Ground based in situ observations of aps at Observatoire Perenne de l'Environnement (FR0022R). These measurements are gathered as a part of the following projects ACTRIS, GAW-WDCA and they are stored in the EBAS database (http://ebas.nilu.no/). Parameters measured are: particle_number_size_distribution in aerosol (number_concentration_of_positive_ions_in_dry_aerosol_particles_in_air), particle_number_size_distribution in aerosol (number_concentration_of_positive_ions_in_dry_aerosol_particles_in_air), particle_number_size_distribution in aerosol (number_concentration_of_positive_ions_in_dry_aerosol_particles_in_air)