Identifying key environmental factors to model Alt a 1 airborne allergen presence and variation.

Fungal spores, commonly found in the atmosphere, can trigger important respiratory disorders. The glycoprotein Alt a 1 is the major allergen present in conidia of the genus Alternaria and has a high clinical relevance for people sensitized to fungi. Exposure to this allergen has been traditionally assessed by aerobiological spore counts, although this does not always offer an accurate estimate of airborne allergen load. This study aims to pinpoint the key factors that explain the presence and variation of Alt a 1 concentration in the atmosphere in order to establish exposure risk periods and improve forecasting models. Alternaria spores were sampled using a Hirst-type volumetric sampler over a five-year period. The allergenic fraction from the bioaerosol was collected using a low-volume cyclone sampler and Alt a 1 quantified by Enzyme-Linked ImmunoSorbent Assay. A cluster analysis was executed in order to group days with similar environmental features and then analyze days with the presence of the allergen in each of them. Subsequently, a quadratic discriminant analysis was performed to evaluate if the selected variables can predict days with high Alt a 1 load. The results indicate that higher temperatures and absolute humidity favor the presence of Alt a 1 in the atmosphere, while time of precipitation is related to days without allergen. Moreover, using the selected parameters, the quadratic discriminant analysis to predict days with allergen showed an accuracy rate between 67 % and 85 %. The mismatch between daily airborne concentration of Alternaria spores and allergen load can be explained by the greater contribution of medium-to-long distance transport of the allergen from the major emission sources as compared with spores. Results highlight the importance of conducting aeroallergen quantification studies together with spore counts to improve the forecasting models of allergy risk, especially for fungal spores.

Effect of prevailing winds and land use on Alternaria airborne spore load.

Alternaria spores are a common component of the bioaerosol. Many Alternaria species are plant pathogens, and their conidia are catalogued as important aeroallergens. Several aerobiological studies showing a strong relationship between concentrations of airborne spore and meteorological parameters have consequently been developed. However, the Alternaria airborne load variation has not been thoroughly investigated because it is difficult to assess their sources, as they are a very common and widely established phytopathogen. The objective of this study is to estimate the impact of vegetation and land uses as potential sources on airborne spore load and to know their influence, particularly, in cases of long-medium distance transport. The daily airborne spore concentration was studied over a 5-year period in León and Valladolid, two localities of Castilla y León (Spain), with differences in their bioclimatic and land use aspects. Moreover, the land use analysis carried out within a 30 km radius of each monitoring station was combined with air mass data in order to search for potential emission sources. The results showed a great spatial variation between the two areas, which are relatively close to each other. The fact that the spore concentrations recorded in Valladolid were higher than those in León was owing to prevailing winds originating from large areas covered by cereal crops, especially during the harvest period. However, the prevailing winds in León came from areas dominated by forest and shrubland, which explains the low airborne spore load, since the main Alternaria sources were the grasslands located next to the trap. Furthermore, the risk days in this location presented an unusual wind direction. This study reveals the importance of land cover and wind speed and direction data for establishing potential airborne routes of spore transport in order to improve the Alternaria forecasting models. The importance of conducting Alternaria aerobiological studies at a local level is also highlighted.

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).

Distribuição de esporos de Cladosporium sppno ar atmosférico de Caxias do Sul, RS, Brasil,durante dois anos de estudo / Cladosporium spp spores distribution in the atmospheric air of Caxias do Sul-RS, Brazil, during a two-year study

Os esporos de fungos estão distribuídos em grande quantidade naatmosfera e, alguns deles, apresentam capacidade de causar doençasem seres humanos, animais e vegetais. Dentre os variados táxons destaca-se Cladosporium spp, um dos fungos mais cosmopolitas e de maiorconcentração no ar. Esporos de Cladosporium spp têm sido caracterizadoscomo importantes alérgenos.Objetivos: Medir as concentrações de esporos de Cladosporium sppna atmosfera de Caxias do Sul, RS, Brasil, durante os anos de 2001 e2002 e avaliar a relação destas, com parâmetros meteorológicos.Métodos: Amostras diárias foram coletadas, utilizando um aparelhotipo Hirst (Burkard®).Resultados: Os resultados mostraram que Cladosporium spp tempresença constante no ar. Em 2001 foram contabilizados 133.586 esporos/m3, com valor máximo diário de 3.265 esporos/m3 e mensal de24.912 esporos/m3, no mês de março. Em 2002 o número total foi de118.766 esporos/m3 com máximo diário de 4.470 esporos/m3 e mensalde 29.816 esporos/m3, em janeiro. A análise com os parâmetrosmeteorológicos mostrou correlação positiva com temperatura média enegativa com a umidade. Os períodos de maior concentração ocorreramcom temperaturas médias mais elevadas, no entanto, a umidade altatem um efeito negativo na distribuição destes esporos por favorecer ahidratação dos mesmos, que sedimentam ao solo.Conclusão: Os dados obtidos podem ser úteis nas áreas da patologiahumana, especialmente nos processos alérgicos, na patologia animal evegetal, em trabalhos com finalidades de preservação de acervo cultural,no controle de infecções e na ecologia.

