Ground based in situ observations of filter_1pack at Leba (PL0004R). 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: ammonia in air (mass_concentration_of_ammonia_expressed_as_nitrogen_in_air), nitric_acid in air (mass_concentration_of_nitric_acid_expressed_as_nitrogen_in_air)