China has ordered steel and aluminum producers in 28 cities to slash output during winter, outlined plans to curb coal use in the capital and required coal transport by rail in the north, as Beijing intensifies its war on smog, a policy document shows. The 26-page document dated Feb. 17 and seen by Reuters did not include some stringent steps proposed in a draft policy to slash fertilizer output and introduce a full ban on coal being handled at Tianjin, one of the country's busiest ports. The government has called on steel producers to halve output in four northern provinces - Hebei, Shanxi, Shandong, Henan - as well as Beijing and Tianjin, during the peak winter heating months around late November to late February. The size of the cuts will depend on the level of regions' emissions cuts.