Chen's system has inspired others to revamp their homes, including not only his friends but also a European who read media reports about it. The man contacted Chen for

"I told him how to install the system, and he hired workers to do it," Chen says.

Chen is among a growing number of grassroots designers in China who are creating innovative and DIY solutions to smog. But he stands out in that many tinkers are focusing on filtration - i.e., high-efficiency absorption filters taped to the fronts of fans - rather than ventilation.

Some environmental experts have expressed doubts Chen's system could filter out PM2.5 - particles with diameters smaller than 2.5 microns that the respiratory system can't block.

The World Health Organization recently named air pollution, and especially PM2.5, as a leading environmental cause of cancer deaths.

Chen says more tests need to be done to answer the small particle question.

But he points out his system is cost-effective.

"Only purifiers used by the semiconductor industry can completely filter PM2.5," he explains.

"But they're very expensive. Installing those in homes would be like using a cannon to blast a mosquito. We need more research on which filters effectively fight PM2.5 so we can clear these particles from our homes."