Abstract

CAEIRO, Elsa et al. The diurnal variation study of grass pollen concentrations in atmosphere of mainland Portugal. Rev Port Imunoalergologia [online]. 2013, vol.21, n.1, pp.27-40. ISSN 0871-9721.

Background: Airborne grass pollen is one of the main sources of aeroallergens in the world, particularly in the Mediterranean Europe. Grass pollen is an important risk factor for asthma, allergic rhinitis and/or conjunctivitis and it constitutes the main cause of pollinosis in Portugal. Objective: To analyze the diurnal variations of Poaceae pollen concentrations in the atmosphere of 5 monitoring stations: Oporto, Coimbra, Lisbon, Évora and Portimão. Methods: In this study, daily and hourly sampling data of Poaceae pollen from five monitoring stations over a seven year interval (2002-2008), were used. Results: Statistical significant differences were observed in hourly pollen curves. Grass pollen was recorded in the atmosphere during 24 hours in all the monitoring stations, with the lowest values recorded between 22 and 6 hours and the highest values between 7 and 21 hours, where in Évora more than 30 pollen grains/m3/hour were recorded. In general, there are 2 high peaks pollen: one in the morning (9-10 hours) or afternoon (12-13 hours) and the other in the evening / early night (19-20 hours). Conclusions: The diurnal rhythm is very different from each locality. The differences can be mainly explained by the different species of grass pollen existing in these areas and by the different environmental conditions. The exposition degree varies from station to station, and throughout the day. In Portugal, the risk of exposure to this pollen is lower in Oporto and highest in Évora.

Keywords : Aerobiology; diurnal variation; grass; Poaceae; Portugal.

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