Ground based in situ observations of filter_1pack at Ispra (IT0004R). These measurements are gathered as a part of the following projects EMEP and they are stored in the EBAS database (http://ebas.nilu.no/). Parameters measured are: acidity in aerosol, ammonium in aerosol (mass_concentration_of_ammonium_expressed_as_nitrogen_in_dry_aerosol_particles_in _air), nitrate in aerosol (mass_concentration_of_nitrate_expressed_as_nitrogen_in_dry_aerosol_particles_in _air), pm10_mass in pm10 (mass_concentration_of_pm10_ambient_aerosol_particles_in_air), pm25_mass in pm25 (mass_concentration_of_pm2p5_ambient_aerosol_particles_in_air), sulphate_total in aerosol (mass_concentration_of_total_sulphateexpressed_as_sulphur_in_dry_aerosol_particles_in_air)