Allergic rhinitis affects half a billion people globally, including a fifth of the Australian population. In Canberra, the nation’s capital, more than 1 in 3 people suffer from the disease and this can cause significant negative impacts on community wellbeing as well as the local economy. Thunderstorm Asthma events have also been recorded and have led to increasing public and government concern with regard to improving our responses to thunderstorm asthma and other environmental drivers of respiratory morbidity and mortality. Over the last decade the Canberra Pollen Monitoring Program has been monitoring airborne allergenic pollen and fungal spores in Canberra on a daily basis. These records of airborne pollen are beginning to provide a historical lens to create pollen taxa calendars, estimate the pollen season length and variability, and to provide the basis for forecast evaluation.

In this presentation we provide the latest information on the seasonal nature of the most significant airborne tree pollen, herb pollen and spore types for Canberra, Australia. The development of a citizen science approach designed to provide the public with daily airborne allergenic pollen information while allowing users to give feedback on their hay fever symptoms, is also providing insights into the impact of airborne pollen on people in the region. We also consider why Canberra is a hotspot for allergic rhinitis in Australia and discuss how pollen and spore exposure is likely to be altered by future climate change and rapid urban development.

How to cite: Haberle, S. and Keaney, B.: A decade of airborne pollen monitoring in an allergic rhinitis hotspot of Australia: insights into how climate change and urban development are altering pollen seasons and human wellbeing., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3390, https://doi.org/10.5194/egusphere-egu25-3390, 2025.

Airborne pollen significantly impacts air quality, human health, and ecosystems. Monitoring pollen trends is critical for understanding these effects, especially as pollen allergies affect millions of persons globally, reducing respiratory health and life quality. Pollen data provide relevant information about the impacts of climate change on vegetation, with shifts in flowering timing serving as indicators of ecological responses. These trends are also vital for forecasting agricultural yields, particularly in Mediterranean climates where water availability and temperature are increasingly erratic.

This study examines flowering timing and intensity trends for 12 anemophilous taxa across 12 locations in the Iberian Peninsula from 1994 to 2023. Using data from Hirst pollen monitoring method, we calculated annual trends in several flowering date indicators (e.g. peak pollen day, start of flowering, duration of pollen season) and other indicators for pollen production (e.g. peak daily pollen concentration or seasonal pollen integral). Statistical analyses assessed linear trends, comparing variations among woody and herbaceous taxa, as well as regional differences between Mediterranean and more temperate areas.

The date of maximum flowering advanced by an average of -0.054 days/year, with species-specific variations ranging from -4.2 (Amaranthaceae) to +7.3 days/year (Fraxinus). Woody taxa, especially those flowering in winter or early spring, exhibited varied responses. For instance, in some locations, Cupressus showed a slight delay with an average of -0.16 days/year, while Betula displayed a more marked delay, averaging -0.33 days/year. These delays are likely linked to insufficient chilling requirements in warm winters. Herbaceous taxa, such as Poaceae, advanced their flowering by an average of -0.13 days/year, equivalent to 1.3 days/decade, reflecting their sensitivity to rising temperatures and altered water availability. Notably, Rumex experienced a marked delay in flowering of -0.48 days/year, while Urticaceae advanced by +0.42 days/year.

Seasonal pollen integral displayed contrasting trends. Tree species such as Olea (average increase: +377.83 pollen grains/year, max: +1193.99 pollen grains/year in Jaén), Quercus (+180.81 pollen grains/year, max: +594.15 pollen grains/year in Córdoba), and Cupressus (+174.55 pollen grains/year, max: +853.45 pollen grains/year in Granada) showed significant increases. Conversely, certain herbaceous taxa, such as Poaceae (-11.89 pollen grains/year, min: -158.79 pollen grains/year in Badajoz), Amaranthaceae (-10.81 pollen grains/year, min: -30.07 pollen grains/year in Málaga) and Rumex (-6.67 pollen grains/year, min: -24.85 pollen grains/year in Badajoz), showed declining pollen loads, particularly in Mediterranean regions heavily affected by drought. In contrast, some taxa like Platanus displayed moderate increases averaging +101.11 pollen grains/year, demonstrating the complexity of pollen production responses to climatic variables.

