Comparison of results derived from follow-up examination of respiratory systems in chosen groups of metallurgists.

In a 16.5-year follow-up study of the steel industry we investigated the relation of chronic occupational exposure to the changes of ventilatory efficiency and to the frequency of chronic bronchitis (Chronic Obstructive Pulmonary Disease--COPD) in a group of 65 men working in the harmful environment of a Coking Plant (CP). The reference group comprised 34 employees of Cold Rolling Mill (CRM) working in favorable hygienic conditions. The faster decline of VC and FEV1 were noted in the group of CP in comparison to the control group. Also the frequency of pathologic values of RT was significantly higher (p < or = 0.001) in the exposed group. The incidence of COPD increased more in the group of CP than in the group of rollers. No differences in the annual decline of FEV1 and VC between smokers and nonsmokers from CP were noted, while in the group of men working in favorable environmental conditions the differences between smoking categories were significant. It suggests that the impact of occupational exposure is so powerful that it can mask the unfavorable influence of cigarette smoking on the ventilatory function of men working in a Coking Plant.