a process for treatment of a secondary gas including ozone , comprising the steps of : a ) adding an adjacent gas including co 2 to the secondary gas to form a mixture of secondary gas and adjacent gas ; b ) passing the mixture of secondary gas and of adjacent gas obtained at the end of stage a ) into at least one stock of adsorbent , where the ozone is completely or partly adsorbed ; c ) sweeping the stock of adsorbent with the aid of a desorbing gas including co 2 , and discharging from an outlet of the stock an output gas including ozone , wherein the ozone has a concentration which is higher in the output gas than the ozone concentration of the secondary gas .