Extension of WRF-Chem for birch pollen modelling-a case study for Poland.

In recent years, allergies due to airborne pollen allergens have shown an increasing trend, along with the severity of allergic symptoms in most industrialized countries, while synergism with other common atmospheric pollutants has also been identified as affecting the overall quality of citizenly life. In this study, we propose the state-of-the-art WRF-Chem model, which is a complex Eulerian meteorological model integrated on-line with atmospheric chemistry. We used a combination of the WRF-Chem extended towards birch pollen, and the emission module based on heating degree days, which has not been tested before. The simulations were run for the moderate season in terms of birch pollen concentrations (year 2015) and high season (year 2016) over Central Europe, which were validated against 11 observational stations located in Poland. The results show that there is a big difference in the model's performance for the two modelled years. In general, the model overestimates birch pollen concentrations for the moderate season and highly underestimates birch pollen concentrations for the year 2016. The model was able to predict birch pollen concentrations for first allergy symptoms (above 20 pollen m-3) as well as for severe symptoms (above 90 pollen m-3) with probability of detection at 0.78 and 0.68 and success ratio at 0.75 and 0.57, respectively for the year 2015. However, the model failed to reproduce these parameters for the year 2016. The results indicate the potential role of correcting the total seasonal pollen emission in improving the model's performance, especially for specific years in terms of pollen productivity. The application of chemical transport models such as WRF-Chem for pollen modelling provides a great opportunity for simultaneous simulations of chemical air pollution and allergic pollen with one goal, which is a step forward for studying and understanding the co-exposure of these particles in the air.

Prevalence of allergic rhinitis and asthma in Poland in relation to pollen counts.

INTRODUCTION: Despite the known role of pollen allergens in causing allergy symptoms in sensitized individuals, there are few publications investigating the relationship between pollen exposure in different regions and the prevalence of inhalant allergy. AIM: To assess the association between the prevalence of allergic rhinitis and asthma and the degree of exposure to pollen in various regions of Poland. MATERIAL AND METHODS: Completed questionnaires of 9,443 subjects living in four urban centres (Wroclaw, Katowice, Warsaw, Bialystok), collected within part of the ECAP project, were analyzed. Children aged 6-7 (n = 2,278), adolescents aged 13-14 (n = 2,418), and adults aged 20-44 (n = 4,747) constituted 24.2%, 25.6% and 50.3% of the respondents, respectively. The clinical part (including skin prick tests, an assay of Timothy grass-specific IgE), was attended by 24% of the respondents. Data from 6-year pollen monitoring served to characterize birch and grass pollen seasons. RESULTS: We found insignificant negative associations between the duration of birch pollen season and the prevalence of declared allergic rhinitis and asthma during the season across all age groups. There were insignificant inverse associations between the number of days with above-threshold and high grass pollen concentrations, total grass pollen count and the prevalence of declared allergic rhinitis and asthma during the season across all age groups. Associations noted in the clinical part were also non-significant; however, these trends were not uniform across the age groups. CONCLUSIONS: Our findings do not confirm the hypothesis of a positive association between pollen exposure and the prevalence of allergic rhinitis and asthma.

The impact of meteorological conditions on the concentration of alder pollen in Sosnowiec (Poland) in the years 1997-2017.

The aim of the work was to compare the alder pollen seasons in the years 1997-2017 in Sosnowiec. The measurements of pollen concentration were taken with the volumetric method using Burkard's apparatus. The impact of atmospheric conditions on the daily alder pollen grain concentration, the annual totals, and the duration of pollen seasons were studied. The dependency between each meteorological condition and different features of the alder pollen season was determined by using Pearson's correlation coefficients, variance analysis with multiple comparison tests, and the linear regression model using backward elimination. It was proven that the temperatures directly preceding the pollination, i.e. the January and February temperatures as well as those from the period from 210 to 180 days preceding the beginning of the season, have the greatest impact on the beginning of the alder pollen season. The value of the daily alder pollen concentration in Sosnowiec showed a positive statistically significant correlation with the air temperature and sunshine duration and a negative correlation with the thickness of the snow cover and air relative humidity. The daily concentration also depended on the type of the weather front, direction of air mass inflow, and the type of the inflowing air mass. The season temperatures and the thermal conditions which were present in the summer of the preceding year impacted the annual totals (SPI) of the alder pollen grains.

Forecasting model of Corylus, Alnus, and Betula pollen concentration levels using spatiotemporal correlation properties of pollen count.

The aim of the study was to create and evaluate models for predicting high levels of daily pollen concentration of Corylus, Alnus, and Betula using a spatiotemporal correlation of pollen count. For each taxon, a high pollen count level was established according to the first allergy symptoms during exposure. The dataset was divided into a training set and a test set, using a stratified random split. For each taxon and city, the model was built using a random forest method. Corylus models performed poorly. However, the study revealed the possibility of predicting with substantial accuracy the occurrence of days with high pollen concentrations of Alnus and Betula using past pollen count data from monitoring sites. These results can be used for building (1) simpler models, which require data only from aerobiological monitoring sites, and (2) combined meteorological and aerobiological models for predicting high levels of pollen concentration.

The impact of data assimilation into the meteorological WRF model on birch pollen modelling.

