Beijing issued its first smog alert of 2015 on Tuesday, with the PM2.5 index passing the 200 level.
The alert will probably remain in force until Friday, the municipal environmental authority said.
Based on the official daily air quality forecast, the capital issued a yellow alert and adopted emergency measures to rein in emissions on Sunday, one day before the smog descended. A yellow alert is the third-highest level among four grades.
Shanghai, which emerged from three days of smog on Monday, will experience another round of air pollution on Wednesday, according to the regional air quality forecast centre.
The air quality forecast, which is as important as the daily weather forecast, has begun to attract more attention, especially from people living in large cities like Beijing and Shanghai, which witness frequent air pollution.
By the end of 2014, cities in three major industrial zones - the Beijing-Tianjin-Hebei area, the Yangtze River Delta and Pearl River Delta - were required to provide a daily air quality forecast, according to the Ministry of Environmental Protection.
This will be expanded this year to more cities that have the requisite equipment and technology.
Beijing, one of the first cities to issue such forecasts, can predict changing air quality over five days. This enables it to provide accurate statistics for the authorities to take emergency measures to reduce air pollutants a day before smog arrives.
Xie Shaodong, an environmental professor at Peking University, said: "The technology is not a problem. With better cooperation and smoother exchanges of information between meteorological and environmental bureaus, the forecast can be more accurate."
Yu Yong, a spokesman for the National Meteorological Administration, said it plans to deepen cooperation on air pollution forecasting through regular discussions and exchanges of technology.
According to a development plan released on Dec 17 to help control air pollution, the meteorological administration will build more laboratories in six regions to strengthen weather forecasting by 2020.
Under the plan, by that year China will have built a well-functioning weather modification system and have made progress in experiments on reducing fog and smog through human effort.