Miami, FL, United States (AHN) – Coal that wiped out almost all life on the planet 250 million years ago may still be killing people in China, scientists say.

David Large, a professor at the University of Nottingham’s department of Chemical and Environmental Engineering, said in a statement that the high silica content of coal in China’s Xuan Wei County in the Yunnan Province could be responsible for the area’s reputation as having the world’s highest lung cancer rate among non-smoking women.

The region’s lung cancer rate is 20 percent higher than the rest of the country.

Women there heat their homes and cook food in coal-burning stoves that are not vented to the outside, Large said.

Coal in Xuan Wei County has about 10 times more silica than coal mined in the United States. Silica is a suspected carcinogen, or cause of cancer. The coal was formed more than 200 million years ago and its emissions are thought by scientists to have spread by a massive volcanic eruption and to have killed more than 70 percent of the world’s plants and animals

Large’s report is published in the journal, Environmental Science & Technology.