A simple test of nasal mucociliary clearance is to place a small particle of saccharin approximately 1 cm behind the anterior end of the inferior turbinate. In the presence of normal mucociliary action, the saccharin will be swept backwards to the nasopharynx and a sweet taste perceived.
Failure of sweetness to be detected within 10-20 minutes signifies delayed mucociliary clearance. Referral to a specialist chest physician is then required as without appropriate management, these patients may be at risk of developing irreversible lung damage.
Further investigation of delayed clearance is usually in the form of photometric examination of brushings of the inferior turbinate.