The new round of inspections follow checks that were made earlier this month, in which inspectors found several factories emitting large amounts of pollutants in the city of Xinxiang, during the air pollution alert period.
This time, the inspectors found Yubei Chemical Ltd, one of the companies that had failed to pass the last inspection, had suspended its production.
City official Li Zhongyao says steps are being taken to cut pollution at its source.
"We have drawn inferences about other cases from one instance and checked the city's enterprises one by one. We will resolutely rectify problems once we find them."
Various measures have also been carried out in northern and eastern China as heavy smog lingers.
