A Differential Mobility Particle Sizer (DMPS) operated by the University of Manchesetr which measures aerosol size distribution. The DMPS classifies particles according to electrical mobility in a differential mobility analyser and counts particles of given mobility using a condensation particle counter. The Manchester DMPS uses two such DMA’s and CPC of different specifications to measure aerosol size distributions from 3.5 – 800nm, with a complete scan taking ten minutes.