"Beijing is experiencing a warm, dry winter so sands can easily be stirred up. If the present weather continues, then severe sandstorms are likely in the spring," said Shi Hanmin, head of the municipal Environmental Protection Bureau.

    Beijing has experienced two snowfalls this winter and the temperature on sanjiu days, a traditional term for the coldest days of the year, stood at minus 1.3 degrees Celsius, the warmest for 13 years.

    Last year, the city reported 241 so-called "blue sky days", or days with fairly good air quality, when particulate matter in the air is less than 100 micrograms per cubic meter, according to the environmental bureau.

    "It is hard for us to improve on 60 percent of blue sky days per year. We don't have many new solutions to combat dusty weather," Shi said.

    But he said Beijing will renovate more than 1,100 coal-fuelled boilers and replace 2,580 old buses by the end of the year in further anti-pollution efforts.

    "Also, next year, the city will apply Euro IV emission standards to new vehicles to cut automobile pollutants," Shi said.

    In the event of sandstorms, city authorities will ask roadside stores, companies and other institutions to sweep the dust from streets and roofs so as to prevent further air pollution, he said.

    Beijing experienced 17 sandstorms last spring, and the most serious one in April saw some 300,000 tons of sand and dust dumped on the city.