Humans are allergic to pollen because their immune system mistakenly identifies pollen as a harmful substance. This misjudgment causes the immune system to react aggressively by producing antibodies, which then trigger the release of chemicals like histamine. These chemicals lead to the symptoms of allergies, such as sneezing, itching, and swelling. The allergy occurs because the immune system treats the harmless pollen protein as a threat, even though pollen itself is not dangerous.
The underlying reasons for why this misjudgment happens include genetic tendencies and environmental factors. For example, frequent exposure to pollen from a young age can lead to sensitization. Additionally, some theories like the "hygiene hypothesis" suggest that reduced exposure to bacteria and viruses in early childhood due to modern hygiene practices makes the immune system more prone to overreacting to harmless substances like pollen.
Pollen allergies are a form of seasonal allergic rhinitis and are caused by pollen from trees, grasses, and weeds, which are carried by wind or insects. The immune system's reaction to these pollen grains releases histamine and other chemicals that produce allergy symptoms.
