Cigarette smoking and occupational noise-induced hearing loss.

BACKGROUND Noise is the most common occupational hazard. Noise-induced hearing loss (NIHL) is a known occupational disease. The economic costs of NIHL have been estimated to be billions of dollars. Besides, cigarette smoking is a common habit worldwide. METHODS In a cross-sectional study, we surveyed the effect of smoking on NIHL in 504 workers in a large wagon manufacturing company exposed to noise >85 dBA. All required data were obtained using direct interview and questionnaires. To determine noise exposure level, we used industrial hygienist's reports of sound level measurements. A qualified audiologist assessed hearing status using standardized audiometric examination. RESULTS We concluded that the frequency of hearing loss in smokers was higher than non-smokers [based on Model 1: odds ratio (OR) = 9.35, 95% confidence interval (CI) = 5.74-15.22 and P-value < 0.001; and based on Model 2: OR = 9.06, 95% CI = 5.93-13.84 and P-value < 0.001]. Besides, these results were confirmed by logistic regression statistical method. CONCLUSIONS It can be concluded that smoking may accelerate NIHL, but for confirming this opinion, further studies are warranted.