A documentary film investigating China’s poor air quality was pulled from major Chinese online video sites on Friday by order of the government after it drew millions of views, the Wall Street Journal reported.

“Under the Dome” was withdrawn from Internet services including Youku Tudou Inc. and Tencent Holdings Ltd.’s v.qq.com, the Journal said, citing unidentified people familiar with the government directive. Former China Central Television reporter Chai Jing released the film online on Feb. 28.

Chinese propaganda officials also requested that publications drop future coverage of the film and play down any existing stories online, the Journal said, citing several unidentified journalists.

The documentary, which cites weak enforcement of environmental laws and poor fuel standards among the causes of smog, appeared shortly before the annual meeting of China’s National People’s Congress, which started in Beijing Thursday. Legislators discuss and endorse government policies on issues ranging from economic growth to military spending and pollution.

Chinese President Xi Jinping said the government will punish environmental violators with an “iron hand,” The official Xinhua News Agency reported on Friday. The nation should take into consideration environmental costs and pollution, said Shandong province Governor Guo Shuqing said in an interview in Beijing this week. 

Two phone calls by Bloomberg to the State Administration of Press, Publication, Radio, Film and Television, the media regulator, weren’t answered outside of business hours in China.

Air pollution has become a focus of public discourse in China in recent years as thick smog has blanketed large swathes of the country. Chai says in the documentary she became afraid of pollution for the first time after her baby daughter was given an operation soon after birth to remove a benign tumor. She displays pollution charts and footage of doctors removing blackened lymph nodes from the lungs of a patient who didn’t smoke but was diagnosed with early-stage lung cancer.

“This is a personal grievance between me and the smog,” Chai said in the film.

China’s new environment minister, Chen Jining, said this week that he had watched the documentary and sent Chai a text message to express his gratitude as she “raised public attention on the environment,” according to Xinhua. Ninety percent of the 161 cities whose air quality was monitored in 2014 failed to meet official standards, according to a report by China’s National Bureau of Statistics last week.

The dominance of PetroChina Co., the country’s biggest oil and natural gas producer, and China Petroleum & Chemical Corp., Asia’s biggest refiner, was cited by the documentary as a key reason the country has been slow to produce more clean energy. Calls by Bloomberg to the two companies weren’t answered after business hours Friday.

Last year, Beijing pledged 760 billion yuan ($121 billion) to reduce pollutants, and the city’s mayor vowed to clean up the air by 2017, according to Oriental Outlook, a magazine run by Xinhua. Neighboring Hebei province has scaled back its heavily polluting steel and coal industries, according to state media reports. (Bloomberg)