A multidisciplinary study conducted by the Aerobiology and Physical Systems Modeling and Simulation research groups at the University of Cordoba has verified how the pollen season of grasses, a family of plants made up of thousands of species, and whose pollen is the most frequent cause of respiratory allergies, has been getting longer. Specifically, almost 4 more days each year, as flowering begins earlier and ends later.
The team confirmed this after analyzing daily pollen concentrations spanning 23 years and correlating them with meteorological variables such as temperature, rainfall and, mainly, wind patterns.
Although the temperature and previous rains lengthen the pollen season, the team found that wind is a key factor in understanding day-to-day differences in the amount of this type of pollen in the air, and its origin. As researcher Herminia García Mozo states: "wind analysis is important to explaining the behaviour of pollen season characteristics."
This study analyzes wind behavior through the combined use of meteorological models and observations. By calculating air mass back-trajectories — a meteorological tool that estimates the prior path of an air mass through the atmosphere before reaching a given area — and using wind speed data, the team has characterized wind dynamics more comprehensively and confirmed how wind influences the two main phases of the pollen season differently: one prior to and one following the moment of peak pollen concentration in the atmosphere.
During the prior phase, winds tend to be mild, on average, and air masses travel short distances, which favors pollen accumulation near its source. In the later phase, however, the wind moves at higher average speeds, and the air masses travel further, which, combined with the concentration data, suggests contributions from more distant areas. That is, the wind helps to concentrate the pollen at the beginning and favors its transport/dispersion at the end of the pollen period.
Understanding that pollen dynamics change according to the phase of the season allows us to lay the foundations to prevent and manage allergy seasons more precisely. As researcher Miguel Ángel Hernández Ceballos explained: "in this study we are assessing the past to try to anticipate the future scenarios that we may encounter. The more years we study, the better we can track pollen concentrations and the relationship established between all the factors involved. This will allow us to establish scenarios and anticipate actions."
By determining these patterns and their variability it is possible to foresee whether a season will be more intense or last longer than usual. In this way, the alert systems for allergy sufferers can be improved, and preventive measures can be taken earlier.
Reference
M.A. Hernández-Ceballos, R. López-Orozco, M.J. Tenor-Ortiz, C. Galán, H. García-Mozo, "Wind dynamics drive the changes of the 2001–2023 grass pollen seasons in Córdoba (southern Spain)", Agricultural and Forest Meteorology, Volume 378, 2026, 110955, ISSN 0168-1923, https://doi.org/10.1016/j.agrformet.2025.110955 .
