Differences in prevalence of allergic sensitization in urban and rural school children

Background: Environmental factors are important causes of sensitization, even though the effect of specific pollutants and the interaction between pollution and aeroallergens are not completely known. Purpose: To evaluate whether the exposure to pollutants or to allergens is a more important contributing factor in causing sensitization. Methods: A group of 312 children living in the city and a group of 225 children living in a rural area, ages 11 to 14, were studied. All subjects underwent a skin prick test. The pollen counts were performed in the two different areas during the peak of the pollen season. At the same time the levels of ozone and suspended particulates were measured. Results: The students living in the rural area showed a significantly higher percentage of sensitization than those in the city (P =.046). Sensitization to pollen was more frequent in the rural area (P <.001) but pet sensitization was more frequent in the city. More rural area students were sensitive to multiple allergens (P =.034), Pollen levels were higher in the rural area (P =.001). Both ozone and suspended particulate levels were higher in the city (P =.001 and P <.001, respectively). Conclusions: The degree of pollen exposure is a larger contributing pathogenic factor in inducing sensitization than air pollution.