Dynamic and Behaviour of Plane Tree Pollen and Its Relationship with Pla a 1 Aeroallergen Concentration in Évora, Portugal - European Medical Journal


Dynamic and Behaviour of Plane Tree Pollen and Its Relationship with Pla a 1 Aeroallergen Concentration in Évora, Portugal

| Allergy & Immunology
Ana Galveias,1 Beatriz Lara,2 Marta Otílio,1 Ana R. Costa,1 Ana Burgos-Montero,2,3 Jorge Romero-Morte,2 Jesus Rojo,2 Rosa Perez-Badia,2 *Célia M. Antunes1

The authors have declared no conflicts of interest.


This work received the support of the Portuguese Foundation for Science and Technology (FCT) through the ICT (Institute of Earth Sciences) project UIDB/04683/2020, the Pollensorb Project (PTDC/ATPEAM/0817/2014), the Spanish Ministry of Science, Innovation, and Universities through the project SICAAP-CPI RTI2018-096392-B-C22, the UCLM through the UCLM Plan Propio, the Castilla-La Mancha Regional Government, the European Social Fund (ESF), and the Youth Employment Initiative (YEI) for the postdoctoral grant for Dr Lara.

EMJ Allergy Immunol. ;5[1]:43-44. Abstract Review No. AR4.

Each article is made available under the terms of the Creative Commons Attribution-Non Commercial 4.0 License.


Platanus pollen is an important cause of allergy in many cities of western Europe, where this pollen is produced by the plane tree, Platanus orientalis L. var. acerifolia Dyand (Aiton), which is widely used as an ornamental species in parks, gardens, and other urban green areas,1 favouring human exposure to its pollen. Its major allergen Pla a 1 is recognised by up to 92% of monosensitised Platanus allergic patients and 83% of polysensitised patients, allergic to this pollen type, present 60% of IgE to its major allergen Pla a 1.2 In this study, the authors studied this pollen type and the allergen Pla a 1 in the year 2018 in the atmosphere of Évora, Portugal. The aim was to analyse the aerobiological characteristics of the Platanus pollen and to study the relationship between the airborne concentration pollen and the major allergen Pla a 1. Furthermore, the influence of meteorological variables on the airborne concentration of this pollen type was investigated.


Pollen and allergen sampling were performed using a Hirst-type spore trap (Lanzoni S.r.l., Bologna, Italy) and a high-volume cascade impactor ChemVol® (Butraco, Son, the Netherlands), respectively. Pollen was analysed following the procedure established by the European Aerobiology Society (EAS) and following the approach recommended in Galan et al.3 Allergens were quantified using a specific ELISA method.4 The main pollen season was calculated as 95.0% of total annual pollen, obtained after removing 2.5% of the start and end of total annual pollen integral.5 Meteorological data were obtained from the Atmospheric Sciences Observatory (ICT), University Évora, Évora, Portugal.


The results indicate that the main pollen season of the Platanus pollen took place from March 28th to April 20th. The maximum concentration was recorded on April 1st with 619 pollen grains/m3. There were 16 days of allergy risk (>50 pollen grains/m3) for people with allergies, of which seven were considered as high-risk level (>200 pollen grains/m3).6 Regarding Pla a 1, the temporal profile coincided and a significant relationship between the concentration of airborne pollen and allergen was found (Spearman’s R=0.632; p<0.01). The mean pollen potency7  was 14.4±7.7 pg allergen/pollen.

The temperature, precipitation, and relative humidity (RH) were the meteorological variables that most influenced the airborne Platanus pollen in Évora; maximum temperature occurring 4–7 days prior to pollen release positively influenced pollen loads, while precipitation and RH, particularly 7–8 days prior to pollen release, had a negative influence (Table 1).

Table 1: Spearman´s correlation analysis between pollen and meteorological variables considering different time lags.

Lag-time is the number of days before the current day (t).



In summary, these results show that the allergenic load (Pla a 1) coincides with the presence and magnitude of the pollen concentration in the atmosphere. Only the meteorological conditions during 4–8 days prior to pollen release were significant, suggesting that the environmental conditions during the pollen maturation process in the anthers are key factors involved in the Platanus pollen and allergen emissions and, thus human exposure to its allergens. Finally, the results suggest that pollen counts are good indicators of the allergenic loads in the atmosphere and, together with meteorological conditions, are useful to design allergen forecasts and alert systems for the allergic population.

Lara B et al. Prediction of airborne pollen concentrations for the plane tree as a tool for evaluating allergy risk in urban green areas. Landsc Urban Plan. 2019;189:285-95. Asturias et al. Purification and characterization of Pla a 1, a major allergen from Platanus acerifolia pollen. Allergy. 2002;57:221-7. Galán C et al. Pollen monitoring: minimum requirements and reproducibility of analysis. Aerobiologia. 2014;30:385-95. Arilla MC et al. Development of a sandwich-type ELISA for measuring Pla a 1, the major allergen of Platanus acerifolia Pollen. Int Arch Allergy Immunol. 2005;138(2)127-33. Andersen T. A model to predict the beginning of the pollen season. Grana. 1991;30:269-75. Galán C et al., “Intrepertation of results. Pollen count classes. Biological air quality. Publication of information”, Spanish Aerobiology Network (Rea) (eds), Management and Quality Manual (2007), Córdoba: Servicio de publicaciones de la Universidad de Córdoba, pp. 45-48. Alcázar P et al. Detection of airborne allergen (Pla a 1) in relation to Platanus pollen in Córdoba, South Spain. Ann Agric Environ Med. 2015;22(1):96-101.