Those chimneys erected in Shenyang Smelter used to be the pride of Shenyang, but now they are the main pollution resources of this city. Every year, they produce sulfur dioxide and lead dust each makes up of 42% and 98% of the total pollution. 10 years ago, National EPA ordered this smelter to treat its pollution, and gave it many financial aids. But this problem is still unsolved. In the middle of 60's, America did an investigation around several cities; it showed that the deeper the chrome of sulfur dioxide the lower the price of estate. So this smelter did a great harm to the economic and environment around. So this serious problem must be solved to improve the image of Shenyang.