According to a new analysis by U.S. House Democrats, an increasing percentage of coal from mountaintop removal mines is being exported overseas. The report was released this morning, as the House Natural Resources committee held a hearing on a proposed stream buffer rule to protect Appalachian streams from coal mine pollution.

The report is called “Our Pain, Their Gain,” and was prepared by the committee’s Democratic staff. It’s being promoted by environmental groups as proof that surface mining is a greater benefit to other countries than the United States, where it hurts Appalachian communities.

“American families are being subjected to coal mine pollution and damage, just so exports to China and other foreign nations can increase,” said ranking Democrat Edward Markey of Massachusetts in a release that accompanied the report. “The coal may be shipped to foreign markets, but the diseases, the destroyed mountaintops, and the environmental ruin from these destructive practices are staying right here in America.”

The data shows that coal exports are on the rise. More surface mines export some coal overseas, and the share of production that’s being exported is increasing, too. Several operations—mostly in Pennsylvania and Virginia—are shipping nearly all of the coal mined to other countries.

Most of the coal being shipped overseas is metallurgical coal: coal that’s used to make steel. That’s in demand as countries like China and India are developing. But some thermal coal—which is used for heat—is exported too.

Coal exports have doubled since 2009, but it’s important to note that as a whole, exports still only account for 12 percent of all the coal mined in the U.S. And while those fighting surface mining see the report as vindication that Appalachian communities are suffering to help power China and India, the coal industry argues that coal exports are strengthening the industry as American electricity is moving toward natural gas.

“The complaint here seems to be that other countries are getting the economic benefit of coal,” Kentucky Coal Association President Bill Bissett said. “Well, in that respect, I do agree with Congressman Markey. The United States should get more of the economic benefit from coal, and coal usage does make sense economically.”

Bissett says half of the coal in eastern Kentucky is surface mined, but the vast majority of the coal produced in the state stays domestic.

Besides environmental effects, recent studies have linked surface mining to health problems like cancer, respiratory diseases and birth defects.