Pollen grains are one of the most important groups of atmospheric biological particles that cause allergic processes. Meteorological factors affect the occurrence of pollen allergen release in the air. In order to shed light on this phenomenon this study compares the ash pollen seasons in Bialystok, Bydgoszcz, Sosnowiec, Piotrkow Trybunalski, Opole, Olsztyn, Szczecin, Warsaw and Lublin in 2019. The investigations were carried out using the volumetric method (Hirst type pollen sampler). Seasonal Pollen Index (SPI) was estimated as the sum of daily average pollen concentrations in the given season. The ash pollination is mainly observed in April. Diagnosis of ash pollen allergy is made difficult due to an overlapping pollination period with Betulaceae and some cross-reactivity with allergens from Betulaceae. It is not clear whether ash pollen is a primary cause of sensitization or whether it is implicated through cross-sensitization to other pollens. In 2019 the pollen season of ash started first in Opole, on the March 9th. At the latest, a pollen season ended in Bialystok, after mid may. The differences of pollen seasons duration were very considerable, from 28 to 50 days. The highest airborne concentration of 190 pollen grains/m3 was noted in Lublin on the April 21st. The maximum values of seasonal pollen count in Polish cities occurred between April 4th and 22nd, most often between April 18th–22nd. The highest ash pollen allergen hazard occurred in 2019 in Lublin, Warsaw, Piotrkow Trybunalski and Bydgoszcz, and was at least three times higher than in other cities. The highest variability in the analysed seasons was found in the peak value and annual total.