An aerial view of Taiyuan city, capital of North China's Shanxi province.

It has been 30 years since I arrived in Taiyuan to study at Shanxi University and in that time I have witnessed many changes.

During the 1990s I had just started work when Taiyuan began massive urban infrastructure construction. Within a few years, the dusty paths in the fields had expanded into wide and smooth asphalt roads. Skyscrapers rose side by side.

However, pollution was very serious. As an energy and heavy chemical Industry base, there were a good many steel and iron factories, power, chemical, fertilizer and heavy machinery plants around the city, all highly polluting.

The black and yellow smog from factory chimneys made the blue sky dark, as though naughty children had colored it with bold, black ink. At that time, if people were sent to Taiyuan on business, some might have wondered where it was, others may have imagined a picture of coal everywhere.

Time flies. Taiyuan has become cleaner and more beautiful. The large State-owned enterprises, such as Taiyuan Iron and Steel and Shanxi Coking Coal Group have implemented a policy of energy saving and emission reduction to curb environmental pollution. Highly polluting enterprises, such as Taiyuan Chemical Industry Group, have moved away. The chimneys spewing out black smog have been pulled down. People can see the blue sky and clear water and enjoy the singing of birds and fragrance of flowers again. So many changes have taken place in this once seriously polluted city that it is now renowned as "Fairview Taiyuan City".

Taiyuan city residents perform a sword dance in a park.