U.S. President Donald Trump's administration has ordered a halt to research on the potential health hazards of people who live near mountaintop coal mining operations. The U.S. Interior Department ordered the National Academies of Sciences, Engineering and Medicine to end a study of surface coal mining sites in the Appalachian Mountains, pending a review of projects that cost more than $100,000. Last year the Interior Department, under then President Barack Obama, commissioned research into possible health risks among those who live near current or former mining sites in Appalachia. The agency allocated $1 million in 2015 for a two-year study at the request of officials from West Virginia, located in the heart of Appalachia. But the Interior Department ordered an immediate halt to the research, defending it as necessary to ensure the responsible expenditure of taxpayer money. Trump proposed a $1.6 billion cut to Interior's budget in 2018, including 4,000 jobs. The decision, which took effect Monday, comes as the Trump administration and Republican lawmakers collaborate to eliminate policies they believe restrict the mining and use of coal. Trump promised during his presidential campaign to create jobs by reviving the coal industry, and signed an executive order in March that lifted a ban on leases for mining coal on federal land. Environmentalists maintain the removal of coal from mountaintops releases pollutants into water and air, causing numerous health problems such as cancer, cardiovascular disease and birth defects. Indiana University health science professor Michael Hendryx told House lawmakers in 2015 that his studies have connected mountaintop removal to higher rates of lung cancer, heart and kidney disease and other illnesses. The Sierra Club's Appalachia organizer, Bill Price, described the decision as "infuriating." "Trump has once again shown the people of Appalachia that we mean nothing to him," he said in a statement.