Relationships between airborne pollen grains, wind direction and land cover using GIS and circular statistics.

Airborne bio-aerosol content (mainly pollen and spores) depends on the surrounding vegetation and weather conditions, particularly wind direction. In order to understand this issue, maps of the main land cover in influence areas of 10km in radius surrounding pollen traps were created. Atmospheric content of the most abundant 14 pollen types was analysed in relation to the predominant wind directions measured in three localities of SW of Iberian Peninsula, from March 2011 to March 2014. Three Hirst type traps were used for aerobiological monitoring. The surface area for each land cover category was calculated and wind direction analysis was approached by using circular statistics. This method could be helpful for estimating the potential risk of exposure to various pollen types. Thus, the main land cover was different for each monitoring location, being irrigated crops, pastures and hardwood forests the main categories among 11 types described. Comparison of the pollen content with the predominant winds and land cover shows that the atmospheric pollen concentration is related to some source areas identified in the inventory. The study found that some pollen types (e.g. Plantago, Fraxinus-Phillyrea, Alnus) come from local sources but other pollen types (e.g. Quercus) are mostly coming from longer distances. As main conclusions, airborne particle concentrations can be effectively split by addressing wind with circular statistics. By combining circular statistics and GIS method with aerobiological data, we have created a useful tool for understanding pollen origin. Some pollen loads can be explained by immediate surrounding landscape and observed wind patterns for most of the time. However, other factors like medium or long-distance transport or even pollen trap location within a city, may occasionally affect the pollen load recorded using an air sampler.

General trends in airborne pollen production and pollination periods at a Mediterranean site (Badajoz, southwest Spain).

BACKGROUND: The aim of this study was to determine trends in the airborne pollen concentration and pollination period for the principal sources of pollen in Badajoz (southwest Spain) over 15 years of monitoring (1994-2008). METHODS: Airborne pollen was monitored by continuous sampling with a Hirst volumetric sampler. Pollen trends were investigated by linear regression and correlation analysis using mean annual and monthly pollen concentrations. The aerobiological results were compared with meteorological data (temperature and rainfall). RESULTS: During the study period, the mean total annual rainfall was 66.2 mm lower than normal and the mean annual temperature 0.8 degrees C higher than normal. No temporal trend was found for total airborne pollen concentration, but differences were observed for monthly data, namely, an increase in January, February, and May and a decrease in March and June. For the different pollen types studied, there was a general trend toward increased values in the month with the highest values, and this trend seemed to be related to temperature.The beginning of the main pollen season occurred later, and the end occurred sooner; therefore, the main pollen season seems to be shorter. CONCLUSIONS: Our data reflect trends in the response of plants to changing rainfall stress patterns in Mediterranean countries, and these trends seem to be different from those of temperate countries. Nonetheless, a longer study period will be required to confirm these preliminary conclusions.

Differences in the spatial distribution of airborne pollen concentrations at different urban locations within a city.

BACKGROUND: The objective of the present work was to compare pollen counts at three different urban locations within a city to each other and to the counts from a fixed trap. This information could be useful to delimit zones in the urbanized part of the city according to the risk of allergic affections. METHODS: Aerobiological sampling using portable traps was carried out at three points in urban zones of the city of Badajoz (SW Spain) over one year at the same time as continuous sampling using a fixed trap at a point in the nonurban outskirts of the city. The sources of airborne pollen were studied by counting the trees in the streets and squares of the selected zones. A statistical analysis was performed of the differences between the portable and fixed traps and of the temporal and spatial variation in the city as a function of the distribution of the most important pollen sources. RESULTS: Forty-eight pollen types were identified with the fixed trap, and 28 with the portable traps. The grass, olive, and oak pollens come from almost exclusively external sources, there being no spatial differences in their concentrations in the city. Cypress pollen concentrations were much higher at the urban locations than at the fixed trap site. Plane tree pollen levels could be locally very high, reflecting the proximity of the source. Except for ornamental plants, pollen levels were lower at the urban locations than at the site on the outskirts of the city. CONCLUSIONS: (1) Using portable traps at different urban zones in a city could provide information about the spatial variation of atmospheric pollen levels. (2) A knowledge of the often widely variable distribution of ornamental plants with potentially allergenic pollen could be useful in indicating city zones with a greater or lesser incidence of potential pollinosis.

Pollen and spores in the air of a hospital out-patient ward.

BACKGROUND: Aerobiological studies of interest to the allergy specialist are routinely carried out using information from outdoor traps. However, most of our time is spent indoors and it is often the content of this air that is responsible for allergic phenomena. MATERIAL AND METHODS: The air of a hospital outpatient ward was analyzed using two portable volumetric aerobiological traps, one at floor level and the other at a height of 1 meter. Both spores and pollen grains were counted and their values were compared with those outside the building. RESULTS AND CONCLUSIONS: Twenty types of pollen grains were found. Their concentrations ranged from 2.7 and 25.1 grains/m3, with the most frequent being (in order) grasses, evergreen oak (holm and cork oaks), water plantain, and olive. Twenty two different types of spores were found with concentrations of between 175.0 and 1395.8 spores/m3 and the most frequent were Cladosporium, Ustilago and basidiospores. No significant differences were found between the floor level and the meter-high measurements. Comparison with outdoor levels showed that the three most abundant pollen types were correlated, with a ratio of 30:1 between indoor and outdoor levels. For the spores and fungi propagules, the indoor:outdoor ratio was highly variable, depending on the type. Thus, for Aspergillus-Penicillium spores, the concentration was even higher indoors than outdoors, although for most types, lower levels were found indoors, with a mean outdoor:indoor ratio of 4:1. We argue that this relationship reflects the presence of indoor spore sources. Rainfall was correlated with a decline in pollen levels and a rise in spore levels.

