Changes in concentration of Alternaria and Cladosporium spores during summer storms

Fungal spores are known to cause allergic sensitization. Recent studies reported a strong association between asthma symptoms and thunderstorms that could be explained by an increase in airborne fungal spore concentrations. Just before and during thunderstorms the values of meteorological parameters rapidly change. Therefore, the goal of this study was to create a predictive model for hourly concentrations of atmospheric Alternaria and Cladosporium spores on days with summer storms in Szczecin (Poland) based on meteorological conditions. For this study we have chosen all days of June, July and August (2004–2009) with convective thunderstorms. There were statistically significant relationships between spore concentration and meteorological parameters: positive for air temperature and ozone content while negative for relative humidity. In general, before a thunderstorm, air temperature and ozone concentration increased, which was accompanied by a considerable increase in spore concentration. During and after a storm, relative humidity increased while both air temperature ozone concentration along with spore concentrations decreased. Artificial neural networks (ANN) were used to assess forecasting possibilities. Good performance of ANN models in this study suggest that it is possible to predict spore concentrations from meteorological variables 2 h in advance and, thus, warn people with spore-related asthma symptoms about the increasing abundance of airborne fungi on days with storms.     

Correlation of spring spore concentrations and meteorological conditions in Tulsa, Oklahoma

Different spore types are abundant in the atmosphere depending on the weather conditions. Ascospores generally follow precipitation, while spore types such as Alternaria and Cladosporium are abundant in dry conditions. This project attempted to correlate fungal spore concentrations with meteorological data from Tulsa, Oklahoma during May 1998 and May 1999. Air samples were collected and analyzed by the 12-traverse method. The spore types included were Cladosporium, Alternaria, Epicoccum, Curvularia, Pithomyces, Drechslera, smut spores, ascospores, basidiospores, and other spores. Weather variables included precipitation levels, temperature, dew point, air pressure, wind speed, wind direction and wind gusts. There were over 242.57 mm of rainfall in May 1999 and only 64.01 mm in May 1998. The most abundant spore types during May 1998 and May 1999 were Cladosporium, ascospores, and basidiospores. Results showed that there were significant differences in the dry-air spora between May 1998 and May 1999. There were twice as many Cladosporium in May 1998 as in May 1999; both ascospores and basidiospores showed little change. Multiple regression analysis was used to determine which meteorological variables influenced spore concentrations. Results showed that there was no single model for all spore types. Different combinations of factors were predictors of concentration for the various fungi examined; however, temperature and dew point seemed to be the most important meteorological factors. Received: 5 July 2000 / Revised: 20 December 2000 / Accepted: 22 December 2000     

A comparative study of hourly and daily relationships between selected meteorological parameters and airborne fungal spore composition

Air sampling was conducted in Szczecin (Poland) throughout April–September 2013. The final data set included 177 daily and 4248 hourly samples. The total of 21 types of spores, which occurred in a number >10 in the season, were taken into account. The following meteorological parameters were analyzed: air temperature, relative humidity, precipitation and wind speed. Effects of individual weather parameters on hourly and daily concentrations of different fungal spore types were examined using Spearman’s rank association test, whereas effects of complex of meteorological factors on hourly and daily compositions of spore were assessed using detrended correspondence analysis (DCA) and redundancy analysis (RDA). Airborne fungal spore distribution patterns in relation to meteorological variables were determined by RDA, after DCA results detected a linear structure of the spore data. The RDA results obtained indicated that all the applied variables accounted for 20 and 22% of the total variance in the hourly and daily spore data, respectively. The results of stepwise forward selection of variables revealed all included hourly and daily meteorological variables were statistically significant. The largest amount of the total variance in the spore composition was explained by the air temperature in both cases (16%). Multivariate ordination did not show large differences between the hourly and daily relationships (with exception of wind speed impact), while the differences between simple hourly and daily correlations were more clear. Correlations between daily values of variables were in most cases higher than between hourly values of variables.     

