Abstract
Nasal nitric oxide (nNO), discovered in exhaled air in 1991, is produced in the nose and paranasal sinuses. This small gaseous molecule plays various roles in the organism, e.g. the first line defense through its antiviral and antimicrobial activity, stimulation of ciliary motility, regulation of pulmonary function. The measurement of nNO has become a diagnostic tool in various diagnoses, such as primary ciliary dyskinesia, allergic rhinitis, chronic rhinosinusitis, and others. In this article, we discuss the potential benefit of nNO measurement in diagnosis and monitoring of various respiratory diseases.