Urban atmospheric levels of allergenic pollen: comparison of two locations in Salamanca, Central-Western Spain.

In this paper, differences in the pollen levels detected in two parts of Salamanca (a city in central-western Spain) have been revealed using two volumetric samplers. One sampler was located in the city centre and the other in a semi-natural zone. The two sampling devices were separated by a distance of 1.4 km. During the two-year study period, the most abundant allergenic pollen type was Poaceae, with peak values being detected in May. Maximum values were registered between April and June. The values obtained in both zones with regard to pollen seasonality were similar during the peak day, but the abundance of pollen grains detected in the semi-urban was higher, except for Olea pollen type. The atmospheric pollen season was similar in duration, except for some types belonging to the genera Plantago and Urticaceae, which showed divergent values most probably due to the influence of climatic conditions. The meteorological parameter most significantly correlated to pollen concentration was temperature, being negative for winter species and positive for plants preferring warmer climates. In addition, rainfall showed a negative correlation in most cases due to the influence of precipitation on the behaviour of atmospheric airborne pollen.