Hourly predictive artificial neural network and multivariate regression tree models of <Emphasis Type="Italic">Alternaria</Emphasis> and <Emphasis Type="Italic">Cladosporium</Emphasis> spore concentrations in Szczecin (Poland)

A study was made of the link between time of day, weather variables and the hourly content of certain fungal spores in the atmosphere of the city of Szczecin, Poland, in 2004–2007. Sampling was carried out with a Lanzoni 7-day-recording spore trap. The spores analysed belonged to the taxa Alternaria and Cladosporium. These spores were selected both for their allergenic capacity and for their high level presence in the atmosphere, particularly during summer. Spearman correlation coefficients between spore concentrations, meteorological parameters and time of day showed different indices depending on the taxon being analysed. Relative humidity (RH), air temperature, air pressure and clouds most strongly and significantly influenced the concentration of Alternaria spores. Cladosporium spores correlated less strongly and significantly than Alternaria. Multivariate regression tree analysis revealed that, at air pressures lower than 1,011 hPa the concentration of Alternaria spores was low. Under higher air pressure spore concentrations were higher, particularly when RH was lower than 36.5%. In the case of Cladosporium, under higher air pressure (>1,008 hPa), the spores analysed were more abundant, particularly after 0330 hours. In artificial neural networks, RH, air pressure and air temperature were the most important variables in the model for Alternaria spore concentration. For Cladosporium, clouds, time of day, air pressure, wind speed and dew point temperature were highly significant factors influencing spore concentration. The maximum abundance of Cladosporium spores in air fell between 1200 and 1700 hours.     

<Emphasis Type="Italic">Alternaria</Emphasis> spores in the atmosphere of Sydney,Australia, and relationships with meteorological factors

Alternaria spores are found in the atmosphere in many locations around the world. They are significant from a human health perspective because they have been known to trigger allergic respiratory disease such as asthma and hay-fever. The presence of Alternaria spores in the atmosphere has been related to meteorological factors in past studies, but this has not been done previously in Sydney, Australia. This paper reports the results of such a study in Sydney. Alternaria spore concentration data for the period 19 August 1992 to 31 December 1995 were examined with meteorological data for the same period. The daily Alternaria spore concentration was compared to the meteorological data for the same day and for up to 3 days previously. The analysis methods were Spearmans rank correlation and multiple regression. Alternaria spores appear in the atmosphere of Sydney year-round, although they peak over spring, summer, and autumn. A number of meteorological factors, including mean, minimum, and maximum, temperature, dew point temperature, and air pressure, are significantly correlated with the atmospheric concentration of Alternaria spores. Some of these meteorological variables (temperature and dew point temperature) show significant correlations with a 1, 2, and 3 day lag, as well as for the same day. Regression models indicate that up to 31.1% of the variation in Alternaria spore concentration can be explained by meteorological factors. There is potential for the results of this study to be used by public health authorities in the prediction of Alternaria spore concentrations in Sydney.     

Airborne Alternaria spores in SE Spain (1993-98)

The annual, seasonal and hourly distribution of Alternaria spores in the air of Murcia, SE España, was studied on a six-year period. The relationships between Alternaria spore concentrations and meteorological factors were investigated. Alternaria is a late afternoon taxon in the Murcia city, with maximum spore concentrations occurring between 13.00h and 21.00h. Alternaria spores are present in the atmosphere throughout the year, with a main spore season extending from March to October, and showing two peaks as a consequence of the summer drop in concentration. Alternaria spore concentrations correlate well with Poaceae and Chenopodiaceae pollen counts, suggesting these plants could be important hosts, but not the only ones, because many crops are growing just when peaks occur. Low wind velocities favoured high spore counts. Correlation with temperature was positive in five of the six years. Mean temperature is the factor which best explain spore levels. The best prediction model obtained explains 74% of the observed variance in Alternaria levels (in a five steps scale) by using mean temperature alone.     

