<unk>  can result from a variety of causes, including infection with bacteria, viruses, fungi, parasites, and chemical or physical injury to the lungs. The etiology will depend upon various factors such as age, immune status, geographical area, and comorbidities.
Pneumonia causes
Cough causes
Aspiration pneumonia causes
Bronchiolitis causes
Bronchitis causes
Rhinitis causes
Pulmonary edema causes
Airway obstruction causes