Effect of occupational exposure and smoking on spirometric tests and symptoms of chronic bronchitis

The importance of occupational exposure to airborne agents in the development of obstructive lung disease is uncertain. The aim of the study was to evaluate the effects of smoking and of occupational exposure on the lung function and chronic respiratory symptoms. I studied a group of 1239 adults (766 men and 473 women; mean age 44.9 +/- 8.6 yrs; current smokers 42.1%, lifetime nonsmokers 41.6%) working in 5 factories in the Bielsko-Biala area. Simple spirometric test (FEV1, FVC, FEV1%FVC) and a questionnaire on chronic respiratory symptoms, smoking habits and occupational exposures were applied. Respiratory symptoms and lung function were studied in relation to years of occupational exposure and adjusted for smoking habit. Occupational exposure was reported by 35.7% (n = 442) participants (dust 20.6%; gases or fumes 27.6%; mixed exposure 51.8%), with a mean duration of 20.9 +/- 9.2 years. In all cases concentrations of noxious agents did not exceed allowed levels. The symptoms of chronic bronchitis (cough and phlegm) were present in 12.3% and airflow limitation (FEV1% FVC < 0.7) in 6.9% of subjects. The significant relation of respiratory symptoms and bronchial obstruction to smoking was confirmed. No significant association between occupational exposure and ventilatory function or respiratory symptoms was found in a whole group. Smoking--specific analysis showed that current smokers appeared to be more susceptible to the effects of professional exposure. It was expressed in lower lung function indices and significantly higher odds ratios for airflow limitation or chronic respiratory symptoms for smokers exposed compared to nonexposed. Sufficient evidence of health selection processes known as a "healthy smoker" and a "healthy worker" effects were revealed.