Define Perennial allergy.

Perennial allergy:

1. Perennial allergies (year-round) occur from indoor exposure to airborne substances (such as house dust) that are present throughout the year.
2. People who suffer from perennial allergic rhinitis experience symptoms year-round.
3. Symptoms like nose congestion, itchiness, and sometimes runny, and the mouth and itchy throat are seen in perennial allergy.