1. Although impaired pulmonary function is seldom the cause of sudden death, it may seriously affect operators of vehicles in the following ways:
   1. Sudden severe coughing while driving may result in an accident.
   2. Cough syncope may occur while driving.
   3. Impaired cerebral oxygenation or excessively high blood levels of carbon dioxide caused by impaired pulmonary function may result in mental confusion and/or impaired judgment.
2. For these and similar reasons, it is important to obtain an accurate picture of the pulmonary status of all applicants for driver licenses who have a history of problems or are observed to have respiratory difficulties at the time of examination.
3. In assessing the severity of pulmonary impairment, effort is made to limit the tests to those found in most medical offices, although occasionally more sophisticated studies may be needed (e.g., arterial blood gas, maximal voluntary ventilation, reproducible spirometry, and graphs etc.)
4. The objective of classification according to pulmonary capacity, as in other functional categories, is to allow as much latitude as is consistent with the safe operation of a motor vehicle.
5. The basic function tests (FVC and FEV1) are the principal guidelines and standards currently recommended.  These are subjective/objective tests.  When they are required, three graphs should be made and every effort should be made to elicit the full cooperation of the examinee.  A bronchodilator may be used if the examiner feels it is safe and justifiable.  The best reading, with or without bronchodilators, should be used.
6. In more severe cases of pulmonary impairment, measurement of arterial blood gas may be needed.  If there is a need for arterial gas measurements, the applicant usually would not qualify for Safety Assessment Levels 1 through 4, but the arterial blood gas determinations may support a different functional level than might otherwise appear indicated.  They may also help in defining safety assessment levels appropriate to limited private driving.
7. A driver who petitions DLD to remove an ignition interlock restriction due to inability to provide a deep lung breath sample requires a medical panel evaluation under this category and shall provide additional documentation, which includes pertinent medical history with reproducible spirometry and graphs. Arterial blood gas measurements may be required, especially if supplemental oxygen is needed.
8. COMMERCIAL INTRASTATE DRIVERS: A commercial intrastate driver
   meeting the requirements of Safety Assessment Level 4 will qualify for a license to drive commercial vehicles within the state boundaries.  Assessment Level 4 requires a yearly re-evaluation.  If supplemental oxygen is required, even intermittently during driving, the driver will be limited to a Class D license with no K restriction allowed.

NOTE: Regular and/or commercial intrastate drivers using supplemental oxygen for treatment of sleep disorders are considered separately.  See Category K.