The U.S. Environmental Protection Agency has announced plans to collect indoor air samples from homes downstream of an Exxon Mobil oil spill that’s leaked as much as 42,000 gallons of crude oil beneath Montana’s Yellowstone River. The Exxon Mobil Pipeline Company initially downplayed the incident, saying it would only affect 10 miles of the river, but state officials say the spill has already stretched more than 240 miles to near the North Dakota border. Local residents have raised concerns over health risks and reported symptoms including nausea, dizziness and shortness of breath.