Assessment of neural networks and time series analysis to forecast airborne Parietaria pollen presence in the Atlantic coastal regions.

Pollen forecasting models are a useful tool with which to predict episodes of type I allergenic risk and other environmental or biological processes. Parietaria is a wind-pollinated perennial herb that is responsible for many cases of severe pollinosis due to its high pollen production, the long persistence of the pollen grains in the atmosphere and the abundant presence of allergens in their cytoplasm and walls. The aim of this paper is to develop artificial neural networks (ANNs) to predict airborne Parietaria pollen concentrations in the northwestern part of Spain using a 19-year data set (1999-2017). The results show a significant increase in the length of time Parietaria pollen is in the air, as well as significant increases in the annual Parietaria pollen integral and mean daily maximum pollen value in the year. The Neural models show the ability to forecast airborne Parietaria pollen concentrations 1, 2, and 3 days ahead. A developed model with five input variables used to predict concentrations of airborne Parietaria pollen 1 day ahead shows determination coefficients between 0.618 and 0.652.

Fraxinus pollen and allergen concentrations in Ourense (South-western Europe).

In temperate zones of North-Central Europe the sensitization to ash pollen is a recognized problem, also extended to the Northern areas of the Mediterranean basin. Some observations in Switzerland suggest that ash pollen season could be as important as birch pollen period. The allergenic significance of this pollen has been poorly studied in Southern Europe as the amounts of ash pollen are low. Due to the high degree of family relationship with the olive pollen major allergen (backed by a sequence identity of 88%), the Fraxinus pollen could be a significant cause of early respiratory allergy in sensitized people to olive pollen as consequence of cross-reactivity processes. Ash tree flowers in the Northwestern Spain during the winter months. The atmospheric presence of Ole e 1-like proteins (which could be related with the Fra a 1 presence) can be accurately detected using Ole e 1 antibodies. The correlation analysis showed high Spearman correlation coefficients between pollen content and rainfall (R(2)=-0.333, p<0.01) or allergen concentration and maximum temperature (R(2)=-0.271, p<0.01). In addiction CCA analysis showed not significant differences (p<0.05) between the component 1 and 2 variables. PCFA analysis plots showed that the allergen concentrations are related to the presence of the Fraxinus pollen in the air, facilitating the wind speed its submicronic allergen proteins dispersion. In order to forecast the Fraxinus allergy risk periods, two regression equations were developed with Adjusted R(2) values around 0.48-0.49. The t-test for dependent samples shows no significant differences between the observed data and the estimated by the equations. The combination of the airborne pollen content and the allergen quantification must be assessed in the epidemiologic study of allergic respiratory diseases.

Airborne pollen trends in the Iberian Peninsula.

Airborne pollen monitoring is an effective tool for studying the reproductive phenology of anemophilous plants, an important bioindicator of plant behavior. Recent decades have revealed a trend towards rising airborne pollen concentrations in Europe, attributing these trends to an increase in anthropogenic CO2 emissions and temperature. However, the lack of water availability in southern Europe may prompt a trend towards lower flowering intensity, especially in herbaceous plants. Here we show variations in flowering intensity by analyzing the Annual Pollen Index (API) of 12 anemophilous taxa across 12 locations in the Iberian Peninsula, over the last two decades, and detecting the influence of the North Atlantic Oscillation (NAO). Results revealed differences in the distribution and flowering intensity of anemophilous species. A negative correlation was observed between airborne pollen concentrations and winter averages of the NAO index. This study confirms that changes in rainfall in the Mediterranean region, attributed to climate change, have an important impact on the phenology of plants.

Oleaceae cross-reactions as potential pollinosis cause in urban areas.

It is worth noting the allergological problems induced by a not accurate design of the ornamental vegetation in the parks and streets of the cities. Usually, in the Oleaceae family, only the olive pollen is considered an important aeroallergen but other species of the family could be an important source of airborne pollen allergens. Pollen from Fraxinus, Olea and Ligustrum and its main aeroallergens were sampled in the atmosphere of an urban area in North-Western Spain during 2011. The allergen bioaerosol content was quantified by using specific 2-site ELISA and Ole e 1 antibodies. The Fra e 1 and Lig v 1 allergens were detected by means Ole e 1 antibodies. This fact demonstrates the cross-reactivity between the main allergens of Fraxinus, Olea and Ligustrum, plants widely species used as ornamental in the cities. Therefore, the urban allergenic people sensitized to Olea pollen could present allergenic reactions during the winter (due to ash pollen allergens), the spring (caused by olive pollen allergens) and the early summer (triggered by the privet flowering). As a consequence, sensitivity to the pollen of one species may favour development of sensitivity to all three species as consequence of the priming effect. The combination of pollen count and the allergen quantification must be assessed in the epidemiologic study of allergic respiratory diseases.

Assessment of Quercus flowering trends in NW Spain.

