China's environment ministry has vowed to ''harshly punish'' factories and power plants that contributed to a hazardous smog which enveloped much of Northern China, official state media report.
Investigations had found that some thermal power plants, cement and steel makers in the northern province of Hebei had failed to halt or curtail production during severely smoggy days despite government orders, state news agency Xinhua quoted the Ministry of Environmental Protection as saying.
Northern China had in recent days been suffering its worst air pollution crisis in months, leading to public displays of dissatisfaction, including people placing anti-pollution face masks on statues.
In Beijing, which was shrouded in stinking smog for more than a week, authorities raised the pollution alert to the second-highest "orange" danger level for the first time on Friday after drawing public ire for its ineffective response.
The noxious haze, which can cause lung cancer, abated on Wednesday evening, just before China's leaders gather for next week's National People's Congress Meeting.
China will introduce measures to combat the smog, including constructing 12 electricity ''channels'' to bring in energy from farther away, Xinhua also reported on Wednesday, to reduce the reliance on pollution-creating power plants in northern and eastern China.
Authorities have introduced countless orders and policies and made innumerable vows to clean up the environment but the problem only seems to get worse.
The government has invested in projects and empowered courts to mete out stiff penalties but enforcement has been patchy at the local level, where authorities often depend on the taxes paid by the polluting industries.
Hebei, a major industrial region which surrounds Beijing, is home to some of the most polluted cities in China. Shijiazhuang routinely recorded "beyond index" measurements of particulate matter in early 2013.
The China Academy of Sciences identified the province as a major source of noxious smog that hung over Beijing a year ago.
The government said in an action plan for Hebei in September that it would ban new projects in certain industries, close outdated steel and cement facilities and slash coal use.
The province has promised to cut total steel capacity by 86 million tonnes, about 40 per cent of last year's production, by 2020. Official data suggests that is starting to happen.