When the electrochemical concentration cell (ECC) ozonesonde exhibits a background current at the time of balloon launch, the measured cell current must be corrected to obtain the actual ozone response. We have found a pressure dependent factor in the background current that originates in a convective mass transport parameter. For atmospheric pressures greater than 100 mb, the mass transport parameter is constant, but at pressures less than 100 mb it declines logarithmically with pressure. We suggest that the background current correction is directly correlated to the mass transport parameter pressure dependence. Compared to a constant background current, the presently used background current correction based on the oxygen partial pressure leads to an overestimate of the integrated ozone value in the troposphere for the ECC ozonesonde data.