Why do Indians suffer from vitamin D deficiency despite plenty of sunlight?

Despite living in tropical climate, many Indians suffer from lack of vitamin D. "Most people in urban areas spend...majority...time indoors," explained Dr Minesh Mehta, Consultant Emergency Medicine. This means less direct sunlight exposure. Cultural practices, like wearing clothes that cover most of the body, further limit skin exposure to the sun. High levels of dust, smog also block UVB rays.