Pollen and spores in the air of a hospital out-patient ward

Background: Aerobiological studies of interest to the allergy specialist are routinely carried out using information from outdoor traps. However, most of our time is spent indoors and it is often the content of this air that is responsible for allergic phenomena. Material and methods: The air of a hospital outpatient ward was analyzed using two portable volumetric aerobiological traps, one at floor level and the other at a height of 1 meter. Both spores and pollen grains were counted and their values were compared with those outside the building. Results and conclusions: Twenty types of pollen grains were found. Their concentrations ranged from 2.7 and 25.1 grains/m3, with the most frequent being (in order) grasses, evergreen oak (holm and cork oaks), water plantain, and olive. Twenty two different types of spores were found with concentrations of between 175.0 and 1395.8 spores/m3 and the most frequent were Cladosporium, Ustilago and basidiospores. No significant differences were found between the floor level and the meter-high measurements. Comparison with outdoor levels showed that the three most abundant pollen types were correlated, with a ratio of 30:1 between indoor and outdoor levels. For the spores and fungi propagules, the indoor:outdoor ratio was highly variable, depending on the type. Thus, for Aspergillus-Penicillium spores, the concentration was even higher indoors than outdoors, although for most types, lower levels were found indoors, with a mean outdoor:indoor ratio of 4:1. We argue that this relationship reflects the presence of indoor spore sources. Rainfall was correlated with a decline in pollen levels and a rise in spore levels (AU)

Antecedentes: De forma rutinaria se hacen estudios aerobiológicos con interés alergológico basados en la información obtenida por captadores situados en el exterior, pero la mayor parte del tiempo de nuestra actividad la desarrollamos en interiores y es con frecuencia el contenido de este aire el responsable de fenómenos alérgicos. Material y métodos: El aire de una consulta hospitalaria ha sido analizado utilizando dos captadores aerobiológicos volumétricos portátiles, uno a nivel del suelo y otro a un metro de altura. Se contaron tanto los granos de polen como las esporas y su concentración se comparó con los valores en el exterior del edificio. Resultados y conclusiones: Se encontraron 20 tipos de granos de polen con una concentración entre 2,7 y 25,1 granos/m 3, siendo los más frecuentes por orden: gramíneas, encinas y alcornoques, llantenes y olivo; respecto a esporas se encontraron 22 tipos diferentes con una concentración entre 175,0 y 1395,8 esporas/m3, siendo las más frecuentes Cladosporium, Ustilago y basidiosporas. No se encontraron diferencias significativas entre la concentración a nivel del suelo y a un metro de altura. Comparando los valores del exterior y el interior los tres tipos polínicos más abundantes presentan una correlación entre ambas concentraciones, siendo la proporción exterior: interior de 30:1. Respecto a las esporas y propágulos fúngicos la relación exterior: interior es muy variable dependiendo de cada tipo, así, para las esporas Aspergillus-Penicillium la concentración ha sido incluso superior en el interior que en el exterior, aunque para la mayoría se presenta una disminución, siendo la relación media exterior: interior de 4:1; se argumenta esta relación en base a la presencia de fuentes internas de esporas. Se pone también de manifiesto la relación directa de las precipitaciones del exterior respecto a la concentración de polen, disminuyéndola, o de esporas, aumentándola (AU)

Influence of wind direction on pollen concentration in the atmosphere.

The daily pollen concentration in the atmosphere of Badajoz (SW Spain) was analysed over a 6-year period (1993-1998) using a volumetric aerobiological trap. The results for the main pollination period are compared with the number of hours of wind each day in the four quadrants: 1 (NE), 2 (SE), 3 (SW) and 4 (NW). The pollen source distribution allowed 16 pollen types to be analysed as a function of their distribution in the four quadrants with respect to the location of the trap. Four of them correspond to species growing in an irrigated farmland environment (Amaranthaceae-Chenopodiaceae, Plantago, Scirpus, and Typha), five to riparian and woodland species (Salix, Fraxinus, Alnus, Populus, and Eucalyptus), four to urban ornamentals (Ulmus, Arecaceae, Cupressaceae, and Casuarina), and three which include the most frequent pollen grains of widely distributed species (Poaceae, Quercus, and Olea). The results show that the distribution of the sources and the wind direction play a very major role in determining the pollen concentration in the atmosphere when these sources are located in certain quadrants, and that the widely distributed pollen sources show no relationship with wind direction. In some years the values of the correlations were not maintained, which leads one to presume that, in order to draw significant conclusions and establish clear patterns of the influence of wind direction, a continuous and more prolonged study will be required.