Trends were not homogeneous across Spain. Southern regions exhibited more pronounced changes in flowering timing and intensity, aligning with greater climatic extremes. The observed trends in flowering timing and intensity underscore the complex ecological responses to climate change. Warming winters delay flowering in some taxa due to insufficient chilling, while rising temperatures and CO₂ levels could have driven increased pollen production in others, particularly in trees, but not so clear evidence in herbaceous. These findings highlight the need for continued pollen monitoring to mitigate the health impacts of allergenic pollen and to adapt agricultural practices to changing climatic conditions.

How to cite: Galan, C. and Oteros, J. and the Pollen team: Airborne Pollen Trends during the 3 last decades in Spain , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21517, https://doi.org/10.5194/egusphere-egu25-21517, 2025.

The rupture of Cupressaceae pollen grains significantly affects allergenic exposure and depends on specific hydrometeorological factors. This study analysed the main meteorological variables influencing pollen rupture in three cities in southeastern Spain during two pollen seasons (2019-2020 and 2020-2021). Using data from the Aerobiological Network of the Region of Murcia and standardised sampling methods (EN 16868), the study quantified total pollen concentrations, disrupted pollen (DP) levels and percentage of disrupted pollen (DPP).

The results reveal that the main factors influencing pollen rupture are related to water, specifically relative humidity and precipitation. Higher relative humidity levels were positively correlated with increased DP and DPP, indicating that relative humidity triggers structural changes in pollen grains. Precipitation showed a dual effect, simultaneously promoting pollen swelling and disruption while reducing airborne concentrations due to its wash-out effect. The influence of relative humidity aligns with the reproductive mechanisms of Cupressaceae, which rely on hydration for pollen tube formation. The percentage of disrupted pollen was significantly higher during periods of high relative humidity, with always positive correlations.

Statistical analyses confirmed that geographical characteristics and bioclimatic indices had a limited influence compared to localised factors such as urban ornamental flora and specific hydrometeorological conditions. Differences between the cities studied were also explored using hierarchical clustering dendrograms. These visualisations highlighted different clustering patterns based on pollen concentration and meteorological variables, highlighting the importance of localised urban vegetation management in influencing allergenic risks.

The results showed the dual role of precipitation in influencing airborne allergen exposure. This duality highlights the importance of considering both weather conditions and urban planning strategies to mitigate health risks. Management of ornamental Cupressaceae in urban areas, combined with monitoring of high relative humidity periods, could significantly reduce allergen exposure.

The integration of aerobiological and meteorological data networks provides a robust framework for allergen risk forecasting. Such systems can provide real-time alerts to vulnerable populations, especially during high pollen seasons. A better understanding of factors such as relative humidity and rainfall will improve public health responses and inform sustainable urban development policies.

How to cite: Moreno, J. M., Aznar, F., Negral, L., and Moreno, S.: Hydrometeorological drivers of Cupressaceae pollen rupture in southeastern Spain, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3092, https://doi.org/10.5194/egusphere-egu25-3092, 2025.

Cypress species and other members of the Cupressaceae family are widespread evergreen trees and shrubs, commonly used as ornamental plants. Some species, such as Mediterranean cypress (Cupressus sempervirens), Arizona cypress (Cupressus arizonica), and prickly juniper (Juniperus oxycedrus), widespread in Mediterranean, cause significant allergic reactions. This study aimed to develop a phenological model for Southern and Central Europe to predict the timing of cypress pollen release, enabling integration into atmospheric models for pollen dispersion forecasts. 

A key challenge is the microscopic similarity of all Cupressaceae pollen grains, which prevents species-level identification. Consequently, pollen observations report total Cupressaceae counts, complicating phenological modeling of allergenic species. 

For early-flowering species, thermal time models, such as growing degree days (GDD) or growing degree hours (GDH), are suitable. These models require defining a heat accumulation start date, a temperature threshold, and the cumulative heat required for flowering. Geographic variability and ornamental planting further influence flowering patterns, even between neighbouring locations. 

