The grass pollen season dynamics in relation to the meteorological conditions in Cracow, southern Poland, 1991-2008

The aim of the study was to analyse the grass pollen season dynamics in Cracow in 1991-2008 and to find the relationship between the meteorological conditions and season parameters. The pollen season started on average on the 138th day of the year (±10 days) and ended on the 211th day (±10 days). The median of the SPI value (calculated by the 95/90% method) was 2041, peak concentration – 111 pgm-3 (achieved on average on the 34th day of the season/173th day of the year). The average temperature in April-May showed the greatest effect on the start and end of the season (negative correlation). Tmean of the third decade of June influenced the season end (rs negative). Tmean of April-May correlated negatively with the time of peak concentration. Rainfall in January and April influenced the season start. Relative sunshine in March-April was related to the season start, in the third decade of June it was related to the season end (negative correlation), in March-April it influenced the time of peak concentration (positive correlation), while in January-March the peak concentration (positively). Cloudiness in February-May and also in the third decade of June had an impact on the season end and time of peak concentration (positive correlation). Humidity in February influenced the season start (negatively). The SPI value was influenced by relative sunshine (positively) in February-May, by humidity in April, and cloudiness in February-March (negatively).