Effect of cigarette smoking on nasal mucociliary clearance: A comparative analysis using saccharin test

BACKGROUND: Nasal mucociliary clearance (NMC) system transports the mucus layer covering the nasal epithelium towards nasopharynx by ciliary beating at a frequency of 7-16 Hz. NMC is altered by septal deviations, upper respiratory infections, and drugs. Few studies have revealed significant depression of ciliary activity in smokers. We conducted this study to compare NMC and influence duration of smoking on NMC in adult smokers and nonsmokers using saccharin test. MATERIALS AND METHODS: Our study included 30 nonsmokers and 30 smokers (21-40 years) who were not on any medications and had no history of any systemic illness. Time elapsing until the first experience of sweet taste at posterior nasopharynx, following placement of saccharin particle approximately 1 cm behind the anterior end of inferior turbinate was recorded as NMC time in minutes using standard method described by Anderson. Mean NMC of both groups were compared using Student's t-test and influence of duration was analyzed by one-way Analysis of variance (ANOVA). RESULTS: NMC was significantly prolonged in smokers (481.2 ± 29.83; P < 0.01) in comparison to nonsmokers (300.32 ± 17.42 s). A statistically significant increase in NMC was observed with an increase in duration of smoking habit (NMC in smoking <1 year = 492.25 ± 79.93 s, 1-5 years = 516.7 ± 34.01 s, >5 years = 637.5 ± 28.49 s; F statistic = 20.8968, P = 0.0000). CONCLUSIONS: NMC measurement is a simple and useful index for the assessment of effect of smoking on the ciliary activity of respiratory mucosa. Prolonged clearance observed in smokers of our study may be due to slowed ciliary beat frequency or reduction in number of cilia and changes in viscoelastic properties of mucus.