effect of excessive noise exposure on the hearing thresholds of aviation workers in Karachi

The purposes of this study on Aviation Workers were to [a] determine the prevalence of Noise induced hearing loss [NIHL] in aviation workers [b] suggest measures for its prevention. This cross sectional epidemiological study was conducted with noise exposed and non noise exposed matching variables of adult age group, full time [24 hours], male workers at a large metropolitan airport of Karachi, Pakistan [Noise exposed group], villagers living in the outskirts of Karachi who had their work place and residence within the village [non noise exposed group]. The three measures used were Hearing Questionnaire, Audiological assessment and a record review of base line hearing test [pure tone audiogram] and noise levels at locations of work and residence lived i.e. round the clock noise exposure. Subjects with other causes of hearing impairment like, otitis media, post high grade fever, metabolic disorders and history of ototoxicity were excluded from the study. A significant difference in prevalence of hearing loss [more than 30db] between the noise exposed and non noise exposed group [P<0.5] was noted. Aggressive hearing conservation measures are required for these aviation workers; they are like [a] Availability of HPD's [b] Ban on "Non Certified" aircraft operations as specified by ICAO Chapter 3, Annex-16

Audiometric findings in petrochemical workers exposed to noise and chemical agents.

This study investigated the occurrence of hearing loss among workers of a petrochemical industry during a period of five years. The records of environmental noise and solvents measurements and the results of annual audiometry performed by the company were examined. The audiometric results of workers from olefin operational areas 1 and 2 and aromatic plant areas exposed to solvents and noise and utility area workers exposed only to noise were analyzed for the standard threshold shift (STS). Despite the low exposures to solvents and a moderate exposure to noise, 45.3% of workers had hearing losses and 29.6% had STS.