China's top environmental watchdog said on Saturday it will impose tough penalties on people who manipulate or falsify environmental monitoring data, with criminal liability in severe cases.

The Ministry of Ecology and Environment has a zero-tolerance policy for such deceptive practices and will strengthen inspections and punishment for violators, said a statement on its website.

The statement came after a court in Jinzhong, Shanxi province, sentenced five people on May 30 - including the former head of environmental protection in Linfen, Shanxi - to prison sentences of six months to two years for tampering with air quality monitoring equipment and falsifying data.

Another 11 people received four-to six-month terms in a house of detention. According to the verdict statement, they had been found guilty of "damaging the computer information system".

In March, China National Environmental Monitoring Center notified the ministry of abnormal air quality data from Linfen. The ministry sent an inspection team and found that the monitoring systems at six of the city's stations had been tampered with.

A police investigation determined that air quality monitors had been tampered with more than 100 times in a one-year period beginning in April 2017.

In March 2017, Zhang Wenqing, former head of Linfen's environmental protection bureau, ordered an official to find ways to "beautify" air quality data in the city, which was in the spotlight due to its frequent alarmingly high concentrations of sulfur dioxide. In January 2017, the level of sulfur dioxide rose above 1,000 micrograms per cubic meter on four occasions.

The perpetrators were promised 3,000 yuan ($460) per month and were given masks, hats, helmets and gloves to hide their identity.

The Linfen government said in a statement on Sunday it was deeply sorry for the lack of supervision on officials and would take stricter actions to ensure the city's air quality monitoring stations function normally.

Warning signs would be placed around the stations and only staff members would be allowed within 20 meters of the stations, it said.

Ma Jun, director of the Institute of Public and Environmental Affairs, said the severity of data falsification in Linfen is rare and shows that the local government still attaches more importance to economic development and political achievement than environmental protection.

A stricter assessment system puts greater pressure on local environmental protection departments and sometimes touches the interests of the leaders, which is the main reason for the illegal behavior, Ma said.

It is important to involve the public and research institutes in the supervision so that people can tip off authorities in the event of illegal behavior, he said.

In June 2017, a local court in Xi'an, Shaanxi province, sentenced seven people, including the heads of two environmental protection bureaus in districts of Xi'an, to jail terms of over one year for falsifying air quality monitoring data.

They were found guilty of interfering with the data collection of the air quality monitoring system, plugging the sampling instrument with cotton to lower the pollution data. Falsifying environmental data to avoid pollution regulations has been punished as a criminal offense since January 2017, under judicial interpretations on environmental crimes formed by the Supreme People's Court and Supreme People's Procuratorate, the nation's top court and prosecuting office.

Previously, such offenders usually received administrative penalties.

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