Cars edge along the Gonghexin Road Overpass as a rare heavy fog blanketed Shanghai yesterday. On Thursday night, when the fog began spreading again, it cut visibility to less than 400 meters in downtown.

Armed policemen help a man and his bicycle onto a truck yesterday. With the city's ferries suspended because of fog, soldiers were out helping commuters through the tunnels.

Traffic on water, land and in the air was seriously disrupted by fog and weather yesterday - and forecasters say an approaching cold front could even bring snow to?Shanghai this weekend.

Labeled by local meteorologists as a "disaster," fog settled on the city again on Thursday night and the Shanghai Meteorological Bureau issued an orange fog alert at 10:15pm which remained in place until 2:50pm yesterday afternoon.

A strong cold front is expected to hit the city early this morning bringing low temperatures, rain, and possibly snow. The temperature will drop eight to 10 degrees Celsius within two days to a low on Monday or Tuesday morning of zero to two degrees. It will be one degree below zero in the suburbs, the weather bureau said.

Visibility in the city was reduced to less than 400 meters when the fog started to spread on Thursday night. In the worst-hit suburban areas it was less than 100 meters, Shen Lifeng, a senior engineer from the weather bureau, said yesterday.

The lingering fog has forced the bureau to issue six warnings, the first time in a decade.

The city's airports have suffered continuous interruptions to their schedules.

A total of 340 scheduled flights could neither land nor take off and around 60 were cancelled at Pudong International Airport yesterday.

Not just passenger flights but freight and mail have also been affected.

"Many shipments have been delayed by the disruptions and that affects customs documents as well. I have to rearrange shipments for the weekend. I am calling the shippers again and again to confirm the arrival of shipments as well as calling the airlines to change bookings," said Summer Zhao, a customer service agent for a foreign air logistics company in town, one of thousands kept extremely busy by the side effects of the fog.

Two major goods delivery service providers, FedEx and UPS, said they could not be sure about times for airmails as long as the fog stayed around.

"Many airmail parcels and letters will arrive later than scheduled by at least one day," a client service representative of FedEx said.

The city's children's hospitals said more patients suffering respiratory diseases have been seeking help.

Officials from the Shanghai Children's Medical Center said the demand for its outpatient and emergency services increased by 20 percent and the center treated 3,000 patients a day.

"Many of the patients have respiratory diseases. Because children go to school early in the morning when the fog is thick, it is likely to result in asthma, allergy syndromes and colds," said Dr Yue Mengyuan, director of the hospital's out-patient department.

Yesterday's heavy fog was a concern for students from Chongming Island who were heading downtown for the national college entrance exam's painting test today - a test which could affect their college admissions.

By 11am yesterday, about two-thirds of the examinees had left the island and had reached the exam hall.

Education officials said that they would set a different exam for those students who couldn't reach the exam hall and the students did not have to panic about leaving the island.

(Shanghai Daily January 12, 2008)