Some people are allergic to pollen because their immune system reacts abnormally to what is otherwise a harmless substance. Pollen allergies, also known as hay fever or allergic rhinitis, occur when the body mistakes pollen grains for harmful invaders and initiates an immune response against them.

Here’s a simplified explanation of the process:

1. Entry of Pollen: When someone allergic to pollen inhales tiny pollen particles, these allergens enter their nasal passages and sinuses.
2. Immune System Response: The immune system identifies the pollen as foreign and produces antibodies called Immunoglobulin E (IgE) to neutralize the perceived threat.
3. Release of Histamine: The IgE antibodies attach themselves to mast cells found in the lining of the nose, eyes, throat, and lungs. When pollen comes into contact with these antibodies, the mast cells release chemicals, including histamine.
4. Symptoms: Histamine and other inflammatory chemicals cause the symptoms associated with pollen allergies, such as sneezing, runny nose, itchy eyes, congestion, and sometimes asthma attacks. These symptoms are the body’s attempts to expel the allergen and protect itself.
5. Genetic Predisposition: Individuals with a genetic predisposition are more likely to develop allergies. If a person’s parents have allergies, they are at a higher risk of developing allergies themselves.
6. Exposure and Sensitization: Continued exposure to pollen can sensitize a person who wasn’t previously allergic, leading to the development of an allergy over time.

Pollen allergies are particularly prevalent in the spring and fall when trees, grasses, and weeds release large amounts of pollen into the air. Different people can be allergic to different types of pollen, so the severity of their symptoms can vary throughout the year based on which plants are pollinating.