Ground based in situ observations of high_vol_sampler at Montseny (ES1778R). These measurements are gathered as a part of the following projects EMEP, GAW-WDCA, EUSAAR and they are stored in the EBAS database (http://ebas.nilu.no/). Parameters measured are: ammonia in pm25 (mass_concentration_of_ammonia_in_pm2p5_in_air), nitrate in pm25 (mass_concentration_of_nitrate_in_pm2p5_in_air), sulphate_total in pm25 (mass_concentration_of_sulphate_total_in_pm2p5_in_air), titanium in pm25 (mass_concentration_of_titanium_in_pm2p5_in_air)