Hello . It appears to be allergic symptom. Avoidance is the best therapy. Better consult nearby ent for further evaluation with CT scan if needed to rule out sinusitis too.

You seem to be having mild dust / pollution allergy which is leading to excessive formation of secretions in your nose which come into your throat.. Avoidance is the best way to reduce your symptoms but as you said it can't always be done. Steam inhalation twice a day will be helpful in clearing the secretions.. And also the dust from your nose. Usage of medicines will be only temporary relief.. Breathing exercises and steam will help you.. If there is nasal obstruction or blockage then sinusitis will have to be ruled out L

Consult online with pic of throat with proper history and video consultation for better understanding of problem