Third, the government should actively consider economic measures to cut down on consumption of resources as well as reduce pollution. These could include a natural resource tax on coal and other resources, and a gradual increase in tax rates. It also needs to pilot emission taxes on major pollutants such as sulfur dioxide and nitrogen oxide in selected areas.

In Beijing, higher fuel tax rates would help address the proliferation of motor vehicles and reliance on oil imports. Cities with seriously clogged roads can introduce "congestion taxes" to reduce traffic jams and cut vehicle emissions at the same time. It is also important to adjust the emission tax rates to provide proper incentives for enterprises to abate pollution.

Fourth, for environmental authorities to grant emission permits, industry should be required to adopt the best available clean technology. It is also important to ensure that factories actually use such technology appropriately. Improvements in air quality are critically dependent on proper supervision and assurance that emitters comply with regulatory requirements. The current permit system in China lacks a firm legal basis as well as enforceable rules. It also lacks requirements for data and information to be provided by enterprises, which are essential for supervision and enforcement.

And fifth, the new Environmental Protection Law should be strictly and effectively enforced. Public access to the legal system on environmental issues would be enhanced if environmental courts were strengthened and the legal rights of citizens clarified. There should also be appropriate penalties and sanctions to give enterprises incentive to comply with the law. And the local environmental protection bureaus should be empowered with clear authority to impose penalties.

The ADB loan to Hebei made policymakers in province commit to air quality control, while enhancing the provincial environmental protection bureau's enforcement capacity.

Recent blue skies over Beijing bode well for China's journey toward an "ecological civilization", a stated ambition of the 13th Five-Year Plan (2016-20). China, and the wider international community, will breathe easier if there is tangible progress.

The author is director general for East Asia at the Asian Development Bank.