Effect of smoking on hearing loss in refractory's factory male worker with occupational noise exposure in Iran

Objective: To assess the effect of smoking on hearing loss in factory workers with occupational noise exposure. Methods: This cross-sectional study was conducted at Birjand University of Medical Sciences, Birjand, Iran, from May to July 2013, and comprised smoking and non-smoking factory male workers. All of them were exposed to occupational noise level more than 85 decibels for at least 10 years. All participants underwent audiometric testing. SPSS 15 was used for data analysis. Results: Of the 150 participants, 55(36.7%) were smokers and 95(63.3%) were non-smokers. The mean age of the participants was 43.26 +/- 7.81 years while the mean working experience was 15.51 +/- 3.87 years. Furthermore, 18(32.7%) of the smokers and 8(8.4%) of the non-smokers suffered tinnitus (p=0.07). The mean noise intensity in the working place of the individuals was 892.63 A-weighted decibels. At a frequency of 500 Hz, the mean hearing loss was 4.8 +/- 5.7 decibels among smokers and 3.3 +/- 4.6 decibels among non-smokers in the left ear (p=0.52), whereas it was 4.8 +/- 5.1 decibels and 3.00 +/- 4.5 decibels in the right ear (p=0.15). The difference between the smokers and the non-smokers was significant in both ears at 1000Hz, 2000Hz, 4000Hz and 8000Hz (p<0.05 each). Conclusion: Smoking had an additive role in hearing loss among workers who were in close contact with excessive noise exposure.