Oil giant BP has agreed to pay a $512,450 penalty and reduce soot emissions from its Whiting refinery in Indiana. The company reached a consent agreement Thursday with regulators and activists who accused the company of violating an earlier deal.

The sprawling facility is on the southwestern shore of Lake Michigan. Its high-temperature processing units release tiny “particulate matter,” or soot, which is linked to asthma and other respiratory and cardiovascular illnesses.

The refinery is 15 miles southeast of Chicago. It’s the largest in the Midwest and the sixth-largest in the U.S.