Beijing has been intermittently blanketed in thick smog since mid-December, and the latest measure officials are taking to clean up the air is a police squad set up to crack down on illegal incineration of rubbish and use of barbeques including wood burners.

The squad was announced by Beijing's acting mayor, Cai Qi, at a meeting on 7 January, among other measures such as shutting down the worst polluting factories and cutting coal use by 30% by the end of 2017.

In recent weeks more than 20 cities have been on red alert, the highest warning level for air pollution in China, which can lead to school closures, flight cancellations and shutting down busy roads.

What are the health risks of smog?

Some of the most dangerous components of smog are tiny particles of dust and soot, which cause damage to airways and lungs. These particles have been linked to lung cancer in China and they exacerbate respiratory conditions such as asthma.

Nitrogen oxides, also known as NOx gases, are another component of smog that cause inflammation of the airways. NOx gases also react with oxygen to form ozone, which is another irritant gas.

Outdoor air pollution in China is estimated to cause 1 million premature deaths a year, according to a 2016 report by the International Energy Agency. Exposure to air pollution knocks more than 2 years off average life expectancy in China, according to the report.

Beijing smog
Air pollution in China reduces life expectancy by 2 years. The recent and ongoing bout of toxic smog in the city is prompting officials to create an environmental police squad to enforce regulationsLWYang / Flickr

Why is the smog so bad in Beijing?

Weather, geography and the industrial activity of Beijing collide to make the city a particularly bad place for smog, James Lee, an atmospheric chemist at the University of York, told IBTimes UK.

The city sits in a large bowl surrounded by hills on each side. When there is little wind, the pollution settles in the bowl and there is not much that can be done to shift it.

"You get these periods when it's very still and there's no wind, so the smog just builds up and up over three or four days," Lee said. "That's just due to where it is geographically, they can't do anything about it.

"And then it does clear out, when a different kind of weather comes in and blows it all away."

Beijing smog
Smog causes a range of health problems, such as worsening respiratory conditions, and has also been linked to lung cancerLWYang / Flickr

The main sources of the smog in Beijing – especially particulates and NOx pollution – are thought to be large coal-burning factories, says Lee, who is working on a large UK and Chinese-funded project on Beijing's air pollution to identify the main causes of the smog and devise strategies to reduce it.

Will a smog squad do any good?

"It's really good to see they're looking at these unconventional ways of doing things," said Lee.

"Having this police force is certainly an interesting idea. Whether it's effective or not remains to be seen."

As the main sources of smog are large factories, it's not clear whether targeting the activity of individuals – such as the use of barbeques – will have any effect on the air pollution problem.

However, there is certainly a problem with enforcing existing environmental regulations on an organisational level in Beijing. Inspection teams have found evidence of factories and companies breaking a ban on production while under pollution red alert, Associated Press reported.

Beijing smog
The main causes of smog are thought to be large factories, but the smog squad will enforce many regulations aimed at individuals, such as the use of barbequesLWYang / Flickr