Ground based in situ observations of nephelometer at DEM_Athens (GR0100B). These measurements are gathered as a part of the following projects ACTRIS, GAW-WDCA and they are stored in the EBAS database (http://ebas.nilu.no/). Parameters measured are: aerosol_light_backscattering_coefficient in pm10, aerosol_light_scattering_coefficient in pm10