Airborne <Emphasis Type="Italic">Aspergillus</Emphasis> and <Emphasis Type="Italic">Penicillium</Emphasis> in the atmosphere of Szczecin, (Poland) (2004–2009)

The investigation into airborne fungal spore concentrations was conducted in Szczecin (Poland) between 2004 and 2009. The objective of the studies was to determine a seasonal variation in concentrations of amerospores on the basis of meteorological parameters. The presence of spores in Szczecin was recorded using a volumetric method. Fungal spores were present in the air in high numbers in late summer and early autumn. The highest concentrations were noted in September, October and November. The peak period was recorded in August, September, October and November. The highest annual number of spores occurred in 2005 and 2007 and the lowest in 2006. High values of daily concentration of amerospores occurred during the afternoon and late at night. In 2005 and 2007 the late-night maximum was overdue about 1 or 2 h. For daily values of dew point temperature and relative humidity, the coefficients were positive, significant for p = 0.001 and ranged from 0.342 to 0.258. The average wind speed was positively correlated for p = 0.01 and the coefficient was 0.291. The similar relations were noted for hourly values of spore concentrations for p = 0.05, p = 0.01 and p = 0.001. For these spore types, the dew point temperature and relative humidity appeared to be the most influential factor.     

The influence of meteorological parameters on <Emphasis Type="Italic">Alternaria</Emphasis> and <Emphasis Type="Italic">Cladosporium</Emphasis> fungal spore concentrations in Beja (Southern Portugal): preliminary results

Introduction Fungal spores constitute an important fraction of bioaerosols in the atmosphere. Objectives To analyse the content of Alternaria and Cladosporium spores in the atmosphere of Beja and the effect of meteorological conditions on their concentrations. Methodology The daily and hourly data of Alternaria and Cladosporium fungal spores concentration in the atmosphere of Beja were monitored from April 12, 2012 to July 30, 2014, based on the Portuguese Aerobiology Network methodology. The influence of meteorological conditions on the studied types of fungal spore concentrations was assessed through Spearman’s correlation analysis. Results During the study period, 20,741 Alternaria spores and 320,862 Cladosporium spores were counted. In 2013, there were 5,822 Alternaria spores and 123,864 Cladosporium spores. The absolute maximum concentrations of Alternaria and Cladosporium spores were recorded on November 8, 2013, with 211 and 1301 spores/m³, respectively. Temperature, insolation and wind direction parameters showed a positive correlation with Alternaria and Cladosporium spore levels, while relative humidity and precipitation presented a negative correlation, which is statistically significant. Wind speed only showed a statistically significant positive correlation in terms of Alternaria spore levels. Conclusion Alternaria and Cladosporium spores are present in the atmospheric air of Beja throughout the year, with the highest concentration period occurring during spring and autumn. There was a clear effect of meteorological parameters on airborne concentrations of these fungal spores.     

Airborne basidiospores of Coprinus and Ganoderma in a Caribbean region

The present study sought to examine Coprinus and Ganoderma airborne spore counts, analysing seasonal variations, the influence of meteorological variables and intraday behaviour with a view to charting the aerobiological dynamics of both genera in Havana (Cuba) during a 2-year period (November 2010–October 2012). A Hirst-type volumetric air sampler was used as sampling methodology. The spores registered in the air were identified and counted following the model proposed by the Spanish Aerobiological Network based on two longitudinal transects along the slides. Coprinus spores outnumbered those of the Ganoderma (28,468 annual total spores vs. 1,921 spores). Moreover, both genera were recorded in the atmosphere on a large number of days over the two-year study period, with daily maximum concentrations in the rainy months. The daily maximum value for Coprinus was 880 spores/m³ (30 September 2011), whereas for Ganoderma 44 spores/m³ (4 September 2011). The analysis of the Spearman correlation coefficient showed a significant positive correlation of the airborne Coprinus and Ganoderma spores with the temperature, relative humidity and rainfall, whereas the degree of association is negative with the wind speed. Regarding the intraday behaviour, both basidiospores were more abundant in the atmosphere during the night, with a maximum peak at 5–6 a.m.     

