Intradiurnal variations of airborne pollen in Sierra de las Nieves (southern Spain)

Abstract

Pollen was sampled by means of a Hirst-type volumetric pollen trap installed in ―Las Conejeras‖ recreational area. In this study, data from 2018 to 2023, both inclusive, were considered. The most relevant pollen types according to their frequent presence in the atmosphere and allergy interest were studied, i.e., Amaranthaceae, Castanea, Cupressaceae, Olea, Pinus, Plantago, Poaceae, Quercus and Urticaceae. Countings were made hourly, considering only days without rainfall with a daily mean pollen concentration equal to or greater than the mean of the main pollen season (MPS) (Galán et al., 1991). Then, accumulated values for every two hours were calculated, and the pollen detected was expressed as percentages over the daily total. Three different intradiurnal patterns were observed. Amaranthaceae and Urticaceae presented a similar pattern, with their highest presence during the last hours of the day; Castanea, Cupressacea, Olea and Pinus showed a peak after midday; and Plantago, Poaceae and Quercus pollen concentrations were evenly spread throughout the day. Pollen types integrated by numerous species (e.g., Poaceae or Plantago) tended to present lower peaks during the day while pollen types integrated by few species, such as Castanea, Cupressaceae or Pinus had more pronounced peaks. The period of the day with the highest pollen detection in the air was between 12 and 21 hours, with the greatest incidence between 12 and 13 hours. Conclusions. The different pollen types studied have presented different intra-daily behaviours, with the highest concentrations detected starting at midday and peaks of different intensity that, with some exceptions, normally take place between 12:00 and 14:00.