Carbon bodies are heated in an oven under low pressure and while being swept with an inert gas, gaseous effluent containing elemental or compound sodium in sublimed form being continuously extracted from the oven via an effluent exhaust pipe. At least one sodium-neutralizing agent is injected into the effluent exhaust pipe immediately downstream from the outlet for exhausting gaseous effluent from the oven. The sodium-neutralizing agent is selected from carbon dioxide and steam, and it can be injected continuously into the flow of gaseous effluent.