The effects of meteorological factors on the occurrence of <Emphasis Type="Italic">Ganoderma</Emphasis> sp. spores in the air

Ganoderma sp. is an airborne fungal spore type known to trigger respiratory allergy symptoms in sensitive patients. Aiming to reduce the risk for allergic individuals, we analysed fungal spore circulation in Szczecin, Poland, and its dependence on meteorological conditions. Statistical models for the airborne spore concentrations of Ganoderma sp.—one of the most abundant fungal taxa in the area—were developed. Aerobiological sampling was conducted over 2004–2008 using a volumetric Lanzoni trap. Simultaneously, the following meteorological parameters were recorded: daily level of precipitation, maximum and average wind speed, relative humidity and maximum, minimum, average and dew point temperatures. These data were used as the explaining variables. Due to the non-linearity and non-normality of the data set, the applied modelling techniques were artificial neural networks (ANN) and mutlivariate regression trees (MRT). The obtained classification and MRT models predicted threshold conditions above which Ganoderma sp. appeared in the air. It turned out that dew point temperature was the main factor influencing the presence or absence of Ganoderma sp. spores. Further analysis of spore seasons revealed that the airborne fungal spore concentration depended only slightly on meteorological factors.     

A 10-year study of <Emphasis Type="Italic">Alternaria</Emphasis> and <Emphasis Type="Italic">Cladosporium</Emphasis> in two Polish cities (Szczecin and Cracow) and relationship with the meteorological parameters

Alternaria and Cladosporium spores belong to the most frequent and allergenic particles in bioaerosol in the temperate climate. The investigation of Alternaria and Cladosporium spore concentrations was performed in two cities in Poland, Szczecin and Cracow, in 2004–2013. The meteorological parameters taken to assess their impact on fungal spores were average, maximum and minimum temperature, relative humidity and average wind velocity. In order to reveal whether changes in dynamics of spore seasons are driven by meteorological conditions, ordination methods were applied. Canonical correspondence analysis was used to explore redundancy among the predictors (meteorological parameters). Prior to ordination analyses, the data were log(x)-transformed. Concentrations of Alternaria and Cladosporium spores were significantly higher in Szczecin comparing to Cracow, but it was also observed the decreasing trend in the spore concentrations in Szczecin. As regards temperature, it was higher in Cracow and was still increasing in the studied years. Relative humidity and wind velocity were significantly lower in Cracow. In Szczecin meteorological conditions did not explain changes in spore season characteristics (insignificant redundancy analysis models), while in Cracow’s redundancy analysis models indicated that spore season parameters were in over 40 % determined by meteorological conditions, mainly air temperature and wind velocity. If they increase, the peak value, total number of spores and their average concentrations in a season will also increase.     

Study of airborne fungal spores in Madrid, Spain

The concentration of fungal spores in the atmosphere of Madrid was recorded and analyzed for the year 2003. Airborne spores were sampled continuously with a Hirst-type spore trap located on the roof of a building of the School of Pharmacy, at about 8 m above ground level. Correlation between the mean daily spore concentrations and meteorological variables were explored by means of Spearman’s correlation analyses. Seventy spore types were identified, of which the most numerous were Cladosporium, Aspergillaceae (conidia), Coprinus, Agaricales (basidiospores), Ustilago (teliospores) and Pleospora (ascospores). These six types of spores represented more than 70% of the total. Cladosporium represented 41% of the total fungal spores, while Ustilago spores, the concentrations of which in May and June exceeded 47% of the monthly total spore count, constituted the second most important group. Spores reached their highest concentrations in the spring months, and in the autumn, mainly in October. A␣positive significant correlation was found between airborne spore counts and temperature and relative humidity. The results provide a picture of the spectrum of airborne fungal spores present in the atmosphere of Madrid and of the `peak' periods of their presence. Future studies will provide more detailed information on the seasonal dynamics of the spores most frequently found in the air as well as on the extent to which atmospheric conditions influence their release, dispersion and sedimentation processes.     

