Dear Fahim, Welcome to Healthcaremagic!
Premature greying of hair [canities] is a common condition. Contrary to usual belief, it is not due to pollution or dust; rather genetic factors play major role. In early stages, it is treatable. You may take Tab. Calcium Pantothenate
100 mg once a day daily for 6 months & let me know.
Also, take nutritious diet & keep your hair clean by shampooing 2-3 times every week. Good luck.