Results of complex laboratory examination of 103 patients with dust related bronchitis caused by exposure of various industrial dusts, 22 patients with pneumoconiosis and 12 subjects not having respiratory pathology and not exposed to quartz dust or any other occupational hazards are presented in this article. Laboratory examination included morphological investigations of sputum and bronchial brush biopsy specimens, cytochemical characterization of bronchial ciliated epithelium and blood cells, and bacteriological and serological investigations of bronchial mucus. Our results demonstrated that morphological lesions of bronchial epithelium cells leading to their death followed cell dysfunction, disorders of enzyme activity, hypoxemia, predominance of Haemophilus influenzae in microflora, and significant inflammatory and allergic response in blood. These changes were found in different clinical stages of dust related bronchitis and pneumoconiosis. The findings obtained are of great importance for understanding pathogenic mechanisms of dust related lung diseases as well as from clinical point of view such as diagnosis and development of individual treatment strategies.