A new method for determining the sources of airborne particles.

Air quality is a major issue for humans owing to the fact that the content of particles in the atmosphere has multiple implications for life quality, ecosystem dynamics and environment. Scientists are therefore particularly interested in discovering the origin of airborne particles. A new method has been developed to model the relationship between the emission surface and the total amount of airborne particles at a given distance, employing olive pollen and olive groves as examples. A third-degree polynomial relationship between the air particles at a particular point and the distance from the source was observed, signifying that the nearest area to a point is not that which is most correlated with its air features. This work allows the origin of airborne particles to be discovered and could be implemented in different disciplines related to atmospheric aerosol, thus providing a new approach with which to discover the dynamics of airborne particles.

Daily variation patterns of airborne allergenic pollen in southwestern Spain.

The study was carried out using a Burkard sampler installed on the roof terrace of the School of Pharmacy, Seville, for two years (1995 and 1996). Eight pollen types described in the literature as having allergenic activity were chosen. They were Poaceae, Olea europaea, Chenopodiaceae/Amaranthaceae, Plantago, Rumex, Urticaceae (including Parietaria), Cupressaceae, and Platanus hispanica. The types were grouped according to the similarity of their pattern of intradiurnal variation in pollen concentration. The following associations were established by multivariate analysis: Urticaceae and Chenopodiaceae/Amaranthaceae (appearing mainly between 11:00 and 20:00), Olea europaea and Plantago (12:00 to 19:00), Poaceae and Rumex (appearing throughout the day), and Cupressaceae and Platanus hispanica (8:00 to 14:00). The patterns of intradiurnal variation were similar both years for each type, despite the fact that the two years were climatologically different (1995 was dry and 1996 wet). We conclude that these behavior patterns are endogenous to the plants, and are hardly affected by meteorological parameters.

Airborne grass (Poaceae) pollen in southern Spain. Results of a 10-year study (1987-96).

This work reports an exhaustive study of the aerobiology of the Gramineae in Seville, Spain, which is typical of coastal Mediterranean areas. Sampling was done with a Cour trap installed on the roof terrace of the School of Pharmacy, Seville, from 1987 to 1996, both inclusive. The climatic pattern of that period was characterized by two exceptionally wet years (1989 and 1996), between which were 5 consecutive years of drought (1990-5). This typically Mediterranean climate affects grass aerobiology. The annual amounts of total grass pollen are low, never exceeding 2500 grains/m3. The start, length, and intensity of the pollen season are significantly correlated with preseasonal meteorologic factors (precipitation and temperature), but intraseasonal meteorologic conditions have no effect on the three variables. The relationships are stated by three equations that, while further years of observations are anticipated, can be considered models to forecast the characteristics of the pollen season: the starting date depends on the mean temperatures of January and February, and the length and intensity of the season depend on the rainfall between the beginning of January and the starting date of the season. For the study period, the weekly concentrations (pollen curves) throughout the year showed no typical pattern of variation over the years, so that it was impossible to make mid- and long-term forecasts of the variation in weekly concentration. The most noteworthy aspects of grass pollen curves are a long pollen season, which starts in February or March and lasts until September or October; peaks of higher concentration (> 100 grains/m3) in May and June, associated with increases in temperature and absence of precipitation; and other peaks in the summer months that may be as high as the spring peaks.

Aerobiological study of Chenopodiaceae and Amaranthaceae in the Mediterranean area of southwestern Spain.

The study area is characterized by a maritime Mediterranean climate, abundant presence of Chenopodiaceae in the vegetation, and a high incidence of pollinosis caused by the pollen of this family. A Hirst-type sampler was used to determine pollen concentrations in the air of the city of Huelva during 3 consecutive years (1995-1997). The total annual amount of Chenopodiaceae-Amaranthaceae pollen was between 10.59% and 6.28% of the pollen spectrum of the city, depending on the year. The annual pattern of variation in pollen concentration (5-day means) was very similar in the 3 years, and no statistically significant differences were found between years. This pattern is characterized by concentrations not exceeding 20 grains/m3 between April and the beginning of August, with an obvious seasonal variation in the second half of August and September, when the 5-day mean concentrations exceeded 40 grains/m3 and the daily maxima exceeded 100 grains/m3. This coincided with the flowering of most of the species in the group. The meteorological parameters with a statistically significant effect on daily pollen concentration during the pollen season (August 15 to September 20) included mean temperature and south wind (positive correlations) and relative humidity of the air (negative correlation). The highest intradiurnal concentrations were found between 10:00 a.m. and 5:00 p.m.

