The methodology of quantitative aerobiological control is described and the results of measurements of the intensity and character of air contamination are commented for several places of general surgical ward. The importance of such a control is stressed in the context of general efforts to improve the quality of air in hospitals, to prevent air contamination and decrease the incidence of aerogenic infections. The results of those measurements show that the intensity of air contamination is corresponding to the total volume of physical activity in a milieu. In some very delicate hospital areas (dressing units and operating theatres), the concentration of aerosol sometimes exceeds its permitted level and if this is a case, it is advised to take all possible measures of protection to prevent air contamination and aerogenic infections. It is also found out that at the very beginning of physical activity, there is predominance of relatively big aerosol fractions in air, but soon this predominance is diminished because of the elimination of those fractions by sedimentation.