The TRD 413 (technical standards for the steam boiler operation) dictate measures for the explosion protection in pulverized coal-fired boiler plants. During operation of these boiler plants with an inert atmosphere, the oxygen concentration in parts of the plant with pulverized coal/inert gas mixture has to be kept below the explosion limit. These are, depending on the type of coal and part of the plant, different. Oxygen measurements carried out in the Power Station Schwandorf of the Bayernwerk AG in the area of coal mills and dust pipes of Unit C and D show practical ways for keeping to the standards of the TRD 413. By returning the flue gas to the mill area with superimposed O-2-measuring, the inertness of fire- and explosion-endangered parts of the plant is reached.