Olea europaea airborne pollen in southern Spain.

BACKGROUND: Olea europaea pollen is one of the most abundant constituent pollens in Seville (southern Spain). It is responsible for many documented cases of pollinosis in the area. OBJECTIVE: To contribute to the useful knowledge of Olea europaea for allergists. METHODS: The number of Olea europaea pollen grains in the atmosphere was recorded during 8 consecutive years (1987-1994), using a Cour collector. RESULTS: The concentration of Olea europaea pollen was as high as 250 to 1015 grains/m3 only during 1 or 2 weeks in April and May. Overall annual production of O. europaea pollen alternated between years. The beginning of the main pollination period was related to the mean temperature of the preceding months (February and March). Pollination occurred when the mean temperature in both months was higher than 14 degrees C; conversely it was delayed when the mean temperature was lower. Main pollination period length depended upon both temperature and rainfall during this period: temperatures higher than 19.5 degrees C and absence of rainfall shortened the main pollination period, while lower temperatures (15 to 18 degrees C) together with rainfall rates above 100 mm lengthened it. CONCLUSIONS: Climatic variables such as preceding mean temperature and rainfall impact on pollen anthesis of Olea europaea affect onset and duration of pollination. A consideration of yearly cycles of pollen production as well as these variables should allow pollen forecasting.

Variations of airborne summer pollen in southwestern Spain.

The fact that a considerable proportion of pollen allergy sufferers have an upsurge of symptoms in summer prompted us to study the airborne pollen types present in the air of Huelva (southwestern Spain) during the months of July, August and September. A Cour-type pollen sampler was installed in the center of the city. In these months of elevated climatological dryness (high temperatures and almost complete absence of rain), 26 different pollen types were detected (results from four years of observation: 1989-1992). Quantitatively outstanding were Amaranthaceae/Chenopodiaceae, Eucalyptus, Gramineae (Poaceae), Helianthus and Ligustrum (comprising 86.06% of the pollen measured). Of these types, only extracts of Gramineae and Amaranthaceae are included in the skin tests and immunotherapy practiced in the region. Given the allergic potential of the pollen of Ligustrum, Helianthus, Eucalyptus and Palmaceae, we performed aerobiological evaluations, which may be useful when diagnosing summer pollen allergies.

Latitudinal study of allergenic pollen in two Spanish cities.

A comparative study was performed on the pollen spectra in 1990 in two Spanish cities with different vegetation and climate, one situated on the south coast (Huelva) and the other in the north and inland (Palencia). The flowering of Alnus and Fraxinus occurred earlier in the north, while that of grasses (Plantago, Poaceae and Urticaceae) occurred earlier and lasted longer in the south, with milder temperature conditions resulting in no fall in pollen content between winter and spring. The absence of olive pollen in Palencia reaffirms that the pollen spectrum of a locality is a consequence of the surrounding vegetation. The geographical situation of Palencia, in the interior of Spain, results in higher percentages of Poaceae and Quercus. The enormous pollution of Huelva favors the greater development of the Urticaceae family and the greater presence of its pollen in the air.

Pollen calendar of Seville and its relation to allergies.

We have carried out a study on the annual and weekly variation of airborne pollen in the air of Seville (Andalusia, Southern Spain) during 3 consecutive years using two Cour's collectors. We provide the pollen calendar of this city, which shows the annual distribution of the most important pollen types. Our results led us to check the validity of the pollen extracts usually used at the hospitals of the city to diagnose pollinosis.