Can planes damage the ozone layer?
Yes, high flying jets can damage the ozone layer, but the consensus of opinion is that at present this damage is trivial and nothing to worry about. If, on the other hand, Concorde-type supersonic transports were to become commonplace, it might be another matter. It was found that Concorde's engines produced much more sulphuric acid particles than the exhausts of subsonic aircraft, and it was this sulphuric acid that damaged the ozone layer. Whether or not enough supersonic military aircraft fly at the relevant altitude and cause significant damage is something nobody seems to know, but probably not. The jets need to fly at altitudes between about 30,000 feet and 45,000 feet to cause ozone damage.