An Investigation into the Effects of Hearing Loss and Hearing Impairment on Rebar Production Unit Workers of Kerman Steel Industries

Acute hearing loss due to noise and hearing impairment is one of the most common occupational diseases which imposes significant direct and indirect costs on the government and exposed individuals. The steel industry is one of the industries that a great deal of noise is produced in different parts of its working process. Therefore, in this research, we tried to investigate the relationship between noise exposure and permanent hearing loss due to noise, as well as hearing impairment among employees of rebar production unit in Kerman Steel Industries.
In this descriptive-analytic study, two methods of bioassay and environmental monitoring were used. In bioassay method, seventy one workers of the production line audiology condition, which was selected by census method, were tested and in the environmental monitoring, sound state of the production sector was measured and evaluated. Also, using a questionnaire, their personal information and work experience were recorded.
From the 71 workers surveyed, 20% were between 25-30 year old, 70% aged 30-40 years old, 10% were more than 40 years old, 63% had a work experience of 1-5 years and 37% had work experience more than 5 years. Comparison of the sound pressure level with the permissible national standard states showed that in 93% of the measured points, the sound pressure level was higher than standard, and the results of the audiometric data showed that in 55% of individuals, the hearing threshold in the right ear at a frequency of 4000 Hz has risen above 25 dB, and this value is 46% for the left ear.
Considering that the increase in hearing thresholds at 4000 Hz is the main symptom of hearing loss due to working in industrial environments, we can conclude that taking control measures is very necessary. The percentage of auditory hearing impairment in the left, right and both ears is less than 10% and this can be attributed to the worker's work experience.