The American Cancer Society and the World Lung Foundation say tobacco use killed nearly six million people last year and smoking is the leading cause of death in China, which is the world’s largest market for cigarettes.

The two organizations released a report in Singapore explaining that four out of five smoking-related deaths occur in low- and middle-income countries. They predict that smoking or exposure to second-hand smoke will kill a billion people during this century if the trend goes unchecked.

The report said that the number of smoking-related deaths has tripled over the past ten years.

It also said that China is the world’s largest producer and consumer of cigarettes. China accounted for 38 percent of global tobacco consumption in 2009.