Why do people have seasonal allergy?

Seasonal allergy can be defined as a reaction to some of the trigger that are present during particular part of the year which can be fall or spring. This allergy can be due to pollen grains, grasses, trees or weeds. Pollens are tiny particles that are very light in weight and are released from the plants or flowers and are carried from one location to other by the wind. When the pollen grains are present in the atmosphere, it can enter in the nose, lungs or skin of the person giving rise to allergic reaction. The main cause for seasonal allergies is the pollen which is spread by the winds because they can travel very long distance and their amount in the air can vary from one day to other. The other cause of seasonal allergy is the pollen from the tress such as oak, birch, ash and olive. Grass pollen occurs as a cause of late spring or may be the early summer and it can give rise to allergy when a person is moving in the lawn or is lying down on the grass. Grass contact can also lead to development of itching as well as hives in the people who are allergic to grass pollen.