Fungal spores are distributed in large amounts in the outdoor air, andsome of them may cause diseases in human beings, animals, and plants.Among several taxa, Cladosporium spp is one of the most ubiquitous andmost widely distributed, being found in high concentrations in the air.Cladosporium spp spores have been classified as important allergens,and are, therefore, important to the study of allergies.Objectives: To measure the concentrations of Cladosporium sppspores in the outdoor air of Caxias do Sul, Southern Brazil, during 2001and 2002, and to evaluate the association of these concentrations withmeteorological parameters.Methods: Daily samples were collected using a Hirst sampler(Burkard®).Results: The results showed that Cladosporium spp spores are oftenpart of the air. In 2001, the total amount was 133,586 spores/m3; withmaximum daily and monthly concentration of 3,265 spores/m3, and24,912 spores/m3 in March, respectively. In 2002, the total amount was118,766 spores/m3; with maximum daily and monthly concentration of4,470 spores/m3 and 29,816 spores/m3 in January. The meteorologicalparameters showed a positive correlation with the temperature averageand a negative one regarding humidity. The highest levels were found athigher temperature averages, however, elevated humidity has a negativeeffect on the distribution of these spores, contributing to their hydrationand deposition on the soil.Conclusions: The data obtained can be useful in human pathologyarea - especially in allergy - animal and plants pathology, in studies ofcultural inventory preservation, infection control and ecology.

Variações anuais do conteúdo polínico de mimosa scabrella na atmosfera de Caxias do Sul, Brasil / Annual variation of the pollinic content of Mimosa scabrella in the atmosphere ofCaxias do Sul, Brazil

A família Mimosaceae está representada no município de Caxias do Sul por 10 gêneros e 37 espécies. O tipo polínico de maior representatividade na atmosfera é Mimosa scabrella, árvore de porte médio, muito indicada para reflorestamento. O monitoramento polínico atmosférico vem sendo realizado desde o ano de 2001, utilizando-se o captador volumétrico de sucção do tipo Hirst, modelo Burkard®, instalado no topo do Hospital Geral. A concentração total do tipo polínico Mimosa scabrella durante os anos de 2001 a 2006 foi 17.804 grãos de pólen, o que o situa em segundo lugar no espectro polínico da cidade. Em 2001, foram registrados 3.656 grãos de pólen, 2.087 grãos em 2002 e 4.379 em 2003, 1.928 em 2004, 1.524 em 2005 e 4.230 em 2006. Os picos mensais ocorreram no mês de agosto, com exceção do ano de 2003 que foi em setembro. Por sua elevada concentração, seria conveniente que estudos epidemiológicos futuros testassem extratos com antígenos desse pólen.

The Mimosaceae family is represented in the city of Caxias do Sul by ten genera and 37 species. The most representative pollinic type in the atmosphere is Mimosa scabrella, an average sized tree, between 10 and 12 m high, well suited for reforestation managing. The monitoring of atmosphere pollen is been held since the year of 2001 using a Hirst volumetric spore trap sampler, Burkard® model, placed on the roof of the citie´s General Hospital. The total pollen concentration of Mimosa scabrella from the year of 2001 to 2006 was 17,804 pollen grains/m³, which makes it the second most common in the city pollen specter. In 2001, 3,656 pollen grains/m³ were recorded, 2,087 in 2002, 4,379 in 2003, 1,928 in 2004, 1,524 in 2005, 4,230 in 2006. The monthly peaks occurred in August, except in the year of 2003 (September, in that case). For its high concentration, it should be convenient to future epidemiologic studies to test antigens extract of such pollinic type.

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.

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.

Bioclimatic indices as a tool in pollen forecasting.

The use of bioclimatic indices could be a major step forward in the methodology of pollen forecasting. The basis for this proposal is that simple meteorological parameters do not reflect the global status of the atmosphere, but merely some static measurements. However, pollen dispersal is, above all, a dynamic phenomenon, and this fact should be reflected in the variables we used to explain it. Here, we test the two methodologies for routine pollen forecasting by comparing correlation coefficients using the same daily Poaceae airborne pollen data base from León (6 years, from 1994 to 1999) as the dependent variable and either simple daily meteorological variables or compound daily bioclimatic indices as independent variables. Both simple and compound indices reproduced the same profile of evolution of plant eco-physiological requirements, as the length of the study period during the pollen season increased. However, for time frames larger than the main pollen period, bioclimatic indices gave superior coefficients, which seems to indicate that these could be more valuable for pre-season pollen forecasting. The continentality index produced the highest mean coefficient, higher than those generated by any meteorological variable. Furthermore, at least for a Mediterranean climate, site location and evapotranspiration in relation to precipitation seem to be the most promising factors for increasing success when forecasting Poaceae airborne pollen concentration.