Exposure to allergens represents a key factor among the environmental determinants of asthma. The most common information available for pollinosis patients is the concentration of pollen grains in the bioaerosol and their temporal distribution. However, in recent years, discordance between pollen concentrations and allergic symptoms has been detected. The purpose of this research is to evaluate the relationship between pollen counts and the atmospheric aeroallergen concentrations in different Spanish bioclimatic areas. For the monitoring of allergen content in the air, a quantitative antigen-antibody technique combined with the Cyclone sampling methodology was used. The study was conducted during 2007 by considering some of the most common allergens that induce pollinosis in each area: Platanus and Urticaceae in Ourense and Cartagena, and Poaceae in Ourense and León. In Ourense, pollen counts and aeroallergen concentrations coincided for the three pollen types studied, and the pollen and allergen data associated with the meteorological factors were highly significant for the pollen counts. In Cartagena (for Platanus and Urticaceae) and León (for Poaceae), the low correlations between pollen counts and allergen concentrations obtained could be due to the specific bioclimatic conditions. In contrast, the higher allergen concentrations found in the atmosphere in Cartagena and León compared to Ourense could be related to the existing pollutant levels there, inducing a higher expression of plant pathogenesis-related proteins in the plants of polluted cities. The combination of pollen counts and allergen quantification must be assessed to reliably estimate exposure of allergic people to allergens in different bioclimatic areas.

The presence of the aeroallergen Pla a 1 in the atmosphere appears to be independent of Platanus pollen counts over the same period, which may be contributing to allergic symptoms and sensitization. The number of polysensitized patients displaying allergy to Platanus suggested that allergic symptoms were caused by co-sensitization or cross-reactivity involving a number of allergenic particles.

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Winter-flowering trees such as the alder (Alnus glutinosa (L.) Gaertner) can survive periods of adverse climatic conditions, entering a period of dormancy in the early fall. The end of dormancy and the start of the pollen season require a period of low temperatures followed by another of warm temperatures. These requirements were studied from 1995 to 2002, in order to develop a model to predict the onset of the alder pollen season in Ponferrada (Spain). Chilling accumulation took place from late October to late December or early January. The best result was obtained with a threshold temperature of 6.5°C and an average of 848 chilling hours (CH). Heat requirements were calculated at maximum temperature, an average 143 growth degree days (GDD) were needed, with a threshold temperature of 0°C. In order to validate models, predicted values were compared with real values for 2002-2003, 2003-2004 and 2004-2005, years not used in developing the models. Predictions for the pollen-season start-date differed only slightly from observed dates: in 2002-2003 predicted and observed dates were the same, in 2003-2004 there was a difference of 7 days and in 2004-2005 a difference of 3 days.

The present study sampled pollen grains in the atmosphere using a Burkard Ò 7-day-recording trap and periodically checked the flowering phases of Plantago lanceolata L. in the locality of León (NW of Spain) from late March to early August during 2007 and 2008. The results showed that the phenological phases considered for P. lanceolata coincided in most sampling points. The differences between them depended mainly on the characteristics of the land on which the plants developed and water availability. In addition, the differences between the start and duration of the different phenological phases over the 2 years were mainly due to climatic variations each year. Plantago pollen concentration in the atmosphere and phenological data were related during these 2 years of study. The differences in Plantago pollen production per anther were determined by environmental conditions such as humidity. Another important factor was human action.