Smog billows from chimneys and cooling towers of a steel plant during hazy weather in Taiyuan, Shanxi province, China, December 28, 2016. REUTERS/Stringer

SHANGHAI (Reuters) - One of China’s top coal-producing provinces has vowed to slash its level of fine particle pollution by one-fifth by 2020, the official Xinhua news agency reported on Saturday, citing the provincial government.

China has adopted various measures from policing barbeques to halting industrial production in efforts to ease the yearly winter haze that hit the country earlier this month leaving cities veiled in foul-smelling smog.

China’s northern Shanxi province aims to increase the proportion of days per year with good air quality to 75.4 percent, the agency said.

The move comes after concentrations of PM2.5, fine particulate matter, in a major northern Chinese city exceeded a World Health Organisation guideline by 100 times in December.

The province will create a pollutant discharge license system covering all polluting enterprises, while industrial capacity expansion will be restricted and no new coal, steel, cement or plate glass projects will be approved, it added.

By the end of 2017 all coal-fired plants of 300,000 KW and above will be upgraded to produce fewer emissions, Xinhua said.

But under its five-year plan for the coal sector, the state planner said it was targetting national coal output of 3.9 billion tonnes in 2020, up from 3.75 billion tonnes in 2015, even as it attempts to tackle pollution.