Pollen data were obtained from the European Aeroallergen Network (EAN), and temperature data from the ERA5 reanalysis dataset. Testing three start dates of the accumulation revealed that the autumn equinox was too early, while January 1st was too late, as J. oxycedrus and C. arizonica may flower before the new year. November 30th was optimal for detailed analysis. GDD/GDH was calculated using thresholds of 0°C, 1°C, 2°C, and 5°C, with normalized GDH (nGDH) yielding the most accurate results. 

When flowering onset was defined as 5% of the seasonal pollen index (SPI), the median GDH requirements ranged from 0.06–0.15 nGDH0 (SD 0.01–0.05) to 0.01–0.06 nGDH5 (SD 0–0.02). A 5°C threshold was too high leading to insufficient heat accumulation sensitivity, while 0°C was too low due to higher variability between years. Thresholds of 1°C and 2°C provided optimal accuracy with moderate inter-annual variability, making them suitable for forecasting the flowering onset. 

How to cite: Siljamo, P., Sofiev, M., and Palamarchuk, Y.: Forecasting the Onset of Cupressus Flowering in the Mediterranean Region , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15510, https://doi.org/10.5194/egusphere-egu25-15510, 2025.

Grapevine (Vitis vinifera L.) cultivation is one of the oldest, most widespread and important crops in the world. Downy mildew and grey mould are fungal diseases caused by the oomycete Plasmopara viticola and the ascomycete Botrytis cinerea, respectively. These diseases have a serious negative impact on viticulture, reducing the quantity and quality of harvests. Monitoring of variables affecting the environment-host-pathogen system in important viticulture areas is necessary for the control and prevention of these diseases. The aim of this study was to analyse the dynamics and behaviour of the atmospheric content of P. viticola and B. cinerea spores, as well as their relationship with different meteorological variables and the phenology of the grapevine.

The study was conducted between May and November 2023 in a vineyard belonging to the land of the Designation of Origin Uclés, D.O Uclés, located in the west of Cuenca province (Castilla-La Mancha region, central Spain). The area has a dry Mediterranean climate. Aerobiological sampling was carried out using a Hirst volumetric spore trap placed 2 metres above the ground in a vineyard of the Syrah grape cultivar. Samples were prepared and analysed following the methodology established by the Spanish Aerobiology Network. Phenological sampling was carried out weekly on 20 Syrah grapevines close to the spore trap, using an adaptation of the BBCH scale. Meteorological data were obtained from the Spanish Meteorological Agency (AEMET). The relationship between spore concentrations and meteorological variables was analysed using Spearman's non-parametric correlation test and Principal Component Analysis (PCA). Furthermore, an intradiurnal analysis of spore concentration was carried out.

A total of 894 spores/m³ of B. cinerea and 758 spores/m³ of P. viticola were obtained during the studied period. For B. cinerea, the daily peak spore concentration was on 18 October with 54 spores/m³, for P. viticola it was on 13 November with 74 spores/m³. The phenological stages with the highest daily spore concentrations for both pathogens were flowering, ripening and senescence of the grapevine. The spore concentration of both pathogens is positively influenced by relative humidity (RH), while temperature variables (mean, maximum and minimum) have a negative influence. Intradiurnal analysis showed that the highest spore concentrations occurred between midday (11:00-12:00) and early afternoon (16:00-17:00).

Flowering and ripening are critical stages for the development of these diseases. High temperatures and drought, characteristic of the summer period in areas with a dry Mediterranean climate, inhibit sporulation. However, diseases can develop before and after this period, when conditions are favourable. Progress in the knowledge of the environment-host-pathogen system in these areas will help to decide the most appropriate times for the application of phytosanitary treatments.

This work has been funded by the Ministry of Education, Culture and Sports of the JCCM, through the project SBPLY/21/180501/000172 and by the University of Castilla-La Mancha (UCLM) through the project 2022-GRIN-34507 and a pre-doctoral contract to Guillermo Muñoz-Gómez of the “Plan Propio I+D+I” of the UCLM.

