The fact that allergic diseases increase in prevalence is a generally accepted and worldwide phenomenon. The causes for this increase are not known: only hypothetical concepts exist. Epidemiological studies comparing Eastern and Western European populations have shown a striking difference in the prevalence of respiratory atopic diseases, which is lower in the East. At the same time, different patterns of air pollution have been described, namely 'classical' type I, characterized by SO2 and dust prevailing in the East, and 'modern' type II, characterized by organic compounds, fine particles and
ozone, which is more prominent in the West. Type II was associated in multivariate regression analysis with increased prevalence of
IgE-mediated
allergy. Pollen grains collected from industrial regions with high polyaromatic
hydrocarbon load in West Germany, but not in East Germany, were shown to be agglomerated with airborne particles. In vitro exposure of pollen to particles indicated morphological changes and increased
allergen release from the pollen. In vitro exposure of pollen to gaseous
pollutants (SO2 and NO2) under different conditions of humidity resulted in SO2-induced, but not NO2-induced reduction of
allergen release from pollen. It is concluded that the bioavailability of grass pollen
allergens may be modulated by
air pollutants, supporting the concept of an interaction between pollen and
pollutants in the atmosphere outside the organism which in turn may affect
allergy-relevant phenomena.