Background: Occupational noise is the most common hazards in the workplaces. Noise exposure may induce tinnitus (ringing in the ears), which seriously affects workers’ normal life, even impair their work performance. To investigate associations between if respondents are awareness of tinnitus induced by occupational noise (Knowledge), what the viewpoint they have (Attitude) and how they cope with it (Practice).
Methods: A questionnaire based cross-sectional study was conducted. 519 noise-exposed workers in railway transportation mechanical manufacturers were recruited as the exposed group. 515 non noise-exposed workers as the control group. To investigate the effects of noise exposure level, the exposed group was classified into 4 subgroups according to sound level measurements reported by industrial hygienists., while the exposed group was categorized into 3 subgroups according to usage of personal hearing protection device (PHPD). Questionnaire was focused on medical history, occupational history, life habits and tinnitus for all participants. Qualified audiologists assessed hearing threshold by using standardized audio-metric procedures assuring at least 48 h of noise avoidance.
Results: The prevalence of tinnitus were 36.6% and 18.8% in the exposed group and in the control group, respectively. The difference was statistically significant (c2=40.725, P<0.05). The prevalence of tinnitus were 36.2%, 20.5% and 41.7% in 3 using PHPD subgroups of the exposed group. The difference was statistically significant (c2=6.072, P<0.05). The prevalence of tinnitus were 34.7%,8.3%,63.6% and 54.0% in 4 sound level subgroups. The difference was statistically significant (c2trend=30.491, P < 0.05). The percentage of clinic visit for tinnitus was 15.8% in the exposed group. 93.2% workers claimed tinnitus symptoms were unimproved since they still heard buzzing or ringing in ears. 81.05% of them gave up treatment. The percentage of clinic visit for tinnitus was 7.2% in the control group and 99.0% workers claimed tinnitus symptoms were unimproved.
Conclusions: Only when workers have awareness of tinnitus and tinnitus treatment can they have positive attitude and better practice. Noise-exposed workers should periodically attend educational courses on “taking care of your ears” and should be under the supervision.