ZHENGZHOU - The principal of a middle school in Central China's Henan province has been suspended from duty.

In Linzhou city, all kindergartens and schools in the city were told to close on Monday, and stay closed until the end of this week's red alert for air pollution.

But instead of staying home, more students of Linqi Township No 1 Middle School were summoned for exams. More than 400 of them turned out for exams staged in the school playground -- English and math in the morning, Chinese language and physics in the afternoon -- despite the worst pollution of the year on Monday.

The city education and sports bureau have since suspended the head of the school for organizing the outdoor exams for hundreds of students.

Northern China has been suffering this week under the worst smog of the winter so far.