The effect of meteorological factors on the daily variation of airborne fungal spores in Granada (southern Spain)

A study was made of the link between climatic factors and the daily content of certain fungal spores in the atmosphere of the city of Granada in 1994. Sampling was carried out with a Burkard 7-day-recording spore trap. The spores analysed corresponded to the taxa Alternaria, Ustilago and Cladosporium, with two morphologically different spore types in the latter genus, cladosporioides and herbarum. These spores were selected both for their allergenic capacity and for the high level of their presence in the atmosphere, particularly during the spring and autumn. The spores of Cladosporium were the most abundant (93.82% of the total spores identified). The Spearman correlation coefficients between the spore concentrations studied and the meteorological parameters show different indices depending on the taxon being analysed. Alternaria and Cladosporium are significantly correlated with temperature and hours of sunlight, while Ustilago shows positive correlation indices with relative humidity and negative indices with wind speed. Received: 16 April 1998 / Revised: 27 September 1999 / Accepted: 27 October 1999     

Summer airborne mycoflora of Timişoara (Romania) and relationship to meteorological parameters

The present aeromycological investigation was undertaken to study atmospheric fungal spores in Timi?oara (western Romania). This study was carried out using a Hirst type volumetric sampler. The study revealed the existence of a rich airborne mycoflora. The atmospheric fungal spores were classified and evaluated into three groups (‘major’, ‘minor’ and ‘sporadic’) depending upon their catch percentage in the air. Cladosporium/Fusarium/Leptosphaeria-group, Alternaria, Helminthosporium airborne fungal spores and airborne fungal fragments regularly recorded (frequency 100% of days). Cladosporium accounted for 81.09% of the outdoor fungal spores. The airborne fungal fragments have been identified as abundant in our geographic area. Spearman’s correlations were applied to meteorological parameters and airborne fungal spore concentrations. In addition, correlations were calculated between the fungal spore concentrations and the meteorological variables from the previous day. A total of eleven weather factors were selected for this investigation. Following Spearman’s correlations, I identified two patterns of behaviour: most of the airborne fungal spores prefer cloudiness, lower near-surface soil temperature, lower atmospheric pressure, higher relative humidity and precipitation (pattern A) while other spore concentrations favour increased sunshine, higher near-surface soil temperature and dry conditions (pattern B). The behaviour of some fungal spores during the warm season has proven unclear (pattern C). This study demonstrates the need for investigations throughout the year and the evaluation with complementary statistical methods, regarding the correct interpretation of airborne mycoflora relationships with meteorological parameters.     

Analysis of environmental factors and their effects on fungal spores in the atmosphere of a tropical urban area (San Juan,Puerto Rico)

In Puerto Rico, respiratory diseases affect a significant percentage of the population, and it is possible that the environmental factors unique to the island, such as easterly winds, dense vegetation, and high humidity, may increase the concentration of airborne biological particulates that could distress susceptible individuals. As most studies characterized fungal spores and pollen in temperate zones, we wanted to describe their concentrations in a tropical zone. The Allergenco^® (MK3) spore trap was used to monitor airborne spores and pollen concentrations for 12 months starting on May 2005. During the length of the study, silicone grease-coated microscope slides captured 12 impacts daily, which were then stained with calcofluor and observed under the microscope with bright field and ultraviolet light. Atmospheric conditions were recorded with the Precision Weather Station^®. Precipitation, dew point, and relative humidity promote the presence of fungal spores in San Juan throughout the year, with basidiospores being the most frequent. Spore concentrations were higher during the early morning hours all the year around. Wind and gusts were dispersal factors, and humidity and the dew point favored the release of spores into the atmosphere. In contrast to spores, pollens were not found to be affected by any of the meteorological factors and no distinctive patterns were found. Describing how airborne spores and pollens, many of which have allergenic potential, behave in the tropics, such as in San Juan, Puerto Rico, could be used to design preventive measures for the benefit of the sensitized population. Information about the presence and abundance of aeroallergens will assist in the diagnosis of allergic rhinitis and asthma on the island.     

