Where is the most polluted place on Earth?

In November 2013 it was revealed that an 8-year-old girl living in China’s Jiangsu province had become the country’s youngest lung cancer patient, with doctors pointing to China’s high levels of pollution as the cause. This shocking piece of news got us thinking about how China fares compared to other countries when it comes to pollution. All of the media focus makes it seems like the most polluted place on earth but is that really true? Or could there be other contenders out there?