Off-gases from nuclear plants are basically treated in the following sequence: Wet gases: washing in columns and/or Venturi washers, wet filtering, drying, absolute filtering through aerosol filter of special class S, off-gas blower, Dry gases: prefiltering, absolute filtering through aerosol filter of special class S, off-gas blower, Hot gases from the combustion of radioactive waste: post-burning and dust retention in sinter ceramic candles (temperature up to 1000ºC), post-filtering with sintered ceramic or sintered metal filters at temperatures up to 700ºC, further purification as for dry gases. Iodine and ruthenium require special measures