(HealthDay News) – Roadside ragweed pollen exposed to pollution from heavy automobile traffic is more allergenic than pollen from similar plants found near less-traveled roads or in vegetated areas.

Alessandra Ghiani, of the University of Milano-Bicocca, and associates collected mature pollen grains from ragweed plants grown alongside roads and in vegetated areas of the Lombardy region in northern Italy to evaluate the effect of traffic-related pollution on the allergenicity of the plants.

The researchers found no statistical difference in the percentage of sub-pollen particle-releasing grains (SPPGs) among pollen samples evaluated by microscope and image analysis. Data indicated that the mean percentage of SPPGs after hydration was very low (<4%) in all samples. However, pollen collected along high-traffic roads showed a higher whole allergenicity level than samples from other regions of the Lombardy plain. The investigators attributed both quantitative and qualitative differences in allergen pattern to the higher allergenicity levels.

“Our results suggest that the effect of traffic-related pollution on sub-pollen particle release is species specific, and we cannot exclude that this is the case also for allergen expression and reactivity that could depend on the plant sensitivity to the single pollutants and on the reproductive plant organ and pollen structure,” the authors write. “Nonetheless, it is of great relevance that, at least for ragweed, the integrated action of traffic-related pollutants seems able to enhance pollen allergenicity, thus contributing to the rapid increase in sensitization rate.”

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