Beijing has been shrouded in fog for four days and the weather will continue for the coming three days, according to experts at the Beijing Meteorological Station.

However airlines and expressways have not been effected by the thick fog.

Beijing is used to having fog in late autumn, but a fog lasting so long is rarely seen, according to experts. They believe there are two main reasons for the fog.

One is that Beijing has had more rainfall this month than that of the same period of previous years. The city has accumulated 30 millimeters of rainfall in October so far, in contrast with an average of 20 millimeters over the same period of previous years.

The other reason is that pollutants are not being diffused because the air is staying inert without much wind.

Continuous fog has degenerated the city's air, according to Beijing environment protection experts. And citizens are advised to avoid outdoor activities.

(Xinhua News Agency 10/25/2001)