TOPSHOTS Indian schoolchildren wearing facemasks pose for a photograph during before the start of an event to spread awareness of the problem of air pollution in New Delhi on June 4, 2015, on the eve of World Environment Day. The Indian government is under intense pressure to act after the World Health Organisation last year declared New Delhi the world's most polluted capital. At least 3,000 people die prematurely every year in the city because of air pollution, according to a joint study by Boston-based Health Effects Institute and Delhi's Energy Resources Institute. World Environment Day is marked anually on June 5. AFP PHOTO/MONEY SHARMA