BEIJING - The Ministry of Environmental Protection has ordered reinforced measures against the smog while lauding the prompt response in the hazy capital.

The ministry on Tuesday sent two teams to central China's Henan Province to inspect measures to cope with the severe pollution.

It had previously dispatched 10 inspection teams to regions known for heavy pollution, mainly around Beijing, to ensure emergency plans were in place. The teams also monitored known polluters, such as those that burn coal and high-emission vehicles.

Beijing on Tuesday morning issued a red alert for air pollution, its highest level, which will last until 12 noon Thursday. The warning means suspension of classes, construction work and limited use of cars.

Environment Minister Chen Jining praised the timely manner in which the alert was issued.

"Environment authorities must closely follow the situation, improve monitoring and forecasting, and guide local governments' emergency response plans," he said at a press conference.

Chen said the warning levels should be adjusted according to the real-time pollution conditions.

He also asked local authorities to be transparent and to keep the public up-to-date.