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[Epidemiology of occupational respiratory diseases].

In the occupational environments air pollutants may be of different natures (chemical, mineral, etc.) and forms (particles, gas, etc.). Except in some acute circumstances the respiratory diseases need several years to develop. These diseases may be specific, caused by a particular pollutant (i.e.: silicosis, asbestos) or non specific (i.e.: chronic bronchitis). Epidemiological studies are well-adapted tools for the acquisition of knowledge and understanding of the pathological processes. They may also lead to efficient preventive action, treatment or compensation. For each of these 3 points (knowledge, understanding, action) one must keep in mind specificities of the respiratory diseases which may be different from one to the other with respect to etiological factors, varieties of disordered structure and function. One also must keep in mind the specificities of the place where the studies will be conducted (large or small factories, professional groups, specific or miscellaneous hazards), the research teams with different skills and competences, the relational problems with the managers, the workers, the unions, the occupational physician, etc. Some particular comments are given about the definition of the disease, the ways of examination methods, the population to be studied and controlled, the evaluation of hazards, the relationships between disease and risk factors.