Barely two weeks after the first heavy fog of this winter hit most parts of China on Dec. 2, many expressways are closed again Tuesday as another one is looming over several cities.

The nation's capital Beijing temporarily closed its suburban sixth ring road early Tuesday as visibility dropped below one kilometer. Two expressways linking Beijing with neighboring Tianjin municipality and Hebei Province were also partially closed.

Officials with Beijing's transportation bureau said road traffic in the city proper was largely unaffected, though more people were opting to travel by bus or subway instead of driving their own cars.

The Beijing public bus company and the subway operator are ready to send more buses and trains when the passenger flow speeds up during the rush hours, sources with the bureau told Xinhua.

By press time, there has been no report of flight cancellation or delay at the capital airport, and railway authorities say all incoming and outgoing trains are on time at the two major railway stations. But meteorological experts predict the foggy weather will linger a day or two, until a cold current dispels the pollutants on Thursday or Friday.

In Chengdu, capital of southwest China's Sichuan Province, heavy fog has delayed more than 30 flights and laid over several thousand passengers at Shuangliu Airport, where visibility was less than 100 meters at 3:00 a.m. Airport authorities say flights will not resume normal before Tuesday afternoon.

Sources with the city's meteorological station said the airport was the worst affected region in the thick fog that was shrouding most parts of Chengdu.

The local road transport authorities closed all major expressways early in the morning, including the expressways linking Chengdu with neighboring Chongqing municipality, and the cities of Ya'an, Mianyang and Nanchong.

Dense fog has been looming over China's largest city Shanghai since Saturday. At 7:06 a.m. Monday, the local meteorological station forecast visibility would drop below 50 meters in some suburban locations including Baoshan, Minhang and Jiading.

At least 40 flights were delayed Monday at Hongqiao Airport, though flights in and out of Pudong Airport were not affected. Major expressways linking Shanghai to other provinces were closed as well.

The fog also affected water transportation in Shanghai. Four water passages in the Songjiang and Minhang districts were closed from 5:30 a.m. to 7:10 a.m. Monday.

The daily report on air quality in 47 major Chinese cities released by the China Environmental Monitoring Station on Monday shows that 19 cities are polluted as the particulate matter in the air has increased drastically in the past three days.

As the dense pollutants in the misty air may affect the respiratory system, health experts have advised the elderly, children and patients of respiratory disease to avoid outdoor exercises or wear masks.

(Xinhua News Agency December 15, 2004)