BEIJING -- Polluted air was reported in 163 cities across China as of midday Wednesday after air pollution reared its ugly head Tuesday, the Ministry of Environmental Protection (MEP) announced.

Tangshan in Hebei Province, and Fuyang in Anhui Province were the most polluted cities. Another 21 cities, including Langfang and Tianjin, all reported "heavy pollution."

Beijing was also heavily polluted with an hourly average density of PM 2.5, particles that causes hazardous smog, hitting 190 micrograms per cubic meter.

Luo Yi, an MEP official in charge of surveillance, said the latest round of air pollution began Tuesday when the average density of PM 2.5 and PM 10 in 338 cities under surveillance surged by 17.6 percent and 11.7 percent, respectively, from one day before.

The affected cities are mainly scattered around the northern Beijing-Tianjin-Hebei; southwestern Chengdu-Chongqing; northwest and southern Guangdong-Guangxi regions, Luo said.

Air pollution in the Beijing-Tianjin-Hebei region will remain until Friday night, when weather condition favorable to disperse pollutants have been forecasted, according to forecast.