Environmental authorities publish findings on the leading air pollution sources in China's major cities;Beijing introduces stricter rules to tackle smog;Nanjing becomes the first city in the country to adjust the monthly franchise fees for taxi drivers;Hong Kong becomes the third city in the world to host a "Raising the Bar" event.Elsewhere in Hong Kong a number of modern Chinese paintings are being displayed and are set to go under the hammer soon;And last but not lease, we will hear the story of a doctor who was sent to Sierra Leone to provide medical aid to African people.