Environmental factors associated with variation in airborne pollen concentrations revealed by automated aerobiological measurements

The impact of meteorological factors and air pollution on the dynamics of allergenic pollen dispersal was investigated in this study using automated monitoring data. In 2022-2024, pollen concentration data for Alnus, Betula, Corylus, and Poaceae collected in Vilnius (Lithuania) using an automated bioaerosol measurement device were applied to analyse not only pollen seasonality (start, end, and length) but also correlations with meteorological variables and air pollution. A 40-day pre-season window was used to investigate the effects of pre-season meteorological conditions on changes in pollen concentration and seasonality. The study revealed that the Betulaceae family (including Alnus, Betula, Corylus) pollen season started earlier than the Poaceae family, but was shorter (82 days on average), while the Poaceae family had the longest season (93 days on average). Pollen concentrations increased between 2022 and 2024. The study found statistically significant positive correlations linking air temperature and hourly pollen concentrations (Betula: r = 0.39 to 0.62, p < 0.01; weaker with other pollen types) and negative correlations with relative air humidity (Betula: r = −0.47 to −0.67, p < 0.01; weaker with other pollen types), while the effect of precipitation, wind direction and wind speed was mostly statistically weak. With respect to Betula and Corylus, pre-season meteorological conditions with higher air temperatures and lower relative humidity were associated with higher pollen concentrations, and for Corylus and Poaceae, they were associated with a longer season. Air pollution analysis revealed that pollen concentrations were more often positively correlated with PM, NOx and CO, but these relationships were not unidirectional and depended on plant taxa. This study enables automated pollen monitoring data to reveal relevant aspects of the statistical analysis of meteorological parameters and air pollution, as well as the dynamics of airborne pollen concentration.