Long term trends in outdoor <Emphasis Type="Italic">Aspergillus/Penicillium</Emphasis> spore concentrations in Derby,UK from 1970 to 2003 and a comparative study in 1994 and 1996 with the indoor air of two local houses

Aspergillus/Penicillium spore concentrations have been monitored in Derby since 1970 using a volumetric spore trap, with full year data from 1991. In addition a short comparative study with the indoor air was undertaken at two local houses in 1994 and 1996. Aspergillus/Penicillium spores were present in the Derby air throughout the year and often reached maximum monthly cumulative concentrations in the autumn, although they were occasionally the dominant spores in the winter when total spore concentrations were low. Very high daily concentrations could occur at any time of year with a count of over 5000 recorded. Peak days in the autumn and winter of 2002–2003 were examined on a two hourly basis showing higher concentrations in the middle of the day. There was a positive correlation of cumulative monthly Aspergillus/Penicillium totals with maximum temperature. Indoor data from the two houses was examined on a daily basis and compared with simultaneously sampled outdoor daily spore concentrations. The elevated Aspergillus/Penicillium spore levels found in the older of the two houses occurred on all of the days sampled. Compared to the modern house, the Aspergillus/Penicillium spore concentrations in the old house represented a much higher percentage of the total spore count than in the modern one. The correlation between outdoor Aspergillus/Penicilliumspore concentrations and the indoor air of the old house was 0.62, whereas in the modern house it was 0.31. Peak hourly samples of Aspergillus/Penicillium spore counts occurred at times of greatest activity.     

Daily variations ofAlternaria spores in the city of Murcia (semi-arid southeastern Spain)

Annual variations in the abundance ofAlternaria spores were related to the length of the spore period for data from Murcia (southeastern Spain). To understand the relationship between the number of spores and climatic factors,Alternaria spore counts for March 1993 to February 1994 were examined by means of correlation and regression analyses with fourteen different weather parameters. The results indicated that there was a tendency forAlternaria spore concentrations to increase with increases in temperature, wind speed and hours of sunshine. Negative correlations were observed with air pressure, wind direction and humidity. Theoretical curves forAlternaria spore counts are given in relation to temperatures during the period studied.     

Seasonal and Diurnal Variation of Airborne Basidiomycete Spore Concentrations in Mexico City

Seasonal and diurnal changes in concentrations of airborne basidiomycete spores (basidiospores, rusts, smuts) were studied, using Burkard volumetric spore traps, in two areas of Mexico City with different degrees of urbanization and related to changes in climatic variables through 1991. Basidiomycete spores formed a large component of the total airborne fungal spore load in the atmosphere of Mexico City. They were the second most abundant spore type after Deuteromycotina (Hyphomycetes), forming 32% of the total fungal spores trapped in an urban-residential area and 28% in an urban-commercial area. The most abundant basidiomycete spores were basidiospores although smut-type spores were trapped on more days than basidiospores and rusts on fewer. Basidiospores occurred in concentrations up to 2,000 spores m-3 in the urban-residential area. Basidiospores showed a marked seasonal distribution, especially in the southern area, with their greatest abundance during the wet season. The correlation coefficients associated with regressions between basidiospore concentration and some environmental factors were increased when a lag period of 2 to 4 days was used between environmental measurements and the day of spore collection. Basidiospore concentrations exceeded the 75 percentile concentration (>400 spores m^-3) most often when rainfall was up to 6 mm and relative humidity was >70%. Basidiospores showed a diurnal periodicity with greatest concentrations in the early morning. The most common basidiospore type was Coprinus which formed 67% of basidiospores trapped in the southern area and 63% in the central area. Smut spores were trapped on 87% of days through the year while rust spores occurred in only 35%. Both rusts and smuts were present in only small concentrations.     

