Triennial monitoring of atmospheric pollen in Bragança, Portugal: identification of pollen types, behavior, and correlation with meteorological factors

Airborne pollen is a leading cause of allergic respiratory diseases and has significant impacts on public health and quality of life. This study presents aerobiological monitoring data from Bragança, Portugal, collected over three years (2022–2024) using a Hirst volumetric spore trap. The study aimed to identify predominant pollen types, quantify their intraday, seasonal, and annual variations, and evaluate their correlation with meteorological parameters. A total of 37 pollen types were recorded, with Quercus and Cupressaceae being the most abundant. Seasonal peaks were observed in spring, with secondary peaks in late summer and autumn. The concentrations of the most representative pollen taxa were compared with threshold limits found in the literature. Poaceae concentrations exceeded unsafe levels for sensitive populations on more than 60 days in 2024. Spearman's correlation analysis revealed significant positive associations between pollen concentrations and temperature and significant negative associations between pollen concentrations and relative humidity and precipitation. These findings establish a baseline for future aerobiological studies in the region and support the development of pollen forecasts and allergy prevention strategies.