Hulun Buir City and its neighboring areas in north China's Inner Mongolia Autonomous Region has been engulfed in haze from forest fires in Russia.
Covering 253,000 square km in the northeast of the region, the rural part of the city shares a 1,048-km border with Russia.
The visibility is about 1,000 meters in the city, and the haze showed no signs of dispersing on Wednesday.
Zhao Kexin, president of Hulun Buir Observatory, said the smokewas caused by forest and grassland fires in neighboring Russia.
Hazes were also reported in Arxan City in the region and Qiqihar City in Heilongjiang Province, northeast China.
Zhang Guojun, vice-director of the Fire Control Office of HulunBuir city government, said satellite images indicated fires in border areas in Russia were out of control.
The official said fires which spread to Chinese border areas had been put out.