Nothing in this Chapter shall be construed as preventing or restricting the practice, services, or activities of:
(1) Any person licensed in this state by any other law from engaging in the profession or occupation for which he is licensed.
(2) Any person employed as a respiratory therapist by the United States government if such person provides respiratory therapy solely under the direction or control of the United States governmental organization by which he is employed.
(3) Any student pursuing a course of study in an approved respiratory therapy education program, provided that such respiratory therapy practices, activities, and services are necessary to meet the requirements of the program. Any such student shall be referred to as a "student respiratory therapist" and shall use the letters "SRT" during clinical training to denote his status as a student or trainee.
(4) Any person not licensed as a respiratory therapist who may be employed in a pulmonary testing laboratory or physician's office, provided such practice is confined to that laboratory or office under the direction and immediate supervision of a licensed physician.