SHIJIAZHUANG, Dec. 13 -- A smog-bothered Chinese school has turned to the country's traditional kung fu for self-defense against polluted air, although the method's effect has been widely doubted.

Guangming Road Primary School in north China's Hebei Province, has designed a set of kung fu aerobics which are claimed to mitigate the effects of smog on the human body.

They consist of 23 moves, with two of them, pressing an acupoint called Hegu and breathing into the belly, being particularly effective against air pollution, said Wei Huanqiang, deputy dean of the school in the provincial capital Shijiazhuang, one of the Chinese cities worst hit by smog.

"Pressing the Hegu acupoint, located between the thumb and index finger at the back of the hand, helps promote lungs' detoxification. Breathing into the belly dispels more residue gas left in human organs, reducing the harm caused by smog," he said.

Wei designed the moves in September and October. They can be performed in the classroom, helpful considering China's smog often forces the school to cancel outdoor exercises.

Students will sweat a little after the whole set of exercise, taking about two minutes, according to Wei.

In recent months, heavy smog has shrouded north and east China intermittently, with schools and highways closed and flights delayed or canceled in extreme cases.

"The smog particles inhaled in our lungs are harmful, and we have to wear mouth cover on our way to school or home. We were taught that the aerobics help us to get rid of the dirty particles," said He Linxuan, a fourth-grade student.

The school, famous for its martial arts classes, has 470 students. All of them are required to do the aerobics four times daily on smoggy days.

The supposedly anti-smog kung fu has drawn wide controversy. Although some Internet users have remarked that indoor exercises can indeed be healthy for children, many others have poured scorn on the idea that a few simple moves can be used to resist the effects of polluted air.

Liu Erjun, a doctor with the traditional Chinese medicine department of the First Affiliated Hospital under Hebei Medical University, said pressing the acupoints involved in the aerobics helps enhance people's immune system, but it is unclear how much help it will be in stopping smog-related illnesses.