Field measurement of particle size and number concentration with the Diffusion Size Classifier (DiSC)

The Diffusion Size Classifier (DiSC) is a new instrument to measure number concentration and average diameter of nanometer sized particles in the size range 10 - 200nm. It is small, easily portable and battery operated and therefore well suited for field measurements. The measurement range is suitable for ambient air concentrations (1000 - 500000 particles/cm 3 ); together with a diluter it can be used for emission measurements. The number concentrations measured with DiSC agree well with those measured with a condensation particle counter. The response time is short enough to measure transient engine operation. The DiSC is therefore a useful instrument for number concentration measurements in non-laboratory settings.