Xiongan New Area in Hebei province has shut down thousands of polluting companies to curb pollution since it was announced in April.

More than 7,200 companies that discharge heavy pollution were investigated and nearly 4,000 of them were closed, according to the area's official account on WeChat, the country's leading social platform.

Also, about 100 people involved were arrested, and detained for questioning about actions that might have contaminated the environment.

The strong reaction by the authorities illustrates the determination of the area's leaders to tackle environmental problems.

Xiongan New Area, established as part of the measures to advance the coordinated development of the Beijing-Tianjin-Hebei region, is required to put environmental safety first and adhere to green development.

When it was announced four months ago, one of the goals laid out was to create a "naturally scenic city with blue skies, fresh air and clean water".

Located about 100 km southwest of downtown Beijing, Xiongan spans Hebei's Xiongxian, Rongcheng, and Anxin counties.

It also covers a major wetland in northern China - Baiyangdian Lake, which covers 366 square kilometers and is believed to be a key in improving the area's overall environment.

But in the area is Baoding in Hebei province, usually one of the 10 cities with the worst air quality in the country. Baiyangdian's environment has been damaged for years by pollution resulting from fisheries and industrial waste water.

To control the pollution, the three counties have taken a series of measures.

Hebei Party chief Zhao Kezhi said the area must accelerate the restoration of Baiyangdian and must plant trees on a larger scale in the goal to increase the area's forest coverage rate.