Effects of cigarette smoking and contemporary noise exposure on hearing loss

Both cigarette smoking and noise exposure have a common pathway to produce hearing loss. In this study, effects of cigarette smoking on hearing loss, in assembly line employees of one of the automobile plants in Iran, who were exposed to noise with more than permissible level, were examined. A case-control study was conducted in an automobile plant in order to assess the effects of contemporary exposure to excessive noise and smoking. Male workers of the assembly part were divided to cases (smokers) and controls (nonsmokers) groups. All workers were exposed to excessive noise. Hearing loss was defined in two models and effects of smoking on hearing loss were evaluated with statistical analysis. According to model 2, severity of hearing loss was higher in smokers group than nonsmokers group (odds ratio: 6.94; 95%CI: 4.54-10.64). Both models of hearing loss, even after adjusting for other variables, were significantly higher in smokers group (p<0.001). Smokers who are working in areas with excessive noise are more susceptible to noise induced hearing loss. So, their hearing system must specially be assessed in periodic exams.