GRASS POLLEN (POACEAE) IN THE AIR OF SOSNOWIEC (POLAND), 1997 – 2006

The article presents the analysis results of the grass pollen seasons from 1997 to 2006 in Sosnowiec. The research was carried out by means of the volumetric method with the use of a Burkard device. The duration of the pollen seasons was determined by means of the 98% method. The infl uence of meteorological conditions on the starting date and duration of the grass pollen seasons has been estimated in the article. The beginning of the pollen seasons was recorded between 23 April and 23 May. It has been demonstrated that the average duration of the pollen season amounted to 138 days. The period of maximum concentrations was recorded in June and the fi rst half of July. The highest daily concentration was found in 2000 (495 grains in m3) and the highest annual sums in 2002 and 2000. The daily concentration distribution curve has shown three peaks. The highest values were recorded from 7 am until 11 am, from 13 pm until 17 pm and from 19 pm until 21 pm. It has been found that there is a signifi cant infl uence of weather conditions (temperature, precipitation and relative humidity) on the beginning and duration of the pollen seasons and the period of maximum concentrations.


INTRODUCTION
Grasses are a natural component of fl ora.They grow almost everywhere: in forests, on meadows, sand dunes, steppes, in deserts, in the mountains, in lowlands in different climate zones.They are perennial or annual, wind-pollinated, herbaceous plants.Approximately 160 species of grasses can be found in Poland.Cultivated grasses, mainly corn, also belong to the grass family.Grass fl owering biology is characterized by great diversity both between species and within one species.The duration of fl owering depends on the diversity of this population and weather conditions.Particular species fl ower during the time of the day which is specifi c to them and in specifi c thermal and humidity conditions (B o c h n i a r z, 1960; R u t k o w s k a, 1970).The pollination season is long -it lasts from May to the end of September -because of a great number of grass species.
Grass pollen allergens are responsible for the most frequent causes of pollinosis in many European countries (S p i e k s m a, 1989; B e r g e r, 2003).In Europe, an allergy to grass pollen is found more often than to the pollen of other plants.It is also the main cause of pollinosis in Poland (L i g ę z i ń s k i and R a p i e j k o , 1994; Ś p i e w a k, 2001).Over 90% of the population suffers during grass fl owering (O b t u ł o w i c z et al. 1990).Disease symptoms caused by grass pollen allergens develop in some patients when a concentration value in a cubic metre of air exceeds 20 grains in m 3 , and in all of them when they are exposed to a concentration of over 50 grains in m 3 (R a p i e j k o et al. 2004a).These values are treated as medium and high, but very high concentrations when they exceed 100 grains in m -3 of air (R a p i e j k o, 2003).
The results of the ten-year research on grass pollen in Sosnowiec are presented in the article.When analysing them, particular attention was paid to the variability in pollen concentrations during grass vegetation and to the course of the pollen seasons depending on weather conditions in the years discussed.

MATERIALS AND METHODS
The aeropalynological study in Sosnowiec was carried out from 1997 to 2006 by means of the volumetric method with the use of a Burkard device.A trap site is located at a height of 20 metres on the University of Silesia premises in the district characterized by dispersed blocks of fl ats, near allotments at the junction of two arteries.The duration of the grass pollen seasons was determined by means of the 98% method (E m b e r l i n et al. 1993).Data from the Meteorological Observatory and the Environment Dynamics Laboratory in the Faculty of Earth Sciences at the University of Silesia were used to determine the relationships between the pollen seasons and meteorological conditions -average, minimum and maximum temperature of air, relative humidity and rainfall.The degree of correlation between meteorological parameters and grass concentrations was described by the Pearson's correlation.

