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

Background: Environmental factors are important causes of sensitization, ev en though the effect of specific pollutants and the interaction between pol lution 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 chil dren living in a rural area, ages 11 to 14, were studied. All subjects unde rwent a skin prick test. The pollen counts were performed in the two differ ent 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 highe r percentage of sensitization than those in the city (P =.046). Sensitizati on to pollen was more frequent in the rural area (P <.001) but pet sensitiz ation was more frequent in the city. More rural area students were sensitiv e to multiple allergens (P =.034), Pollen levels were higher in the rural a rea (P =.001). Both ozone and suspended particulate levels were higher in t he city (P =.001 and P <.001, respectively). Conclusions: The degree of pollen exposure is a larger contributing pathoge nic factor in inducing sensitization than air pollution.