Beijing is struggling to cope with thick smog for the fourth time within a month. Severe air pollution has prompted the Beijing Municipal Government to control car emissions and temporarily shut factories. But experts say long term measures are needed to address the root cause of the pollution.

Thick smog has shrouded Beijing, and blue skies are a rare sight. The density of PM2.5 particles in the air has surged in many cities across north China. Experts say there are three major sources of the PM2.5 pollutants.

Shao Min, vice president of College of Environmental Science, Peking University, said, "First of all, there are too many cars on Beijing's roads, and the number of cars is growing too fast. Road congestion is also a major problem, causing serious exhaust emissions. Industry emissions and the dust from construction sites exacerbates the problem."

Beijing has implemented stricter regulations to control car emissions. Cars that discharge pollutants in excess of the prescribed norms will be fined up to 3,000 yuan ($482.1). Meanwhile, the city government has ordered 103 heavily polluting factories to suspend production. The measure will last until Thursday. But experts say temporary measures won't control the root of the problem.

"We need a coordinated solution that controls multiple pollution sources. It won't make a difference if we only control exhaust or industry emissions. It's also important to expand pollution control efforts to the entire northern region," Shao said.

Coal-fired heating in Beijing is also blamed for the worsening air quality. Beijing is striving to be coal-free, planning to cut coal burning from 20 million tons to 15 million tons by 2015.

Much is needed to be done before blue skies return to the capital. The city government is urging citizens to drive less, and do their bit to improve the air quality.

(CNTV.cn January 30, 2013)