Influence of urban climate upon distribution of airborne Deuteromycete spore concentrations in Mexico City

 The effect of an urban climate upon the spatial and temporal distribution of Deuteromycete spores was studied during 1991 using Burkard volumetric spore traps in two areas of Mexico City with different degrees of urbanization. Deuteromycete conidia formed the largest component of the total airborne fungal spore load in the atmosphere of Mexico City, contributing 52% of the spores trapped in an urban-residential area (southern area) and 65% of those in an urban-commercial area (central area). Among the most common spore types, Cladosporium and Alternaria showed a marked seasonal periodicity with significant differences in concentration (P<0.05) between the dry and wet seasons. Maximum conidial concentrations were found during the end of the wet season and the beginning of the cool, dry season (October–December). Daily mean concentrations of the predominant airborne spore types did not differ significantly between the southern and central areas. Daily mean spore concentrations were significantly correlated (P<0.05) in southern and central areas with maximum temperature (south, r = –0.35; central, r = –0.40) and relative humidity (south, r = 0.43; central, r = 0.29) from the previous day. Moreover, multiple regression analysis of spore concentrations with several meteorological factors showed significant interactions between fungal spores, relative humidity and maximum temperature in both areas. The diurnal periodicity of Cladosporium conidia characteristically showed two or three peaks in concentration during the day at 0200–0400, ∼ 1400 and 2000–2200 hours, while that of Alternaria showed only one peak (1200 to 2000 hours) in both areas. Maximum concentrations of these spores generally occurred 2–4 h earlier in the southern than in the central area. The lag in reaching maximum concentrations in the central area probably resulted from differences in the local conditions between the study areas, and from spores transported aerially into the city from distant sources. The analysis of maximum hourly concentrations of Cladosporium and Alternaria spores during 1 month of the dry season (February), and another month of the wet season (September) showed significant differences between the two study areas. Environmental factors and sources (green areas) affected diurnal changes in conidial concentration in the southern area (urbanization index, UI, 0.25), but not in the central area (UI 0.97). In general, spore concentrations were greatest in the southern area when relative humidities were low, and temperatures and wind velocities were high. It was difficult to establish effects of climatic factors on the spore concentration in the city centre. This probably results from the large amounts of air pollution, the heat island phenomenon, and from the distant origin of trapped conidia obviating aerial transport. Nevertheless, the seasonal and diurnal distributions of conidia found were similar to those reported for other tropical regions of the world. Received: 13 August 1996 / Accepted: 4 December 1996     

Artificial neural network models of relationships between <Emphasis Type="Italic">Alternaria</Emphasis> spores and meteorological factors in Szczecin (Poland)

Alternaria is an airborne fungal spore type known to trigger respiratory allergy symptoms in sensitive patients. Aiming to reduce the risk for allergic individuals, we constructed predictive models for the fungal spore circulation in Szczecin, Poland. Monthly forecasting models were developed for the airborne spore concentrations of Alternaria, which is one of the most abundant fungal taxa in the area. Aerobiological sampling was conducted over 2004–2007, using a Lanzoni trap. Simultaneously, the following meteorological parameters were recorded: daily level of precipitation; maximum and average wind speed; relative humidity; and maximum, minimum, average, and dew point temperature. The original factors as well as with lags (up to 3 days) were used as the explaining variables. Due to non-linearity and non-normality of the data set, the modelling technique applied was the artificial neural network (ANN) method. The final model was a split model with classification (spore presence or absence) followed by regression for spore seasons and log(x+1) transformed Alternaria spore concentration. All variables except maximum wind speed and precipitation were important factors in the overall classification model. In the regression model for spore seasons, close relationships were noted between Alternaria spore concentration and average and maximum temperature (on the same day and 3 days previously), humidity (with lag 1) and maximum wind speed 2 days previously. The most important variable was humidity recorded on the same day. Our study illustrates a novel approach to modelling of time series with short spore seasons, and indicates that the ANN method provides the possibility of forecasting Alternaria spore concentration with high accuracy.