The nose filters, moistens, and warms inspired air at rest and during activity. Exercise is associated with an increase in nasal airflow and a decrease in resistance to that flow. Mechanistically, changes in the nasal mucosa during exercise may increase neutrophilic infiltration, impair olfaction, and prolong mucociliary transport time. The increased exposure to substances in the exercise environment may also produce rhinitis. Clinically, the prevalence of rhinitis and upper airway infections is increased in athletes. Allergic and non-allergic rhinitis, and rhinosinusitis may be diagnosed clinically, with other studies supporting the diagnosis; their main treatments are topical steroids, antihistamines, and saline.