Assessment of noise-induced hearing loss in the staff of Yazd Airport, 2010-2011

Noise-induced hearing loss (NIHL) is a complex disease caused by interaction of genetic and environmental factors. Airport environment، as a source of noise، imposes loud noise on its staff and adjacent inhabitants. The aim of this study was to determine frequency of NIHL in staff of Yazd (Shahid Sadoughi) Airport in 20I0-2011. In this descriptive study، 106 subjects were collected by consecutive sampling from different parts of the airport. Three types of classification were applied، on the basis of workplace noise intensity، employment years، and daily work hours. Auditory status was assessed by pure tone audiometry. Workplace noise levels were also measured in flight and non-flight situations. The airport noise was intermittent and its intensity exceeded 85 dB in some situations. Among flight situations highest intensities were recorded respectively at the time of «on the runway»، «ready to fly»، descent «and» ascent «Among non-flight situations،» electricity generator «،» siren of ground security «and» flight guidance consul«had intensities higher than flight situations. (Respectively 109،103، and 94. 4 dB) Regarding pure tone audiometry، significant decrease of hearing threshold was more frequent at 4، 6 and 8 kHz (i. e. 8. 7%، 14. 6% and 18. 4% respectively in right ear، and 13. 2%، 21% and 16. 2% respectively in left ear). Thirty three percent of staff had NIHL. NIHL rate was higher in exposed subjects than non-exposed ones (42. 1% vs. 28. 9%; P-value=0. 039). Although، employment years had a significant impact on NIHL (p<0/001)، daily work hours had no effect. Airport environment noise caused hearing loss among airport staff، although it exceeded non-hazardous level only in few conditions.