How to select the optimal monitoring locations for an aerobiological network: A case of study in central northwest of Spain.

Airborne pollen concentration varies depending on several factors, such as local plant biodiversity, geography and climatology. These particles are involved in triggering pollinosis in a share of worldwide human population, and adequate monitoring is, therefore, important. However, the pollen traps in aerobiological monitoring networks are usually installed in cities, and the features of the whole territory are not taken into account. The aim of this study was to analyze what environmental parameters are more suitable as regards setting up monitoring stations throughout a territory in order to obtain an aerobiological network that can represent environmental diversity. The analysis was carried out in 13 locations in Castilla y León over an 8 year period. This is a favorable territory in which to conduct this type of study owing to its climatic features, orography and biodiversity. The ten most abundant pollen types in the region were analyzed, and a clustering analysis was calculated with different distances so as to obtain homogeneous groups of stations. Moreover, the clusters obtained were analyzed in combination with altitudinal and different bioclimatic parameters, which derived from temperature and precipitation. The result here shows that the Castilla y León aerobiological network RACYL represents most of the environmental variability of the territory. Furthermore, it can be divided into two clusters and five sub-clusters for which the start of the main pollen season is different. This corresponds with the division of the territory as regards bioclimatic conditions. The most important bioclimatic parameters were the seasonality of the precipitation and the maximum temperature of the warmest month, although orography must also be taken into account. All of these help discover the optimal places in which to install traps and could reduce the number of monitoring stations. This study additionally provides data for unmonitored areas with similar bioclimatic conditions to those monitored.

Towards a model of wet deposition of bioaerosols: The raindrop size role.

Bioaerosols play a major role in the plant life of ecosystems. In addition, they have a profound impact on human health, since they may cause lung diseases or allergies. The key objective of this study is to assess the below cloud scavenging effect of rainfall on pollen concentration. The analysis is based on a sampling carried out in León, Spain, between 2015 and 2018. The rainfall variables and the pollen concentrations have been obtained with a disdrometer and a volumetric Hirst type spore-trap, respectively. In order to evaluate the scavenging, three parameters have been calculated: scavenging efficiency (through the concentration-weighted average (%ΔC)), the scavenging coefficient (λ) and the percentage of events with a decrease in pollen concentration (%ES) also called events with effective scavenging. 71% of rain events presented an effective scavenging that affected all types of pollen. The %ΔC mean value of total pollen was 24 ± 18% (positive values indicate an effective scavenging) and the types of pollen with the highest values were Castanea and Cupressaceae (71 and 40%, respectively). A linear model (R2 = 0.94) to estimate the pollen concentration after rain was built with variables such as pollen concentration before rain and other variables from a weather station and a disdrometer. Furthermore, we have shown the possibility of knowing in real time the probable Cupressaceae pollen concentration, from the initial pollen concentration and the physical parameters of rain (such as raindrop size, rain intensity or volume swept by raindrops in their falling path).

Effect of air temperature on forecasting the start of Cupressaceae pollen type in Ponferrada (Leon, Spain).

In order to survive periods of adverse cold climatic conditions, plant requirements are satisfied by means of physiological adaptations to prevent cells from freezing. Thus, the growth of woody plants in temperate regions slows down and they enter into a physiological state called dormancy. In order to identify the chilling and heat requirements to overcome the dormancy period of Cupressaceae pollen type in the south of Europe, we have carried out our study with aerobiological data from a 10-year (1996-2005) period in Ponferrada, León (Spain). For the chilling requirements the best result was with a threshold temperature of 7.1 degrees C and an average of 927 CH. Calculation of heat requirements was carried out with maximum temperature, with 490 growth degree days (GDD) needed, with a threshold temperature of 0 degrees C. We have used the 2002-2003, 2003-2004 and 2004-2005 periods in order to determine the real validity of the model. We have not used these years in developing the models. The dates predicted differ in only a few days from those observed: in 2002-2003 there was a difference of 11 days, in 2003-2004 predicted and observed dates were the same, but in 2004-2005 the difference obtained was of 43 days.