How to cite: Muñoz Gómez, G., Jiménez Jiménez, E., Lara Espinar, B., Rodriguez-Arias, R. M., Rojo Úbeda, J., Fernández González, M., Rodríguez Rajo, F. J., Fernández González, F., and Pérez Badia, R.: Atmospheric spore content of the grapevine pathogenic fungi Plasmopara viticola and Botrytis cinerea in Mediterranean vineyards, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18361, https://doi.org/10.5194/egusphere-egu25-18361, 2025.

Pollen detection through automatic instruments has significantly improved over the recent years. Hirst-type traps start to be complemented with automatic instruments throughout Europe. Instead of the traditional identification of airborne pollen particles using light microscopy, data of the particles is collected and subsequently analysed by an AI-classifier. As an airflow-cytometer, SwisensPoleno instruments capture a fingerprint of each particle in-flight. Holography images, as well as fluorescence spectral data, as for SwisensPoleno Jupiter, are collected to classify measured pollen grains flowing through the device in real-time. Labelled datasets of each pollen-type of interest are required for the training of a new classifier. These are generated by collecting fresh and pure pollen from plants and aerosolizing it directly into a SwisensPoleno instrument under controlled conditions. 

New classifiers are evaluated by correlating concentrations determined by the automatic instrument with daily concentrations of co-located Hirst-type traps. To evaluate the performance of classifiers throughout Europe, multiple sites in different countries are assessed. Using results of the latest pollen classifier “Swisens (2025)”, based on holography images and fluorescence spectra, we show here how different locations of the SwisensPoleno and different input data can affect the resulting correlations to Hirst data, as well as the Mean Absolute Error (MAE). Differences in performance are expected between sites which are far apart, due to many factors such as differing geography, local climatic conditions and flora. Bad performance may arise from unknown interfering particles, only abundant at one specific site, and thus not included in the training datasets.

Our results demonstrate that this effect can also occur at a sub-regional scale, in sites only 30 km apart (Figure 1A), installed with the same instrument, and analysing data with the same classifier. Fraxinus pollen concentrations for P48 (Bolzano, Italy) correlate very well with a co-located Hirst (Figure 1B); that isn’t true for P46 (San Michele all’Adige, Italy), where strong interference from other particles is present during late May and beginning of June (Figure 1C). Interfering particles, similar to the target taxa, require site specific fine-tuning, e.g. in form of additional filters specifically excluding the interfering particles. In conclusion, while automatic pollen detection instruments show great promise in improving accuracy and efficiency, our findings highlight the importance of site-specific adaptations to address geographic and environmental variability, ensuring reliable performance across diverse locations.

How to cite: Schwendimann, A., Zeder, Y., Koch, K., Graf, E., Niederberger, E., Gottardini, E., Cristofori, A., Cristofolini, F., and Widmann, M.: The influence of local particles on classifier performance for pollen monitoring, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21490, https://doi.org/10.5194/egusphere-egu25-21490, 2025.

Background: Monitoring airborne pollen measurements depends on accurate and reproducible pollen recognition and analysis. The traditional volumetric Hirst method for pollen monitoring is based on European standards. This method demands skilled technicians, and it is a time-consuming process. Furthermore, this method has a 5–10 days delay in the data reported. To overcome these problems, a transition from manual to modern automatic methodologies is needed.  A Hirst-type trap has been used as a baseline and maintains historical time sequences of measured data to validate automatic samplers.

Methods: We compared both three-hourly and daily data of selected pollen types: Cupressus, Fraxinus, Pinaceae, Platanus, Poaceae, and Quercus, detected with a Hirst-type trap with a parallel retrieved concentration from three different automatic samplers: Pollen Sense APS-330, Hund BAA-500, and Swisens Poleno Jupiter. The pollen measurement campaign was conducted from 01 January 2024 to 03 June 2024 in Córdoba under the Mediterranean climate. The automatic samplers are based on different sampling and analysis methods, such as imaging-based identification, fluorescence spectroscopy and/or holographic imaging. We calculated Pearson's linear correlation coefficients (r) and daily ratio among Hirst and automatic measurements. 

