China’s got a soil pollution problem. Some estimates have suggested as much as 70 percent of the country’s soil has been contaminated. As you might guess, the government’s data on this matter can be difficult for the public to access. Enter Liu Chunlei. With the financial help of Internet company Alibaba, Liu has been crowdsourcing so-called “Danger Maps” to make the information widely available. He joins Marketplace Tech host Ben Johnson to discuss. Click on the audio player above to hear more.