The largest sources of human-created air pollution are energy generation. And industries that use a great deal of energy sources. Depending on their sources and interactions with other components of the air, they can have different chemical compositions and health impacts. The majority of developing countries, where the most rapid urbanization and industrialization in the world is occurring. The growth of both industrialization and residential areas is unplanned ,unstructured and unzoned.
The result of such rapid and unplanned development is growing levels of air pollution, more pollution-related health problems. Urban growth is accompanied by increased traffic and energy consumption. Use of motor vehicles is growing rapidly in developing countrles.