Any DOT employee shall permanently disqualify himself or herself from participation in every matter before the Department in which he or she previously personally and substantially participated for an interested person or entity, including other agencies of the United States Government, before joining the DOT or the Civil Aeronautics Board. Such disqualification shall be applicable also if a person is closely related to is a DOT employee as partner, associate, employer, or the like, personally and substantially participated in a matter before DOT prior to the employee's employment by the Department or the Civil Aeronautics Board and the circumstances were such that the DOT employee's subsequent participation in the matter as a DOT employee could fairly be said to create the appearance that his or her participation would be affected by his or her prior relationship. Notwithstanding the foregoing, the disqualification of any DOT employee, including any member of a DOT employee's personal staff or a special Government employee, whose prior personal and substantial participation in a DOT or Civil Aeronautics Board proceeding or whose relationship to one who so participated occurred on behalf of another agency of the United States Government shall only be applicable with respect to issues on which the prior governmental employer took a position in the proceeding unless participation could fairly be said to create the appearance that his or her participation would be affected by his or her prior relationship.