Joint cooperation on environmental protection in the past three years between Beijing, Tianjin and Hebei province has resulted in significantly improved air quality in the region.

China has promoted the integrated development of the Beijing-Tianjin-Hebei region in recent years, relocating nonessential functions from Beijing and restructuring the economy in the region, with environmental protection, traffic management and industrial upgrading being prioritized.

In the past three years, the three local governments have expanded cooperation on information sharing, including holding joint emergency meetings, as well as standards drafting, policy-making and joint financing.

Yu Jianhua, chief engineer of the Beijing Environmental Protection Bureau, said the authorities of the three areas formed a mechanism in March 2015 to jointly cope with violations of environmental laws.

At the beginning of last year, Beijing, Tianjin and Hebei unified emergency response standards for severe air pollution.

In April, the three governments unified petroleum emission standards for vehicles.

"Beijing has invested in Hebei's environmental protection, helping to cut coal use," Yu said.

According to the bureau, Beijing has invested 962 million yuan ($139 million) in an air pollution control fund in Hebei in the past two years. Tianjin contributed 800 million yuan to the fund during the same period.

The results have been significant, with the industrial province of Hebei cutting coal use by 3.2 million metric tons in the past two years.

Beijing, Tianjin and Hebei have reduced coal consumption by 40.3 million tons in the past three years and cut iron production capacity by 40 million tons, which has contributed to the improved air quality.