Beijing authorities are investigating photos circulating online showing a fog cannon blasting clean air towards an air quality monitor, as the city recorded “hazardous” levels of pollution on Thursday.

Users of Chinese social media Weibo said that the photos were taken at a monitoring station near the Chinese capital’s Olympic Sports Centre.

Pollution Air Quality Index AQI
A fog cannon blasting clean air at Beijing’s Olympic Centre. Photo: Weibo.

“The municipal environmental protection bureau has noticed online media reporting of a ‘fog cannon’ operating around an environmental monitoring station,” said the Beijing government in a Friday statement.

“It has always been the municipal environmental protection bureau’s stance to safeguard the accuracy, reliability, objectiveness and truthfulness of environmental monitoring statistics, and to have ‘zero tolerance’ for any actions to affect environmental monitoring statistics.”

The bureau said it would investigate and take action in accordance with the Ministry of Environmental Protection’s guidelines on the falsification of environmental statistics.

See also: Smog in Beijing off the charts as sandstorm engulfs capital

Weibo users reacted furiously to the suspected falsification of data. “Is there any point in this falsification? Wouldn’t it be better to build a sealed glass house and treat the air inside so the Air Quality Index (AQI)  becomes zero?” asked one commenter.

An AQI of over 300 is considered “hazardous”.

Air Pollution Air Quality Index AQI
A fog cannon blasting clean air at Beijing’s Olympic Centre. Photo: Weibo.

It is unclear whether the fog cannon had any effect on lowering the recorded pollution levels at the Olympic Centre. Taking data from official sources, the AQICN non-profit group recorded a maximum AQI of 550 at the same location on Thursday.

However, the nearby city of Langfang recorded an AQI of over 999 – off the charts.

Elson Tong is a graduate of international relations and former investigations consultant. He has also written for Stand News.