Allergens are microscopic invisible particles responsible for your allergy symptoms.
Air bound allergens are called aeroallergens. It can be
1. perennial,
2. seasonal or
3. perennial with seasonal exacerbations.
Depending on the allergen to which you are allergic to, symptoms vary accordingly.
Fungal spores or molds are perennial, while pollens are mostly seasonal. Dust mites vary depending on place and climate.
Few insects like mosquitoes and cockroaches can act like aeroallergens too.
Consult an allergist to get your sensitization checked and discuss to find out the allergen responsible.