Environmental pollution and allergy.

OBJECTIVES: Among the theories supporting the increase of allergic diseases in modern western countries during the last several decades is the concept that environmental pollutants may play a vital role. Reading this article will enable the reader to recognize the effect of different types of environmental pollution on the development, modulation, and persistence of allergic reactions. DATA SOURCES: Data sources include references to relevant articles and texts. To characterize the influence of environmental pollutants on allergic reactions (allergotoxicology), epidemiologic, clinical, and experimental data are considered.
RESULTS: The investigations show that air pollution patterns differ with respect to their effect upon allergies. Classical air pollution (type I) with high sulfur dioxide and dust particles seems not to be associated with allergic disease in humans. However, type II pollution characterized by elevation of oxides of nitrogen (NOx), ozone (O3), tobacco smoke, fine and ultrafine particulate matter, and diesel exhaust particles seems to enhance allergic disease.
CONCLUSIONS: The data suggest that environmental pollution can act at different levels and by complex interactions both outside and inside the individual and influence allergic diseases.