China's environmental watchdog on Wednesday identified two cities in central China's Henan Province as the origin of the latest round of smog that has shrouded north China since Tuesday.
Smog emerged in Anyang and Zhengzhou on Tuesday and reached the "heavily-polluted" level on Tuesday night, the Ministry of Environmental Protection said in a statement.
Carried by wind, the pollution spread to the north along the Taiheng Mountain to reach the Beijing-Tianjin-Hebei region, said the ministry.
The ministry said Anyang city has significant problems in air pollution control.
"Emergency response measures were not strictly enforced, for example, the Anyang Iron and Steel Group discharged pollutants exceeding limits set by authorities, even if a first-degree smog alert was in place," noted the statement.
Some enterprises were providing false on-line pollution monitoring figures and the city government had not done enough to curb pollution by small enterprises, the ministry said.
The government had been slow in action or not acting at all, according to the ministry. It said government agencies in Anyang gave conflicting directives to businesses, which resulted in a failure to halt production by some enterprises.
The ministry predicted the smog in the Beijing-Tianjin-Hebei region and neighboring cities will abate starting Wednesday night.