RESUMO
Mass screening diagnosis of the workers and employees engaged in nickel industry of the Noril'sk industrial region (n = 3049) according to the clinico-epidemiological program of the All-Union Research Institute of Pulmonology demonstrated a high incidence of chronic bronchitis (CB) and its preclinical conditions. The persons at risk for CB accounted for 41.5%, for prebronchitis for 23%, and those with CB for 19%. Among men, CB and its preclinical forms were demonstrable at a greater rate (63.7%). The disease prevalence depends on the time of residence in the Extreme North. Irregularity of the disease prevalence among different occupational groups is determined not only by the industrial and hygienic working conditions but also by the whole complex of ecological factors of the extreme region.