ABSTRACT
This chapter addresses the issue of the source apportionment of particles in the atmosphere of the UK. It summarizes some of the main findings of the group as well as referring to relevant results of recent research work. Atmospheric particles exist in a very wide range of sizes and have a variety of chemical compositions. The size distribution is typically trimodal., this distribution reflecting the sources and behaviour of atmospheric particles. The modes in the size distribution are as follows: Transient nuclei generally smaller than 100 nm in diameter, Accumulation mode, and Coarse particles: particles of greater than about 2.5 µm. At the time of publication of the Third Report of the Quality of Urban Air Review Group , knowledge of the source attribution of particles was rather basic, and from measurements within the atmosphere, it was possible to identify three main groupings of particles: primary combustion particles, secondary particulate matter, and coarse particles.
