Diseases of the mucosa of the upper respiratory tract have increased in the last few decades. In epidemiological studies, an increase in the rate of allergies has especially been noticed. The offensive particles from the environment meet human organism in the respiratory mucosa of the nose: the function of the mucosa depends partly on the protective function of the mucus, ciliae and swelling bodies of the mucosa and partly on the abundant number of immunocompetent effector cells in the subepithelial lamina propria. Of central interest are the mast cells, which initiate reactions by means of the exocytosis of mediators: the hyperergic, anaphylactic reaction and the hyper-reflectoric, anaphylactoid reaction. Environmental noxious agents (sulfur dioxide, nitrous oxides, ozone, carbohydrides and dust particles) influence in different ways the pathological reactions of the mucosa: they provoke inflammatory reactions through toxic and chemical-irritative effects. They lead to the initiation and perpetuation of allergies. This happens through the changing spectrum of allergen exposition, through direct changing of the surface and structure of proteins of the allergens and through the strengthening of the humoral and cellular mechanisms, which are part of the initiation and perpetuation of allergies. Environmental noxious agents initiate hyper-reflectoric reactions of the mucosa, which seems to be the most impressive factor causing the change in rhinological diseases nowadays. Environmental noxious agents are partially responsible for the "priming effects."