Allergenic proteins in Urtica dioica, a member of the Urticaceae allergenic family.

BACKGROUND: Allergy to the pollen of flowering plant species significantly affects the health of people in many parts of the world. Pollens of related genera usually share common antigens and are often, but not always, cross-reactive. Several studies have shown that Parietaria pollen is one of the most common causes of pollinosis in the Mediterranean area, whereas Urtica has no allergenic significance. OBJECTIVES: To report on the localization of Parietaria judaica major allergen in Urtica dioica pollen grains and on the detection of allergenic proteins in U. dioica pollen grains during the hydration-activation process. METHODS: A combination of transmission electron microscopy and immunocytochemical methods was used to locate allergenic proteins in U. dioica pollen grains after different periods of hydration-activation using the anti-Par j 1 (4.1.3.) monoclonal antibody and serum samples from allergic patients. RESULTS: No significant labeling was noted for Parj 1 allergen after 10, 15, and 20 minutes in the walls and cytoplasm. Slight labeling was observed for allergic proteins in the walls of U. dioica after 10 minutes of hydration, and no significant labeling was found after 15 and 20 minutes of hydration. CONCLUSIONS: Immunocytochemical methods confirmed the absence of cross-reactivity between 2 related genera, Parietaria and Urtica, and the lowest allergenic potential of U. dioica.

Prediction of airborne Alnus pollen concentration by using ARIMA models.

To take preventative measures to protect allergic people from the severity of the pollen season, one of aerobiology's objectives is to develop statistical models enabling the short- and long-term prediction of atmospheric pollen concentrations. During recent years some attempts have been made to apply Time Series analysis, frequently used in biomedical studies and atmospheric contamination to pollen series. The aim of this study is to understand the behaviour of atmospheric alder pollen concentrations in northwest Spain in order to develop predictive models of pollen concentrations by using Time Series analysis. The prediction line proposed for Oviedo and Ponferrada are similar (Arima 2,0,1) while in Vigo a more accurate model founded by Arima (3,0,1) and in Leon (1,0,1) was used. The results suggest that Ponferrada and Oviedo are the cities in northwest Spain where Alnus pollen allergic individuals should to take preventive measures to protect themselves from the severity of the pollen season. Alnus pollen values higher than 30 grains/m3, a quantity considered sufficient to trigger severe allergy symptoms of other trees of the Betulaceae family, could be reached during 25 days in some years. The predicted lines conformed with the observed values overall in the case of Leon and Ponferrada. Time Series regression models are especially suitable in allergology for evaluating short-term effects of time-varying pollen appearance in the atmosphere.

Urticaceae pollen concentration in the atmosphere of North Western Spain.

Plants of the Urticaceae family can develop into a pest on soils enriched with nitrogen. Urticaceae pollen is a biohazard because it elicits severe pollinosis. Pollen grains were sampled by using a Lanzoni seven-day-recording trap from February 1995-December 2000 in the atmosphere of the city of Ponferrada (Leon, North Western Spain). The Spearman test was used to analyse the statistical correlation between Urticaceae pollen and certain meteorological factors in different main pollination periods. Maximum values are reached in June and July, minimum levels are recorded in January and December. The parameters bearing the greatest positive influence on the occurrence of Urticaceae pollen grains are: temperature (maximum, minimum and mean), humidity (absolute, wet-bulb temperature, dew point and mixing ratio) and south western wind direction; negative parameters are: relative humidity, rainfall and period without wind. The highest correlation coefficients were obtained with temperature and wet-bulb. Absolute humidity and wet-bulb temperature yielded better correlation than relative humidity; hence, these two parameters must be included in this type of study. The use of one main pollination period or another in statistical analysis has an influence on the coefficient value. The behaviour of the pollen grains in the atmosphere during the year also influences the results.