Ground based in situ observations of high_vol_sampler at Houtem (BE0013R). These measurements are gathered as a part of the following projects CAMP and they are stored in the EBAS database (http://ebas.nilu.no/). Parameters measured are: benz_a_anthracene in pm10 (mass_concentration_of_benz_a_anthracene_in_pm10_in_air), benzo_a_pyrene in pm10 (mass_concentration_of_benzo_a_pyrene_in_pm10_in_air), benzo_ghi_perylene in pm10 (mass_concentration_of_benzo_ghi_perylene_in_pm10_in_air), chrysene in pm10 (mass_concentration_of_chrysene_in_pm10_in_air), fluoranthene in pm10 (mass_concentration_of_fluoranthene_in_pm10_in_air), inden_123cd_pyrene in pm10 (mass_concentration_of_inden_123cd_pyrene_in_pm10_in_air), pyrene in pm10 (mass_concentration_of_pyrene_in_pm10_in_air)