Dense smog has shrouded many parts of northeast China's Jilin Province since Oct. 30. The air quality indexes from many monitoring stations in Changchun, the capital city of Jilin Province, hit the maximum of 500 between 5 p.m. and 8 p.m. yesterday. According to the Ministry of Environmental Protection, air pollution is "serious" when AQI is between 301 and 500. [Photo/Xinhua]