SHANGHAI China's courts will widen the range of offences that constitute "environmental crimes" to make it easier to take legal action against polluters, a senior judiciary official told a news briefing on Monday.
The new rules could allow prosecutors to take on persistent offenders in northern China's Hebei province, which was engulfed in heavy smog last week despite being on the front line of China's nearly three-year "war on pollution".
Yan Maokun, head of a research office at the Supreme People's Court, told reporters authorities had struggled to gather evidence required to prosecute, according to a transcript of a briefing published on China's official court website (www.chinacourt.org).
"Air pollution is different from water pollution or soil pollution, and it is extremely difficult to get evidence for air pollution crimes because after the pollution is emitted it undergoes a large degree of dispersal, and is very quickly diluted," Yan said.
Prosecutors would focus on specific offences such as tampering with sensor equipment or providing false emissions data, and firms found guilty would be punished regardless of the amount of pollution involved, he said.
"It doesn't matter how much you emit because in fact that is very hard to detect, but if you have distorted or fabricated data or interfered with the operation of equipment, this ... will constitute an environmental crime," Yan said.
Public anger is mounting in China about pollution, and what many see as government talk, but little action, to end it. Worry about pollution has on occasion sparked protests.
Eight cities in Hebei launched "red alerts" last week in response to the smog, which reached record levels at some monitoring stations.
Hebei came under fire from the Ministry of Environmental Protection, and a number of its steel firms were singled out for failing to suspend operations.
Governor Zhang Qingwei said in the province's first official response that the province would learn lessons and step up its efforts.
"We need to seriously study and analyze our responses, sum up our experiences, and find problems and deficiencies in order to draw up more focused measures," Zhang was quoted as saying on an official website (www.hebei.gov.cn).
Experts say enforcement is lax amid concern about the impact on economic growth and jobs in Hebei, which surrounds Beijing and was home to seven of China's 10 smoggiest cities last year.
In the provincial capital of Shijiazhuang, average concentrations of small breathable particles known as PM2.5 were higher than 500 micrograms per cubic meter for three consecutive days last week - 50 times higher than World Health Organization recommendations.
In comments published on Monday, Zhang said better "top-level planning" was needed as Hebei sought to adjust its industrial and energy structures.
Hebei would also draw up more detailed plans to deal with issues like the direct combustion of coal, the provincial government said on its website (www.hebei.gov.cn).
The province aimed to cut PM2.5 concentrations to an average of about 67 micrograms per cubic meter this year, down from 77 in 2015, but officials have warned that targets will be difficult to reach.
According to a separate notice, officials said on Sunday that despite the recent smog, caused in part by "the most unfavorable weather conditions since 1998", Hebei was on course to meet its goals, with emissions in Shijiazhuang set to drop about 12 percent this year.
Hebei has declared 2017 a "year of transformation and upgrading", it said on Saturday.
(Reporting by David Stanway; Editing by Nick Macfie, Robert Birsel)