We analyse the impact of ground-based data assimilation to the Weather Research and Forecasting (WRF) meteorological model on parameters relevant for birch pollen emission calculations. Then, we use two different emission databases (BASE - no data assimilation, OBSNUD - data assimilation for the meteorological model) in the chemical transport model and evaluate birch pollen concentrations. Finally, we apply a scaling factor for the emissions (BASE and OBSNUD), based on the ratio between simulated and observed seasonal pollen integral (SPIn) to analyse its impact on birch concentrations over Central Europe. Assimilation of observational data significantly reduces model overestimation of air temperature, which is the main parameter responsible for the start of pollen emission and amount of released pollen. The results also show that a relatively small bias in air temperature from the model can lead to significant differences in heating degree days (HDD) value. This may cause the HDD threshold to be attained several days earlier/later than indicated from observational data which has further impact on the start of pollen emission. Even though the bias for air temperature was reduced for OBSNUD, the model indicates a start for the birch pollen season that is too early compared to observations. The start date of the season was improved at two of the 11 stations in Poland. Data assimilation does not have a significant impact on the season's end or SPIn value. The application of the SPIn factor for the emissions results in a much closer birch pollen concentration level to observations even though the factor does not improve the start or end of the pollen season. The post-processing of modelled meteorological fields, such as the application of bias correction, can be considered as a way to further improve the pollen emission modelling.

Bioaerosols on the atmospheric super highway: An example of long distance transport of Alternaria spores from the Pannonian Plain to Poland.

Alternaria spores are pathogenic to agricultural crops, and the longest and the most severe sporulation seasons are predominantly recorded in rural areas, e.g. the Pannonian Plain (PP) in South-Central Europe. In Poland (Central Europe), airborne Alternaria spore concentrations peak between July and August. In this study, we test the hypothesis that the PP is the source of Alternaria spores recorded in Poland after the main sporulation season (September-October). Airborne Alternaria spores (2005-2019) were collected using volumetric Hirst spore traps located in 38 locations along the potential pathways of air masses, i.e. from Serbia, Romania and Hungary, through the Czech Republic, Slovakia and Ukraine, to Northern Poland. Three potential episodes of Long Distance Transport (LDT) were selected and characterized in detail, including the analysis of Alternaria spore data, back trajectory analysis, dispersal modelling, and description of local weather and mesoscale synoptic conditions. During selected episodes, increases in Alternaria spore concentrations in Poznan were recorded at unusual times that deviated from the typical diurnal pattern, i.e. at night or during morning hours. Alternaria spore concentrations on the PP were very high (>1000 spores/m3) at that time. The presence of non-local Ambrosia pollen, common to the PP, were also observed in the air. Air mass trajectory analysis and dispersal modelling showed that the northwest part of the PP, north of the Transdanubian Mountains, was the potential source area of Alternaria spores. Our results show that Alternaria spores are transported over long distances from the PP to Poland. These spores may markedly increase local exposure to Alternaria spores in the receptor area and pose a risk to both human and plant health. Alternaria spores followed the same atmospheric route as previously described LDT ragweed pollen, revealing the existence of an atmospheric super highway that transports bioaerosols from the south to the north of Europe.

High Ambrosia pollen concentrations in Poland respecting the long distance transport (LDT).

High Ambrosia pollen concentrations in Poland rather rarely come from the local sources. The aim of this study was to define the temporal and spatial differences of the high Ambrosia pollen concentrations by creating models for the pollen transport from the distant sources. This study was thought to determine the direction of the air masses inflow into Poland, carrying Ambrosia pollen, from areas of the bordering countries with the pollen concentrations higher than iSTOTEN_n Poland. Pollen and meteorological datasets at 8 monitoring sites in Poland, and daily pollen concentrations at 11 sites in the Czech Republic, 5 sites in Slovakia and 3 sites in Ukraine were analysed recently. Days with concentrations ≥10 Pollen/m3 and concurrent meteorological situations were analysed in great deal. The HYSPLIT model was applied to compute backward trajectories up to 4 days backward (96 h) and at three altitudes: 20, 500 and 1000 m above ground level (a.g.l.). High pollen concentrations occur most frequently when the air masses inflow into Poland from southerly (S, SE, SW, 44%) and easterly (E, 6%) directions and in no advection situations (25%). In years with the highest frequency of days over 10 Pollen/m3, the prevailing directions of the pollen influx into Poland were from the South (2004-2006, 2008, 2011) but in one year (2014) from the East. Trajectories for the studied period show that air masses come most frequently from Slovakia and the Czech Republic. Sometimes, the Ambrosia pollen transport happens from Ukraine.

A study on the spatial and temporal variability in airborne Betula pollen concentration in five cities in Poland using multivariate analyses.

During the spring period, Betula pollen is the main cause of inhalant allergies in Poland and therefore it is important to monitor and forecast airborne pollen concentrations of this taxon. This study conducted a comparative analysis of the basic characteristics of Betula pollen seasons at the regional scale. The study was carried out from 2001 to 2016 in five cities in Poland: Lublin, Warsaw, Cracow, Sosnowiec, and Szczecin. To find the attributes of birch pollen seasons that mostly differentiated the individual cities, a general discriminant analysis (GDA) was performed, while a principal component analysis (PCA) allowed us to reduce the data space and present a scatterplot of PCA scores in order to compare pollen seasons in the individual cities. The contingency table was also analyzed to check whether there was a significant relationship between pollen counts in the studied years and cities. At most of the sites, biennial cycles of low and high pollen concentrations can be observed. Due to the high variation in seasons in each of these cities, two data groups were distinguished: Group 1 was composed of seasons with high pollen deposition (2001, 2003, 2006, 2008, 2010, 2012, 2014, 2016), and Group 2 comprising the other seasons. Multivariate analyses were performed on both these groups as well as in the entire dataset. End98, Peak Value, and Annual Total had the highest discriminant power. In Group 1, Warsaw and Sosnowiec differed the most in the investigated parameters, while Cracow and Szczecin differed the least. In both groups, most seasons with the highest pollen birch concentration were observed in Lublin, followed by Warsaw, while in Cracow, the number of such seasons was the smallest.