This European Standard describes the paramagnetic method, including the sampling and the gas conditioning system, to determine the oxygen concentrations in flue gases emitted to the atmosphere from ducts and stacks. This European Standard is the Standard Reference Method (SRM) for periodic monitoring and for the calibration or control of Automatic Measuring Systems (AMS) permanently installed on a stack, for regulatory purposes or other purposes. To be used as the SRM, the user shall demonstrate that the performance characteristics of the method are better than the performance criteria defined in this European Standard and that the overall uncertainty of the method is less than ± 6,0 % of the measured concentration. NOTE When paramagnetism is the measurement principle used for AMS, reference should be made to EN 14181 and other relevant standards provided by CEN/TC 264. An alternative method to this SRM may be used provided that the user can demonstrate equivalence according to the Technical Specification CEN/TS 14793, to the satisfaction of his national accreditation body or law. This Standard Reference Method has been evaluated during field tests on waste incineration, co-incineration and large combustion installations. It has been validated for sampling periods of 30 min in the range: 5 % to 26 %. Oxygen concentration values, expressed in % volume, are used in order to allow emission measurements of pollutants to be standardised to the reference O2 concentration and dry gas conditions required by the following Council Directives: Council Directive 2001/80/EC on the limitation of emissions of certain pollutants into the air from large combustion plants; Council Directive 2000/76/EC on waste incineration plants.