Advanced age
Altered level of consciousness
Anatomic abnormality of upper airway
Dementia
Esophageal disorders
Gastroesophageal reflux
Neuromuscular disease
Poor oral hygiene
Prior history of<unk> 
Prolonged supine position
Retained gastric material
Tube feedings
Aspiration pneumonia and pneumonitis
Pulmonary
High altitude pharyngitis and bronchitis
Airway obstruction
Immersion pulmonary edema
Anaphylaxis
Multisystem inflammatory syndrome in children
Angioedema