The Effect of Active and Passive Smoking on Hearing Loss in Noise-Exposed Metal Workers

BACKGROUND: Many people are exposed to cigarette smoke actively or passively. We aimed to determine the effect of active and passive smoking on hearing thresholds and hearing loss noise-exposed workers. METHODS: This cross-sectional study was conducted on 929 metal workers. We divided the workers into 3 groups according to smoking status—current smokers, nonsmokers, and passive smokers. Audiometric testing was recorded for both ears. Hearing loss was defined by 3 models. The SPSS software Version 24 was used to analyze the collected data. We used an independent t test, chi-square, Fisher exact, and analysis of variance tests and logistic regression, and the significance level was set at P ˂0.05 to interpret the relationships between variables. RESULTS: The hearing threshold levels at 4000 Hz, high frequencies, and low frequencies were significantly higher in smokers than nonsmokers (P < 0.05). Also, and hearing loss at the 4000 Hz (P = 0.002; odds ratio [OR] = 1.96; 95% CI = 1.27-3.03) and high frequencies (P = 0.001; OR = 2.15; 95% CI = 1.36-3.4) had a significant correlation with smoking. Hearing loss was significantly correlated with passive smoking at 4000 Hz (P < 0.001; OR = 5.87; 95% CI = 3.29-10.47), high frequencies (P < 0.001; OR = 7.16; 95% CI = 3.97-12.89) and low frequencies (P = 0.021; OR = 4.16; 95% CI = 1.12-15.43). CONCLUSION: The findings show that active and passive smokers who work in noisy environments are at higher risk for noise-induced hearing loss. Therefore, smoking cessation in smoker workers and reduction of environmental exposure to cigarette smoke is necessary to reduce the exacerbation of hearing loss. Moreover, more attention should be paid to passive smokers and they should be given priority in the same programs.