This undated photo shows the surroundings of Yuquan Mountain Forest Park. [Photo provided to chinadaily.com.cn]

At that time, local people dared not go out in white shirts, "because they would get dirty in less than half a day from the soot in the air and on the ground," explained Pei Weiwei, a 46-year-old resident near the mountain.

To Zhang's delight, local people's unpleasant memories have faded into history.

"We've completed 70 percent of our goal, treated 190 abandoned mines and cleared five of the seven landfill sites," Zhang said.

The past decade has seen the once-derelict mountain without electricity, water or roads growing into a green expanse covered by about 5.5 million bamboo, cypress, cherry and plum trees, and equipped with 105 kilometers of meandering road.