This paper sought to chart airborne Quercus pollen counts over the last 20 years in the region of Galicia (NW Spain) with a view to detecting the possible influence of climate change on the Quercus airborne pollen season (APS). Pollen data from Ourense, Santiago de Compostela, Vigo and Lugo were used. The Quercus airborne pollen season was characterized in terms of the following parameters: pollen season start and end dates, peak pollen count, pollen season length and pollen index. Several methods, dates and threshold temperatures for determining the chill and heat requirements needed to trigger flowering were applied. A diverse APS onset timing sequence was observed for the four cities as Quercus flowers few days in advance in Vigo. The variations observed could be related to differences in the meteorological conditions or the thermal requirements needed for flowering. Thermal requirements differed depending on local climate conditions in the study cities: the lowest values for chilling accumulation were recorded in Vigo and the highest in Lugo, whereas the lowest heat accumulation was achieved in Vigo. Differences in APS trends between cities may reflect variations in weather-related trends. A significant trend towards rising Quercus pollen indices and higher maximum daily mean pollen counts was observed in Ourense, linked to the more marked temperature increase across southern Galicia. A non-uniform trend towards increased temperatures was noted over the study period, particularly in late summer and early autumn in all four study cities. Additionally, an increase in spring temperatures was observed in south-western Galicia.

Pollen Raman spectra database: application to the identification of airborne pollen.

Raman microspectroscopy allows a non-destructive identification of airborne particles. However, the identification of particles such as pollen is hindered by the absence of a spectral library. Although reference spectra of pollen have been published before, they have always been limited to a certain number of species. In this work, Raman spectra of 34 pollen types are presented and were used to build a pollen spectra primary library. Afterward, the applicability of this database for detecting and identifying pollen in airborne samples was tested. Airborne pollen samples collected during April, May and August were compared with blank pollen spectra by means of Hit Quality Index. Although a much larger library would be required, our results showed that all first hits correspond to the same blank pollen species of the questioned sample from the air. This possibility is an innovative idea and a promising line of investigation for future RAMAN technology development in the area of aerobiology.

Influence of pollen level on hospitalizations for asthma.

The effect of pollen level on asthma hospitalizations is still under debate. The aim of this study was to analyze hospital admissions due to asthma and its relation with environmental pollen and meteorological factors. During 13 years, we included every patient admitted with asthma as primary or secondary diagnosis. For this purpose, we used a case-crossover analysis to compare pollen concentrations at the time of admission with values of the same variables 2 to 6 days before admission. We included 6,687 hospital admissions. High maximum temperature and low humidity were associated with lower risk of asthma admissions. High mean pollen levels exerted a moderate effect and high maximum pollen levels led to a dramatic increase of hospital admissions due to asthma, especially among females. In conclusion, environmental pollen level increases the risk of asthma hospital admissions.

Evaluation of atmospheric Poaceae pollen concentration using a neural network applied to a coastal Atlantic climate region.

In the South of Europe an important percentage of population suffers pollen allergies, being the Poaceae pollen the major source. One of aerobiology's objectives is to develop statistical models enabling the short- and long-term prediction of atmospheric pollen concentrations to take preventative measures to protect allergic patients from the severity of the atmospheric pollen season. The implementation of a computational model based on supervised MLP neural network was applied for the prediction of the atmospheric Poaceae pollen concentration. There is a good correlation between the values predicted by the ANN for the training cases in comparison with the real pollen concentrations. A high coefficient of linear regression (R(2)) of 0.9696 was obtained. The accuracy of the neural network developed was tested with data from 2006 and 2007, which was not taken into account to establish the aforementioned models. Neural networks provided us a good tool to forecasting allergenic airborne pollen concentration helping the automation of the prediction system in the aerobiological information diffusion to the population suffering from allergic problems.

Poaceae pollen in Galicia (N.W. Spain): characterisation and recent trends in atmospheric pollen season.

Airborne Poaceae pollen counts are greatly influenced by weather-related parameters, but may also be governed by other factors. Poaceae pollen is responsible for most allergic reactions in the pollen-sensitive population of Galicia (Spain), and it is therefore essential to determine the risk posed by airborne pollen counts. The global climate change recorded over recent years may prompt changes in the atmospheric pollen season (APS). This survey used airborne Poaceae pollen data recorded for four Galician cities since 1993, in order to characterise the APS and note any trends in its onset, length and severity. Pollen sampling was performed using Hirst-type volumetric traps; data were subjected to Spearman's correlation test and regression models, in order to detect possible correlations between different parameters and trends. The APS was calculated using ten different methods, in order to assess the influence of each on survey results. Finally, trends detected for the major weather-related parameters influencing pollen counts over the study period were compared with those recorded over the last 30 years. All four cities displayed a trend towards lower annual total Poaceae pollen counts, lower peak values and a smaller number of days on which counts exceeded 30, 50 and 100 pollen grains/m(3). Moreover, the survey noted a trend towards delayed onset and shorter duration of the APS, although differences were observed depending on the criteria used to define the first and the last day of the APS.

Artificial neural networks as a useful tool to predict the risk level of Betula pollen in the air.

