The U.S. Environmental Protection Agency announced Monday Terre Haute and the rest of Vigo County now meets the National Ambient Air Quality Standard for sulfur dioxide.

This follows Duke Energy closing its Wabash River coal plant, near West Terre Haute.

Janet McCabe of the Environmental Resilience Institute says it’s important to make sure good air quality is maintained. Of the two locations that were monitored in Terre Haute, over a three year average, one barely met the quality air standard and the other tested well.

“One of the things that EPA has to determine as part of this is that the reductions that have improved air quality are permanent, that is that they’ll stay in place, and enforceable,” McCabe says.

McCabe says all businesses that will emit a lot of pollution must get permits before they build. In areas with bad air quality, businesses face stricter restrictions, because no new pollution can be added. In areas like Terre Haute that have been redesignated, permits go back to normal limitations.

According to the Indiana Department of Environmental Management, this is the second Indiana county to meet the same standards in the last few years. After Indianapolis Power and Light Company’s Harding Street facility switch to natural gas, Marion County met the same standards.

IDEM has submitted a request to redesignate Morgan County to attainment, and expects that decision to be finalized before the end of the year.