A simple method exists to estimate the limiting oxygen concentration (LOC) based upon the lower explosion limit (LEL) by assuming (1) that the LOC lies at the apex of the explosion area, (2) that the LEL is unaffected by nitrogen addition and (3) that the apex of the explosion area lies on the stoichiometric line. This estimation method is assessed for mixtures relevant to the production of 1,2-dichloroethane. To this end, the explosion areas of ethylene/hydrogen/nitrogen/air, ethylene/nitrogen/air and ethylene/1,2-dichloroethane/hydrogen chloride/nitrogen/air mixtures are determined at typical process conditions. The experiments are performed in a closed spherical 81 vessel. The mixtures are ignited by fusing a coiled tungsten wire, placed at the centre of the vessel. A 5% pressure rise criterion is used to determine the explosion limits. The experimental procedure is based upon EN 14756. It is found that a safe estimate of the LOC of ethylene/hydrogen/nitrogen/air mixtures can be found based upon the LEL of these mixtures. (c) 2007 Elsevier Ltd. All rights reserved.