China's CCTV culture suffers as record high pollution and smog levels render country's 20 million surveillance cameras effectively useless

Experts claim that in many Chinese cities, pollution particles are so dense and compressed that they block light almost as effectively as a brick wall

Alongside countries like Britain and the United States, China has one of the most pervasive citizen surveillance operations in the world.

As well as some of the strictest internet access controls by any government on earth, the country also boasts an expensive and sophisticated CCTV network – a constant eye on the streets, searching for anything that could suggest criminal activity or a looming terror attack.

Until recently that is.

Smog is now such a problem in China’s cities that it’s 20 million surveillance cameras can no longer see through the thick layers of pollution that choke the streets on an almost daily basis.

Visibility in the city of Harbin fell to less than three metres on a particularly smoggy day last month and there are now fears that terrorists take advantage of the increasingly frequent haze to carry out attacks and flee unseen.

Speaking to the South China Morning Post today, Kong Zilong, an expert in video surveillance technology, said there are currently no cameras in existence that are able to cope with the pollution levels China is repeatedly experiencing.

Existing technology, such as the infrared cameras used by firefighters as they move through smoke-filled buildings, can help see through smog at a certain density, but when it reaches the concentration found on some Chinese streets, even that is shown to be useless.

Experts claim that in many Chinese cities, pollution particles are so compressed that they block light almost as effectively as a brick wall.

Mr Kong said: “According to our experience, as the visibility drops below three metres, even the best camera cannot see beyond a dozen metres”.

As one might expect, the Chinese government is taking this perceived threat to national security very seriously, commissioning groups of scientists to focus on finding a solution to this most cloudy of problems.

For the time being, China may be forced to use expensive and potentially health-harming military technology to ensure the peace is kept in some cities.

Professor Zhang Li of Tsinghua University says: “On the smoggiest days, we may need to use radar to ensure security in some sensitive areas.”

Professor Zhang concedes that such drastic methods would have to be temporary however, as the levels of radiation the public would be exposed to could have long-term health consequences.