We will mention only the most prominent ones, in the upper respiratory tract and, on the next page, in the lungs.
Inflammations of the nasal mucosa are of course all (unfortunately) well-known and common. Usually caused by a virus.
Septal deviation. In some people, the septum can become crooked, either congenitally or due to trauma. That of course prevents normal airflow.
Sinusitis; inflammation in one of the sinuses connected to the nose. Very annoying!
Nodules (epithelial proliferations) can also occur on the vocal chords , especially in (professional) singers, due to overloading.
Paralysis of the vocal cords can also occur, usually caused by paralysis of the nerve supplying it (recurrent laryngeal nerve). Usually only on one side (left or right) so that the patient sounds hoarse but can still talk.