An increasing percentage of the European population suffers from allergies to pollen. The study of the evolution of air pollen concentration supplies prior knowledge of the levels of pollen in the air, which can be useful for the prevention and treatment of allergic symptoms, and the management of medical resources. The symptoms of Betula pollinosis can be associated with certain levels of pollen in the air. The aim of this study was to predict the risk of the concentration of pollen exceeding a given level, using previous pollen and meteorological information, by applying neural network techniques. Neural networks are a widespread statistical tool useful for the study of problems associated with complex or poorly understood phenomena. The binary response variable associated with each level requires a careful selection of the neural network and the error function associated with the learning algorithm used during the training phase. The performance of the neural network with the validation set showed that the risk of the pollen level exceeding a certain threshold can be successfully forecasted using artificial neural networks. This prediction tool may be implemented to create an automatic system that forecasts the risk of suffering allergic symptoms.

Incidence of pollinosis in the city of A Coruña: correlation with aerobiological data.

An atmospheric pollen count was carried out in the city of A Coruña during 1999 using two pollen traps located at two different points in the city. A total number of 6979 and 3536 pollen grains, respectively, were identified, the majority during the Spring and Summer. Further, patients living near the pollen traps were selected from among those diagnosed as suffering from respiratory allergies by the Allergy Department of A Coruña's Juan Canalejo Hospital. The patients had at least one positive skin test for some pollen type, had not received immunotherapy in the last year, and were willing to fill in a symptoms booklet during the study period. The results obtained reveal the pollen types that produce the greatest number of skin sensitization cases (Poaceae, Plantago, Chenopodium and Parietaria), with a positive correlation between the atmospheric pollen concentration of such taxa and the frequency of allergy symptoms. This has enabled the setting of pollen values, above which A Coruña's inhabitants are considered to be at risk.

Phenological behaviour of Quercus in Ourense (NW Spain) and its relationship with the atmospheric pollen season.

Knowing the beginning of the pollen season is of particular importance to people allergic to a given pollen. Phenological studies in combination with aerobiological studies enable us to observe the relationship between the reproductive phenology of the species and their airborne pollen curves. They also enable us to study the relationship between the release of pollen from anthers and its presence in the atmosphere. The objectives of this study are (1) to determine chill and heat requirements for different phenological phases in the Quercus species present in Ourense (Spain), (2) to verify the synchronization between the flowering event and the presence of Quercus pollen in the air, (3) to select the best criterion for determining the onset of the pollen season according to phenological data, and finally, (4) to obtain models enabling us to determine the onset of the pollen season. Pollen monitoring was carried out from 1993 to 2001, by means of a 7-day Lanzoni VPPS pollen trap and, in order to characterize the floral phenophase of different Quercus species, a sampling method was applied from February to June 2001. We observed that climatic and biotic factors can produce a delay in the onset of the pollen season. Temperatures above 8 degrees C and between 6 degrees C to 8 degrees C are good threshold temperatures for estimating chill and heat requirements respectively. Medium-distance transportation of Quercus robur and Quercus pyrenaica pollen from areas 10-30 km away influences the concentrations of Quercus pollen registered in Ourense.

Parietaria pollinosis in an Atlantic area: clinical and palynological data.

BACKGROUND: Parietaria pollen is considered as one of the most common causes of allergic respiratory symptoms in the Mediterranean area but its presence is limited in the Atlantic area. Some leading patients from Muros, a small town on the Spanish Atlantic coast, complaining of nearly all year round respiratory symptoms happened to be allergic to Parietaria pollen. AIM OF THE STUDY: To evaluate the prevalence of Parietaria sensitization among patients from this Atlantic town, and its correlation with aerobiological data (concentration of Urticaceae pollen). PATIENTS AND METHODS: Eighty-nine patients suffering from rhinoconjunctivitis and/or asthma from the area of Muros between January 1998 and January 1999 were included. Skin prick tests and serum-specific IgE (CAP Pharmacia) to Parietaria judaica and a battery of perennial or seasonal allergens were performed. Information about the seasonal and hourly rhythm of symptoms was obtained in each patient sensitized to Parietaria pollen. Atmospheric pollen was collected, using a Hirst-type volumetric pollen sampler, during 1998. RESULTS: Parietaria allergy was detected in 22 patients (25%) and represented the second most important aeroallergen after mites and along with grass pollen. The total atmospheric pollen recorded in Muros during the study period was 27,515 pollen grains, Urticaceae being the most important one (18,554 grains, 67% of the total). The proportion of Urticaceae pollen found in Muros was the highest among all samplers belonging to the Spanish Aerobiology Network. Maximum values of Urticaceae pollen were recorded during May and June. Intradiurnal variation of pollen counts showed maximum values between 11 a.m. and 1 p.m. A parallelism was observed between the rate of symptomatic patients and Parietaria type grain pollen count. CONCLUSION: The prevalence of Parietaria pollen sensitization seems to be very important in this Atlantic area. The presence of very high levels of this pollen in its atmosphere explains this fact. Such sensitization should be taken into account concerning specific diagnostic tests.