Results: These results indicates the statistical significant differences between Hirst and automatic samplers (p ≤ 0.001) with strong correlation coefficient (r) for APS-330 data with r > 0.74 (3h) and r > 0.89 (daily) for Quercus, r > 0.77 (3h) and r >0.83 (daily) for Cupressus, and r > 0.65 (3h) and r > 0.70 (daily) for Poaceae ; the Hund BAA-500 data shows r > 0.63 (3h) and r > 0.84 (daily) for Cupressus, r > 0.55 (3h) and r > 0.56 (daily) for Poaceae at statistically highly significant (p ≤ 0.001), and for Platanus at moderately significant (p ≤ 0.01) with r > 0.50 (daily) and non-significant (p > 0.05) with r > 0.13 (3h). As with Swisens Poleno Jupiter, the weak correlation results with  r > 0.61 (3h) and r > 0.85 (daily) (p ≤  0.001) for Platanus, r > 0.38 (3h) and r > 0.67 (daily)  (p ≤ 0.001) for Poaceae, and r > 0.17 (3h) (p ≤ 0.001) and r > 0.36 (daily) (p ≤ 0.01) for Quercus. The average daily ratio for APS-330 was 2.31, for Hund BAA-500 was 2.77, and for Swisens Poleno Jupiter was 3.18.

Conclusion: This research study gives first insights into the Mediterranean environment. The results are from the pre-loaded algorithms and the companies did not include southern categories (e.g. Olea, Morus), which could lead to false positivity for already trained categories. We observed comparable concentrations provided by Hirst and both APS-330 and Hund BAA-500. The concentrations are not similar due to different measuring techniques of automatic samplers, we always noted a similar distribution curve, taking into account the use of scaling factors for the application of a homogenization index. However, further intercomparison studies, in particular, after the training of local categories and refinement of the algorithms based on digital reference datasets (DRD), the automatic samplers would show potential.

Keywords: Automated biomonitoring; Validation; Intercomparison studies; Airborne pollen

How to cite: Farooq, Q., López-Orozco, R., Martínez-Bracero, M., Galán, C., and Oteros, J.: Intercomparison studies and potential of pre-load algorithms for training and validating automated sampling systems in aerobiology, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4712, https://doi.org/10.5194/egusphere-egu25-4712, 2025.

Although bioaerosol particles are invisible to our eyes, they have a big impact in human life. Already at the beginning of the past century, the first attempts to detect the airborne pathogens causing damages in crops took place (Hirst, 1994), leading to the development of the Hirst trap (Hirst, 1952). From the agriculture field, the use of this trap jumped to the medical field, being used to monitor pollen and spores for the allergy patients. Since then, the use of manual pollen traps has spread around the world (Buters et al., 2018). However, the lack of experts and the laborious work of counting spores with a bright field microscope due to their small size and high numbers, has led to a scarcity of data on airborne fungal spores as compared to pollen. 

Recently, automatic monitors have been developed and are able to identify pollen in the air (Buters et al., 2022). Some automatic monitors have proven to perform well in pollen identification (Maya-Manzano et al., 2023) and are being used in official monitoring networks (Oteros et al., 2020, Sauvageat et al., 2020, Tešendić et al., 2020). These devices have brought a new opportunity to the identification of other bioaerosols, i.e., fungal spores. 

One of such instruments is the BAA500 (Hund GmbH). This instrument is designed as a cascade impactor. The air is sucked at high speed and particles between 4-80 µm arrive to a sticky plate at the end, where they are photographed with a camera attached to a microscope. Then, a software based in convolutional neural networks identifies the particles. The Validation tool (https://validation.pollenscience.eu/) is a quality control tool that allows to see the particles detected by the monitor. Within these images, we have confirmed that fungal spores are being captured by the device. However, a closer examination to evaluate their capture efficiency has not been done yet. 

In order to test the efficiency of the BAA500 in the capture of fungal spores, we collocated a Hirst trap next to an automatic monitor for five months (from May to October 2024) and compared the concentration of 5 fungal spore types, comprising a wide size range challenging the detection lower and upper limits of the instrument: Ganoderma, Cladosporium, Polythrincium, Epicoccum and Alternaria.

