Trend analysis of aerobiological indicators associated with allergenic pollens in Emilia-Romagna, Northern Italy

This study is related to an overall analysis of the most relevant pollen season modifications as they emerge from the aerobiological monitoring activity in the network of stations in Emilia-Romagna, a region located in Northern Italy. The taxa selected for the study are among the most important from an allergenic point of view. The selected period goes from 1991 to 2017 in order to have a similar length for all the different taxa in all the stations, regardless of their date of activation. Statistical analysis of the time series of some pollen season indicators has been carried out in the period, with the aim of pointing out the most relevant changes in the ensemble of the monitoring stations. The available database lasting more than 25 years can be the basis for a robust statistical analysis of the long-term trends in the time series of pollen seasonal indicators. The stations are operating throughout the whole Emilia-Romagna territory, spanning a range of climatic conditions from the inner Po Valley to the coastal area. Results of the trend analysis indicate that the starting and the peak dates of the pollen season are in prevalent advance. This is true both for most herbaceous taxa, as well as for several arboreal ones. As for pollen production, a different behaviour characterizes herbaceous and arboreal taxa; in fact, a generally decreasing trend interests all herbaceous taxa, while a prevalent increasing trend is present in several of the latter. Pollen season indicators are certainly more directly affected by the changes associated with the meteo-climatic forcing and are possibly more influenced by climatic change.