Ozone is not very good for the cabin inhabitants health.
Most commercial flights cruise near the edge of the troposphere where naturally occuring ozone rarely exists in quantity. Ozone can enter and recirculate in even modern cabin air filtration systems including the HEPA types used on the 777. In an event such as you describe, a lower altitude is the only remedy.
A Concorde flight would not have requested a descent as it is (as far as I know) the only airliner to include an ozone-removing component in the air system.