Seasonal variation in diurnal atmospheric grass pollen concentration profiles
- 1Department of Environmental Science, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
- 2National Pollen and Aerobiology Research Unit, University of Worcester, Henwick Grove, Worcester, WR2 6AJ, UK
- 3Department of Public Health, Aarhus University, Bartholins Allé 2, 8000 Aarhus C, Denmark
- 4Department of Oto-Rhino-Laryngology, Medical University of Vienna, Vienna, Austria
- 5Asthma-Allergy Association Denmark, Universitetsparken 4, 4000 Roskilde, Denmark
- 6Department for Environmental, Social and Spatial Change (ENSPAC), Roskilde University, Universitetsvej 1, 4000 Roskilde, Denmark
Abstract. In this study, the diurnal atmospheric grass pollen concentration profile within the Danish city of Aarhus was shown to change in a systematic manner as the pollen season progressed. Although diurnal grass pollen profiles can differ greatly from day-to-day, it is common practice to establish the time of day when peak concentrations are most likely to occur using seasonally averaged diurnal profiles. Atmospheric pollen loads are highly dependent upon emissions, and different species of grass are known to flower and emit pollen at different times of the day and during different periods of the pollen season. Pollen concentrations are also influenced by meteorological factors – directly through those parameters that govern pollen dispersion and transport, and indirectly through the weather-driven flowering process. We found that three different profiles dominated the grass pollen season in Aarhus – a twin peak profile during the early season, a single evening profile during the middle of the season, and a single midday peak during the late season. Whilst this variation could not be explained by meteorological factors, no inconsistencies were found with the theory that it was driven by a succession of different grass species with different diurnal flowering patterns dominating atmospheric pollen loads as the season progressed. The potential for exposure was found to be significantly greater during the late-season period than during either the early- or mid-season periods.