To ensure blue skies during September's G20 Summit, host city Hangzhou, Zhejiang province, and surrounding regions recently released plans to restrict air pollution.

The upper limit of PM2.5 pollutants in Hangzhou was set at 35 micrograms per cubic meter during the summit. G20 presidents and senior officials representing 90 percent of the world's GDP and two-thirds of the world's population, will participate.

Hangzhou's daily average concentration of PM2.5 was 57 micrograms per cubic meter in 2015.

PM2.5 refers to airborne particles 2.5 microns or less that affect health.

The city government's plan includes the closure of several chemical enterprises. It ordered that by mid-August, Hangzhou Bald Silicon, which produces more than 100 silicone products, must be closed and relocated.

Manufacturing of chemical compounds by Hanghua Ink and Paint are to be closed down by the end of this month, and the production of viscose, an artificial fiber, by Fulida Group was to be suspended before mid-August.

By the end of this month, buses using diesel fuel and whose exhaust emissions fail to meet the latest national standards will be taken off the roads in six central districts.

Other places in the Yangtze River Delta have also released plans to ensure G20 Blue.

The environmental protection authority in Shanghai, which borders on Zhejiang, ordered 255 enterprises in petrochemicals, steel and cement production to limit production from Aug 24 to Sept 6.

During that period, the power plant at Baoshan Iron and Steel, China's largest steel manufacturer, will be shut down, and production at Sinopec Shanghai Petrochemical, one of the country's largest petrochemical enterprises, will be cut by at least 50 percent.

An information officer at Baoshan said the company will follow the restriction order strictly.

Some other cities, including Huangshan and Anqing, Anhui province, and Yiwu, Zhejiang province, also plan to support G20 Blue.

During the summit, environmental protection inspectors will patrol key transportation areas, such as the airport, railway station and highways to catch emission violators and to prevent the burning of crop waste and garbage.

zhouwenting@chinadaily.com.cn