Changes in the pollen season dynamics in central Chile in the last 20 years

Abstract

Airborne pollen exposure is a major trigger of respiratory allergy, but long-term aerobiological series from the Southern Hemisphere remain scarce. We analyzed changes in the intensity, time and meteorological variables of major allergenic pollen types in Talca, a representative city of central Chile, over nearly two decades. Daily pollen counts from Hirst-type volumetric traps were obtained for three seasons (2007/2008, 2013/2014 and 2024/2025), and the annual pollen integral (APIn) and main pollen season (MPS) metrics were calculated for nine relevant taxa and for total pollen. The APIn increased by more than 240% between the first and last periods, with particularly marked rises for Olea, Cupressaceae, Poaceae, Corylus and several herbaceous plants. For many taxa, the MPS started earlier and/or ended later in 2024/2025, lengthening clinically relevant exposure windows, whereas Platanus and Populus maintained short but intense spring peaks. Cupressaceae showed an extended MPS of about six months, and Olea and Corylus exhibited sharp increases in seasonal totals consistent with recent expansion of nearby plantations. Temperature emerged as the main, though taxon-specific, driver of day-to-day variability, with Poaceae positively associated with temperature and solar radiation and negatively with relative humidity, while some arboreal taxa showed negative correlations coefficients with temperature. Our results indicate an intensification and extension of pollen seasons in the city of Talca. General implications for clinical and public‑health are discussed.