Noor, ask your friend to go to his son's paediatrician and tell him the possibility of moving here. Once environmental conditions are known by the child's doctor there would be a good approach as on how to treat the kid, or which specialist to see the kid upon arrival into Qatar.

Regards!!

PS: asking for advice on medical conditions in a Public Forum could lead you to misunderstanding or to several different points of views making it more difficult to take a decision/action. Always go to your doctor for specialized advice.