Large variations in the development of chronic airway disturbances in the population have been uncovered, together with possible increased risk of such disturbances. There seems to be a connection to exposure to pollutants at work and in home environment. The interconnection and interaction between irritants, allergens, infectious agents and other biologically active substances may have a decisive impact on the risk an individual runs of developing chronic suffering in the upper and lower respiratory tract. Injuries in mucous membranes and airways, connected with the development of unspecific hyperreactivity may play a central role in the development of allergic and nonallergic airway disturbances and diseases. These findings may have a decisive influence on the choice of prophylaxis and therapy.