RESUMO
Serous otitis is due to eustachian tube dysfunction and accumulation of fluid in the middle ear cavity. Otitis media with effusion [OME] is common among children and can cause hearing loss. Smoking is a common predisposing factor of this condition. The present study was conducted with the aim of determining the effects of smoking on the prevalence of OME among children residing in urban area of Tehran between 1996 and 1998. This cross-sectional study performed on 3833 pre-school and school-aged children which their age ranged from 2 to 11 years. Children were examined with pneumatic otoscope and tympanometry was performed; meanwhile, their parents were asked to complete a questionnaire. The incidence of OME was 9.1% and 14.1% in pre-school and school-aged children; respectively, and was higher among children with smoker parents. Parental smoking is a preventable predisposing factor for OME; meanwhile, there are significant statistical differences between healthy and sick children regarding their parents pack-years smoking