March is a period of intense hazel pollen dispersal in Poland. Although this shrub begins to release pollen as early as January, it is at the turn of February and March that pollen concentrations in the air often reach high levels. For many allergy sufferers, this marks the start of the season of allergy symptoms linked to tree pollen. The hazel is a wind-pollinated plant, which is why its pollen can be carried over long distances.