BP Plc said it was monitoring the situation after a small pipe at the Whiting Refinery tank field in Indiana developed a leak, causing an emergency response and odors that were detected as far away as Chicago, the company said in a Dec. 27 statement.

BP said emergency crews have stopped the leak and the refinery was back to normal operations.

"BP is monitoring air emissions for elevated levels of contaminants that could pose a risk to public health," the company said in a release.

The leak originated on Dec. 26, releasing a liquid that may have been responsible for the odors, Reuters reported.

The Whiting Refinery, with a capacity of 440,000 bbl/d of crude, is the largest in the Midwest and produces several liquid fuels, according to BP.

Whiting Refinery
(Source: Rextag)