Severe weather caused BP’s Whiting Refinery to send more pollution into the air Sunday night. Local emergency management officials believe that could be what’s causing a sulfur smell in several counties in northwest Indiana.

Officials in La Porte County first thought it was a gas leak, but the utility didn’t find any. And later nearby Porter County also started getting overwhelmed with 911 calls about the smell. Lance Bella directs the Porter County Emergency Management Agency.

“It smelled like sulfur, didn’t smell like natural gas and almost smelled like an oily smell. So I started checking with our local industry,” he said.

Power outages disrupted operations at the Whiting Refinery causing unplanned gas flaring. That’s where excess natural gas produced during oil refining is burned off into the atmosphere.

Flares are supposed to reduce most of the pollutants in natural gas, but they can still release things like sulfur dioxide — which can harm your lungs and make breathing difficult, especially for people with lung conditions. Flaring can also release carbon dioxide and some methane — greenhouse gasses that contribute to climate change.

READ MORE: BP to pay record high penalty for air pollution at its northwest Indiana refinery

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BP has said the community is safe, but local health officials and the Indiana Department of Environmental Management haven’t confirmed that. The company said no injuries have been reported.

Bella said once Porter County EMA learned about BP’s excess flares, it contacted IDEM and the local health department. He said so far, officials with northwest Indiana counties haven’t found any other evidence of industrial leaks or spills that could have caused the smell.

In a statement Monday morning, BP said it was monitoring the situation and it expects it to resolve itself in a few hours.

Last month, the refinery received the largest federal penalty ever imposed for industrial air pollution in U.S. history.

Rebecca is our energy and environment reporter. Contact her at rthiele@iu.edu or follow her on Twitter at @beckythiele.