RESULTS
Considerable variability in the course of the grass pollen seasons regarding the beginning and duration of the pollen season, maximum concentration values and the period of their occurrence was found during the tenyear pollen monitoring conducted in Sosnowiec.The concentration of wild grass and corn pollen was jointly monitored over all the years of study.With regard to corn, only rye pollen was found in small quantities.
Grass pollen in the air of Sosnowiec was noticed from late April to the end of September.The average duration of the pollen season over a period of ten years amounted to 138 days.The longest pollen seasons, which lasted 154 days, were recorded in 1998 and 2001, the shortest pollen season, which lasted 123 days, was noted in 2003 (Tab.1).
During the decade discussed, the grass pollen season was recorded earliest on 23 April in 1999 and 2000, and latest in 1997 -as late as 23 May.In 2005 and 2006, it was recorded in mid May and in the remaining years -in early May (Tab.1).The beginnings of the pollen seasons differed by one to thirty days.The weather conditions, particularly temperature, sunshine and relative humidity, infl uenced the beginning of the grass pollen season.A positive correlation was found with the average temperature of April and May and the maximum temperature of April.In 1999 and 2000, the high temperatures of April (14.8°C -20.3°C) and May (15.5°C -21.4°C) resulted in earlier vegetation of grass and the presence of pollen in the atmosphere (Fig. 1).The average temperatures of April and May in 1997 were 10°C and 13.7°C -the pollen season was recorded latest in the years discussed.
Over the period of ten years, the grass pollen concentration dynamics showed some differences (Figs 1-3).One can distinguish a few growth stages of the pollen concentration by the analysis of the course of grass pollination in particular years.In 1999In , 2000In and 2002, , the fi rst growth stage with a medium and high pollen concentration was recorded as early as the fi rst half of May.In the remaining years, it was recorded in the second half of May with the exception of 1998.The next distinct concentration increase was observed in June and July, when the highest concentrations during twenty-four hours were recorded.The maximum daily grass pollen concentrations were recorded in 1997in and 2000in -2003in between 5 and 15 June, in 1999in and 2004in -2006 in the fi rst half of July, and in 1998 not until late July (Figs 1-3).In the period of maximum grass pollination, there were days characterized by low pollen concentration values, which was caused by a few days' heavy rainfall.It brought about a halt or delay in grass fl owering by a few days.Since the middle of July, the grass pollen concentration gradually decreased, reaching medium and low values.The high pollen concentration lasted longest in 2005 -until 2 August -as well as in 1998, 2004 and 2006 until the end of July (Figs 1-3).The differences in the periods of maximum concentrations were caused by the weather conditions in the study years, particularly by rainfall, relative humidity and a temperature drop.l i n , 1991).There were differences between successive years with regard to the variation of the pollen concentration daily curve in Sosnowiec.A rapid increase in the pollen concentration was recorded from 7 am to 9 pm.The daily curves in Sosnowiec differ with regard to the occurrence of maximum concentrations when compared with Poznań (S t a c h, 1997; G o l i ń s k a, 2006), Rabka (K a s p r z y k et al. 2001), Gdańsk (L a t a ł o w a and G ó r a , 1995) and Lublin (P i o t r o w s k a, 2005).However, one can notice that one peak of pollination occurs in the morning and the second peak in the afternoon.The weather conditions (temperature, precipitation, humidity) and also the local factors (urbanization) signifi cantly infl uence these regional differences.
It has been found that the average and maximum temperature and relative humidity have a considerable impact on the beginning and duration of the pollen season and on the level of maximum daily concentrations.The high temperatures of April and May speed up the grass pollen season beginning and the period of the occurrence of maximum concentrations.

CONCLUSION
1.The average duration of the grass pollen season over a period of ten years amounted to 138 days.During the decade discussed, the grass pollen season was noticed earliest on 23 April in 1999 and 2000, and latest on 23 May 1997.
2. The weather conditions, particularly temperature, sunshine and relative humidity infl uenced the beginning of the grass pollen season.A positive correlation was found with the average temperature of April and May and the maximum temperature of April.
3. The period of the maximum concentrations was recorded in June and the fi rst half of July.