Authorities in a major Chinese city used water cannons to increase humidity and reduce pollution as much of the country has fallen under hazardous smog clouds.

The anti-smog cannon, driven onto the streets of Hunan provincial capital Changsha, blasted small drops of water into the air on Tuesday. Nine tonnes of water was used over an hour and a half, local media Changsha Evening News reported.

Photo: Sina News.

China’s Central Meteorological Administration said on Wednesday that heavy smog is expected to cover a large part of northern China in the next 24 hours before gradually dispersing on Thursday. Visibility in some areas will be reduced to below 200 metres.

Photo: Sina News.

The low visibility caused a 33-vehicle pile-up on a highway in Shanxi earlier this week, killing six and injuring four others.

Beijing issued its first ever red smog alert on Monday, the highest warning level. Schools were suspended and special traffic controls implemented.

A 33-car pile-up on a Shanxi highway. Photo: Weibo.

Changsha was not the first city to use water cannons to fight air pollution.

Huge humidifiers were also spotted in Jinan, capital city of Shandong province, earlier this week. Authorities said blasting mist into the air can help bring down dust and increase air quality.

However, some were not convinced. Netizens questioned how useful this method was, while many said it was not a long-term solution.