The Sinclair refinery in Evansville violated the Wyoming Environmental Quality Act by repeated excess releases of toxic hydrogen sulfide, according to a civil lawsuit filed by the Wyoming Attorney General's Office in Natrona County District Court.

The refinery's flare had released more than the maximum allowable amounts of the chemical more than 50 percent of the time on a three-hour rolling average from January through March 2016, according to the Attorney General's Office, which represents the Wyoming Department of Environmental Quality's air quality division.

The Department of Environmental Quality issued a notice of violation to the refinery on Aug. 9, 2016, about violating air quality rules.

Each failure to properly combust fuel gas under U.S. Environmental Protection Agency standards is punishable by up to $10,000 for each violation, according to the lawsuit filed April 24 entitled "People of the State of Wyoming v. Sinclair Casper Refining Company."

The lawsuit did not explain the delay of filing the notice of violation in 2016 and the filing of the lawsuit in April.

When incinerated in a flare, hydrogen sulfide creates sulfur dioxide, according to the lawsuit."Sulfur dioxide is a rapidly-diffusing reactive gas that is emitted when combusting or process sulfur-containing fossil fuels and ores."

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"Sulfur dioxide is more likely to have harmful effects on people with pre-existing respiratory disease or genetic susceptibility to respiratory disease, young children, the elderly, people who spend a lot of time outside, people who have increased ventilation rates, and people with limited access to health care," according to the lawsuit.

The state wants district court to find that Sinclair violated the EPA rule about monitoring hydrogen sulfide emissions, order it to comply with the rule, pay a civil penalty up to the maximum of $10,000 for each day of violation, and mitigate pas excess emissions of sulfur dioxide, according to the lawsuit.

Wyoming Assistant Attorney General Kelly Shaw, who filed the complaint against Sinclair, declined to comment.

Likewise, David Stice, attorney for Sinclair Oil Corp., at its Salt Lake City headquarters, declined to comment.