The Impact of Climate Change on the Spread of Airborne Pollen in Northern Italy - The Results Of 27 Years of Monitoring in Parma

Pollen grains play an important role in the etiopathogenesis of seasonal respiratory allergies, which are increasing in prevalence and severity worldwide. Climate change is one of the possible explanations for the increase of pollen allergies enabling plants to produce more allergenic pollen, in larger quantities and longer periods. Pollen count data can be considered the proxy for aeroallergen exposure and long pollen data sets allow to investigate the trends in seasonal characteristics over time. This study examines temporal variations in seasonality and load of airborne pollen and meteorological data recorded over 27 years in Parma (Italy). The study was performed collecting pollen by a Hirst spore trap considering the following taxa: Betula, Corylus, Cupressaceae-Taxaceae, Platanus, Ambrosia, Poaceae, Total pollen and Alternaria fungal spores. Start and end date, duration, date of peak, peak value, and Seasonal Pollen Integral (SPIn) were examined. Temporal variations in pollen seasons were displayed as the number of days from January 1 (DOY, day of the year). Daily averages temperature, relative humidity and total rainfall were considered. Linear regression analysis was carried out to investigate trends in data over time. The start date turned precocious for Corylus and Poaceae, but late for Betula. The end date was postponed for Poaceae and Total pollen, as well the duration of pollen seasons was longer for Poaceae and Total pollen, the duration became shorter for Betula. The peak date was anticipated for Poaceae, and the peak values were reduced for Poaceae and Total pollen. A weak positive trend was observed for SPIn of Corylus. Regarding Ambrosia, the duration was shorter, and the peak date was postponed. No significant differences were observed for Platanus and Alternaria spores. A significant decrease in the relative humidity and a significant increase of annual average temperature were observed. The results of our study represent a contribution to better understanding the impact on human health of environmentally changing conditions. Moreover, it should be considered that not only the seasonal respiratory allergies may be related to the variation of climate and its impact on pollen load and pollen season, but also it could be related to chronic respiratory disease and cardiovascular diseases. This highlights gaps in current knowledge and the need to quantify the impact of climate change in a One Health perspective to provide useful information to determine exposure of the allergic population to pollen and to plan public health preventive measures.