First results show that small (R²= 0.02, 0,08) and big (R²= 0.39) spores are under captured by the automatic device as compared to the Hirst trap, probably due to their size being in the limits of the cascade impactor, whereas medium-size spores correlate nicely with Hirst concentrations, showing a correlation of R²= 0.69 and 0.76. These results confirm the potential of the BAA500 to be used as fungi monitor for medium-size spores. Spores with a size close to the detection limit will need a scaling factor.

How to cite: González-Alonso, M., Žilka, M., Schmidt-Weber, C., and Buters, J.: Evaluating the capture efficiency of fungal spores with automatic monitors: the case of BAA500 (Hund GmbH), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21470, https://doi.org/10.5194/egusphere-egu25-21470, 2025.

Several automated pollen monitors have recently become available, most using conventional and/or machine-learning algorithms to detect pollen and classify their taxa. An international intercomparison campaign was organised by the EUMETNET AutoPollen Programme and the ADOPT COST Action in Munich (March–July 2021) (Maya-Manzano et al. 2023). The study showed that some automatic systems, especially those that have built-in correction factors to compensate for losses of sampling, detection and classification, agreed with the averaged pollen concentration of four manual Hirst-type measurements. The manual pollen counting method, relying on human operators, is still used today due to a lack of traceable metrological standards for pollen monitoring. Additionally, existing reference particle counters have been validated up to particle sizes around 20 µm only (Vasilatou et al. 2022). In this study, we evaluated the shake-the-box particle tracking/detection algorithm (Novara et al. 2023) to serve as a reference measurement of particle number concentration. A volume is illuminated with an expanded light sheet produced by a double-pulse laser, and four calibrated double-frame cameras record images of the particles inside this volume. The algorithm determines the position and velocity of each particle, allowing the measurement of particle number concentration directly in the air without sampling inlets that could influence the measurement.

Particle tracking was validated against the Inkjet Aerosol Generator at the Japanese National Metrology Institute NMIJ and the reference optical particle counter at METAS using an 11-D spectrometer (Grimm GmbH, Germany) as a transfer standard and size-certified polystyrene particles. Expanded uncertainties (coverage factor k=2) were 24 %, 10 %, and 7 % for particle sizes 15 μm, 20 μm, and 26 μm, respectively. The good agreement among the three methods shows that the shake-the-box particle tracking method can be applied as a reference for particle number concentration.

We used a laboratory-based method for characterising the performance of bioaerosol monitors as a whole unit (hardware plus identification algorithms) using the particle tracking method and, in a separate experiment, freshly sampled pollen. Experiments were carried out with the SwisensPoleno Jupiter, which combines light scattering, inline digital holography and ultraviolet laser-induced fluorescence with machine learning to classify different particles. For a pollen grain to be measured, it must be sampled, detected and correctly classified.  Each stage is subject to particle losses, leading to a measurement efficiency below 100 %. Particle tracking measurements of pollen (Pinus, Zea Mays) resulted in an average counting efficiency of about 43 %, neglecting particle losses in the Sigma-2 sampling head and issues with the classification of particles. The unit-to-unit variability of the Poleno instruments was 30 % based on measurement with three units. Independent experiments with Alnus glutinosa, Betula pendula and Corylus avellana showed that the major source of losses, however, originates from the pollen classification algorithm, which is trimmed to best correlate with Hirst measurements (currently the defacto reference for pollen monitoring). This highlights the need for an independent, standardised method for evaluating classifier losses.

How to cite: Horender, S., Giannakoudaki, C., Abt, R., Auderset, K., Crouzy, B., Erb, S., Erdogdu, O., Graf, E., Iida, K., Niederberger, E., Ou, L., Sakurai, H., Schmale, J., Wälchli, C., and Vasilatou, K.: Method for calibration of bioaerosol monitors based on reference pollen aerosols and imaging-based Lagrangian particle tracking as reference: the case of the Swisens Poleno, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11529, https://doi.org/10.5194/egusphere-egu25-11529, 2025.