(1) No objective findings are present. Subjective complaints may be present or absent.

(2) Objective findings of one or more of the following air passage defects: Partial obstruction of oropharynx, laryngopharynx, larynx, trachea, bronchi, complete obstruction of nasopharynx or of nasal passages bilaterally. No dyspnea caused by the air passage defect even on activity requiring prolonged exertion or intensive effort.

(3) Objective findings of one or more of the following air passage defects: Partial obstruction of oropharynx, laryngopharynx, larynx, trachea, bronchi, complete obstruction of nasopharynx or of nasal passages bilaterally, dyspnea caused by the air passage defect produced only by prolonged exertion or intensive effort.

(4) Objective findings of one or more of the following air passage defects: Partial obstruction of oropharynx, laryngopharynx, larynx, trachea, bronchi, complete obstruction of nasopharynx or of nasal passages bilaterally, with permanent tracheostomy or stoma, dyspnea caused by the air passage defect produced only by prolonged exertion or intensive effort.

(5) Objective findings of one or more of the following air passage defects: Partial obstruction of oropharynx, laryngopharynx, larynx, trachea, bronchi, with or without permanent tracheostomy or stoma if dyspnea is produced by moderate exertion.

(6) Objective findings of one or more of the following air passage defects: Partial obstruction of oropharynx, laryngopharynx, larynx, trachea, bronchi, with or without permanent tracheostomy or stoma if dyspnea is produced by mild exertion.