Liu Zhiqiang shows the theory chart. [Photo/dahe.cn]

A son spent six years developing an anti-smog machine because his mother was suffering respiratory ailments in Zhengzhou, Central China's Henan province, dahe.cn reported on Friday.

Liu Zhenqiang, a 60-year-old native of Zhengzhou, began to study air purification in 2008, when his mother had pneumonia which later turned to asthma on heavy smog days. In 2010, his mother suffered from shock due to smog and nearly died.

According to Liu's design, the machine valued at 100 million yuan ($ 16.3million) is composed of a 150 to 300-meter-long pipe thrust into the air, a ventilator and a scrubber to extract dust and sulfur dioxide from polluted air. The purified air is discharged and can be used as material to make fertilizer.

At least one expert has said the machine is not practical.

Related: APEC car restrictions eyed for long-term use