beijing beijing city authorities take website policy document put days ago look help improve city notorious air quality ban construction winter months unclear move mean prohibition long place official beijing municipal commission house urban-rural development give name yu say document pull website due misunderstand rule media report decline give detail statement date sept. 15 post commission website last friday long available wednesday clear withdraw plan construction road water project well demolition house would ban nov. 15 march 15 within city six major district surround suburbs part dust control measure government often instruct construction sit northern cities close bouts heavy smog winter households crank heat draw power grid mainly fuel coal provincial authorities rush enforce central government ambitious target prevent toxic air upcoming cold months ramp years-long war smog possible pull construction rule underscore complexity implement step among stringent measure order heavy industry steel mill curb output much 50 percent cold months recent check factories across north force many close curb operations roil supply critical raw materials like coke coal send price base metal soar beijing government pull winter construction ban website