Below-cloud scavenging of atmospheric aerosol by precipitation is a deposition process particularly efficient on short time scales. However, the efficiency of this phenomenon is relatively unknown for in situ conditions, in particular regarding nanometric particles. Rainfall data and particle sizes were measured on a minute-basis with an optical disdrometer PARSIVEL associated with two different granulometers. Measurements were performed during several months and at different sites according to their climatic conditions and dust levels. Washout coefficients for aerosols with diameter between 5 nm and 32 μm are calculated at the rainfall event scale (values registered before the beginning and after the end of the rain), thus called macroscopic approach. Washout potentials depend on the rain type. Mean dust levels have no impact on these potentials. Another method can be used to eliminate bias induced by this macroscopic approach.