Ground based in situ observations of particle_number_size_distribution at Schauinsland (DE0003R) using v-smps. These measurements are gathered as a part of the following projects GUAN, ACTRIS, EMEP, GAW-WDCA and they are stored in the EBAS database (http://ebas.nilu.no/). Parameters measured are: particle_number_size_distribution in pm10_non_volatile (mass_concentration_of_particle_number_size_distribution_in_refractory_pm10_in_air)