Results of measurements in an underground laboratory, 70m of water equivalent below surface, are given. Background values of proportional gas counters with volumes between 16cc and 1.5L are lower by a factor of 2—4.5 compared to the values in the previously used laboratory (7m w.e.). High counting gas pressures, up to 5 at CH₄ and up to 36 at P-10, enable the use of relatively small counters with correspondingly small background contributions from the walls. A separation of the residual background into different components is attempted, distinguishing a pressure dependent volume effect and surface correlated contributions. It can be shown that the selection of radioactively pure counter construction material is very important for a good low level counting system.