There was some firm in the early '80s was interested in fitting
some sort of electronic plate to our DC8 air intakes with a view
to neutralizing the ozone coming in to the aircraft.
Unfortunately we went bust before anything was done about it.
Often wonder if anything was eventually fitted to ANY aircraft.
People were aware of the problem then.
The air recirculation system used on most modern aircraft just
helps to keep the fuel burn figures acceptably LOW.