Ground based in situ observations of filter_2pack at Virolahti II (FI0017R). These measurements are gathered as a part of the following projects HELCOM, EMEP and they are stored in the EBAS database (http://ebas.nilu.no/). Parameters measured are: sulphur_dioxide in air (mass_concentration_of_sulphur_dioxide_expressed_as_sulphur_in_air), sum_nitric_acid_and_nitrate in air+aerosol (mass_concentration_of_sum_nitric_acid_and_nitrate_expressed_as_nitrogen_in_aerosol)