The northern part of the country, including Beijing, continues to experience heavy smog that has persisted since last weekend. CCTV Reporter Li Nan has the story.

Vehicles run on a fog shrouded road in Jinan, capital of east China's Shandong Province, Dec. 6, 2011. Many areas in China witnessed heavy fog on Tuesday. The visibility in some areas were less than 200 meters. [Xinhua]

Dense smog has shrouded Beijing since Sunday. Visibility dropped to as low as 500 meters in some parts of the capital, disrupting hundreds of flights. Many highways have also been closed due to the poor visibility, as drivers have had to keep their lights on even at noon. But the issue has not been limited to the capitol.

The weather front has led many to worry about possible health implications, and some have chosen to wear masks outdoors.

I think it is an environmental problem. The haze has been inconvenient for drivers. It has also affected public transportation, such as light rail and buses.

I'm not worried about the smog itself. I'm more concerned about whether the particles in the smog will cause health problems.

China's Central Meteorological Station has paid great attention to the recent weather.

The station issued several code yellow alerts for heavy smog during the past few days. Ma Xuekuan, the chief forecaster, explains its cause.

Ma Xuekuan, Chief Forecaster of Central Meteorological Station, said, "A lot of areas in Northern China have maintained high humidity recently. As a result, fog has formed during nights when the temperature drops. Meanwhile, there is normally not much wind during hazy days. Therefore the fog can suspend small particles in the air, which makes the situation worse.

Ma Xuekuan suggests children and the aged should avoid outdoor exercise during the current weather. He also believes that the haze over Northern China will clear in a few days.