both gases and particles much be undertaken. NE/P014674/1