The allergen load: the impact of co-exposure to high concentrations of pollen and fungal spores in Italy

Seasonal respiratory allergies are a public health concern increasing worldwide. Airborne pollen and fungal spores are the main allergenic agents triggering reactions in sensitized individuals. Up to 80% of patients who seek help from allergy specialists are polysensitized. Climate change alters the seasonality, load, and allergenicity of pollen. This study aims to quantify the co-exposure to high concentrations (exceeding the thresholds of the risk of exposure for each taxon) of allergenic pollen and Alternaria sp. in Italy. The OpenData of the Italian Aerobiological Monitoring Network, were examined analysing the mean of total number of days per year with co-exposure to high concentrations and the number of allergenic taxa involved. Statistical analysis was performed to assess trends and differences between stations by geographical and climatic areas. The results reveal that co-exposure to high concentrations of airborne allergenic taxa is a recurring event in Italy, reaching frequencies of 30% of days/year in some areas, with significant differences between geographical regions. Bologna, Bolzano e Florence recorded up to six different pollen species at high concentrations on the same day. Parma showed the maximum level of days of co-exposure with 7.8 days to four taxa, to Plantaginaceae-Poaceae (53.5 days) and Plantaginaceae-Alternaria (60 days). The lowland recorded a higher number of days of co-exposure to high concentrations between pollen (Seaside-Lowland p = 0.0016, Lowland-Hill_mountain p = 0.0125 and between pollen and Alternaria (Seaside-Lowland p = 0.0007, Seaside-Hill_mountain p = 0.0175). These findings highlight the need for public health interventions through a multidisciplinary approach and a One Health perspective to mitigate the impact on affected individuals.