Hangzhou, the capital city of Zhejiang Province, plans to shut down more than 250 high-polluting factories and relocate 12 others in order to improve its air quality.

A city air pollution management plan released on Monday orders that 255 high-polluting factories -- including Hangzhou Refinery, which is affiliated with China Petrochemical -- must shut down by the end of the year. The closings will begin on July 19.

Other essential but polluting companies, including Hangzhou Iron & Steel Group Co, will be relocated to a remote, less-populated area.

The city also has vowed that no such new factories will be approved in the future, and says that new construction projects should use clean energy, such as electricity and natural gas.

The city also plans to replace 60 percent of its buses with clean-energy-powered buses this year.