Before my father moved to Beijing for work in the early 1980s, he lived in a cave house on a barren mountain on the Loess Plateau in Shanxi, the province to the east of Shaanxi, bordering the Yellow River.

Recalling his childhood, he told me that his shirts were often dirty because of the high number of windy and dusty days, and said it was hard to find drinking water due to droughts and soil erosion.

He said such poor natural conditions prompted him to leave his home village and find a better place to settle down.

On several occasions in the 1990s, I accompanied him when he returned to his hometown to visit my grandparents.

The things that most impressed me were the headscarf my grandmother wore to keep her hair in place during sandstorms and the winding, uneven roads in the bare mountains that led to the village.

So, when I prepared for a business trip to Yan'an, a plateau city in Shaanxi, last month, I packed a scarf in my bag to keep out the wind and dust.

To my surprise, the air in Yan'an, located in northern Shaanxi and often called "the land of yellow earth", was clean, and its mountainous areas were almost all covered with trees.

When I wore a white shirt to visit high places and conduct interviews all day long, it didn't get dirty.

The improvement in living conditions is the result of a policy of returning farmland to forests that started in the city in 1998.

After many trees were planted in the following two decades, Yan'an's dominant color turned from yellow to green, with cleaner air and purer drinking water.

My interviewees told me that some other cities along the Yellow River in Shaanxi and Shanxi have also benefited from environmental conservation, thanks to the "green revolution" and the government's constant efforts in environmental and ecological protection in recent years.

As I stood with some villagers on a hillside in Yan'an's Yichuan county and looked at the greenery and flat, relaid roads, I knew that my grandmother's headscarf and my father's dirty shirts and dusty childhood were now part of the plateau's history.