title: Prevalence of Noise Induced Hearing Loss in Indian Air Force Personnel.
abstract: BACKGROUND
  Noise exposure is an inherent part of duty of the aircrew and maintenance staff in the Indian Air Force (IAF). An audiometric survey of IAF personnel was carried out to analyze the prevalence and severity of noise induced hearing loss (NIHL).
  
  
  METHODS
  An audiometric study of 1000 IAF personnel of various trades, age and exposure groups were carried out at an operational base. Age related correction of 5 dB per decade was applied for personnel above SO years of age. Personal factors like smoking, blood group and use of ear defenders were analysed for their effect on the prevalence of NIHL.
  
  
  RESULTS
  The study revealed an overall incidence of NIHL of 22.9 % in the personnel with a higher prevalence among the technical trades (26.18 %) as compared to non technical trades (12.5 %). There was a significant increase in prevalence of hearing loss with duration of exposure with 50.8% of personnel above 30 years of exposure having hearing loss. A higher incidence of hearing loss was observed in personnel of blood group O and smokers whereas use of ear defenders was protective.
  
  
  CONCLUSIONS
  The study reveals a significantly increased prevalence of NIHL among the technical trades of the IAF personnel. The deleterious effects of smoking and protective effect of regular use of ear defenders are emphasized.
authors.affiliation: Graded Specialist (ENT), Command Hospital (AF) Bangalore- 560007.
authors.forename: S
authors.initials: S
authors.lastname: Nair
authors.affiliation: PMO, HQ WAC IAF, Subroto Park. New Delhi.
authors.forename: R C
authors.initials: RC
authors.lastname: Kashyap
keywords: Ear defenders; Noise induced hearing loss; Smoking