Objective To observe the adverse effects of occupational hazards in machinery manufacturing industry on workers' nose and pharynx.

Methods Totally 2 014 male workers employed more than 1 year in a machinery manufacturing enterprise in Guangzhou were investigated. The workers were divided into different groups according to their occupational exposure history, namely reference group (733 workers, without any records of occupational hazards exposure or only noise-exposure), the dust-exposed group (619 workers, exposed to welding fume, manganese dust, cotton dust, grinding wheel grinding dust, and organic dust), and chemical-exposed group (622 workers, exposed to automobile exhaust, dimethyl benzene, and gasoline). The prevalence of chronic rhinitis and pharyngitis was compared among them and potential factors were analyzed.

Results The prevalence of chronic rhinitis was 13.6% (84/619), 9.8% (61/622)and 13.1% (101/773), respectively in the dust-exposed group, chemical-exposed group and reference group. There was no statistically significant difference among those groups (P>0.05). The prevalence of chronic pharyngitis was 69.1% (428/619) and 64.7% (402/622), respectively in the dust-exposed group and the chemical-exposed group, which was significantly higher than that(42.3%, 327/773)in the reference group (P>0.05/3). Multivariable logistic regression analysis showed that dust and chemical exposure were not related to chronic rhinitis, while dust exposure (OR=2.801, P < 0.01) and chemical exposure(OR=2.362, P < 0.01) were the risk factors of chronic pharyngitis. Compared with the age of 18-29 years old, the age of 30-39 years old (OR=1.361, P < 0.01), 40-49 years old (OR=2.444, P < 0.01)and 50-60 years old (OR=2.444, P < 0.01) were the risk factors of chronic pharyngitis. Occasionally smoking, frequently smoking and occasional drinking were the risk factors for chronic pharyngitis (OR=1.707, 1.324, and 1.778 respectively, P < 0.05).

Conclusion Occupational exposure to dust and chemical hazards were the important risk factors of chronic haryngitis. Correctly and reasonably using protective equipment is the important measure to reduce damage of occupational harmful factors on the pharynx. Further research on the effects of drinking on workers' nose and pharynx is necessary.