A Chevron oil refinery in Richmond, California is now under investigation by the Environmental Protection Agency over claims that the site has been illegally burning off toxic pollutants, according to the San Francisco Chronicle.

The EPA opened a criminal probe earlier this year following allegations by the Bay Area Air Quality Management District that the refinery has been funneling pollutants away from a chemical monitoring system and instead incinerating the pollutants in an unmonitored gas flare, sending dangerous toxins into the air, towards the downwind city of Richmond, Calif.

As a result federal monitors would not have been able to gauge the actual amount of pollution that is bellowing from the plant.

The chairman of the Bay Area air-quality district's board, Contra Costa County Supervisor John Gioia, said that the actions raised "extremely serious" questions about the company.

Federal regulations are "designed to reduce flaring, and refineries are supposed have a responsibility to abide by it," Gioia stated. "That's a criminal act, intentionally bypassing the monitoring."

Earlier this year the same Chevron refinery made news when a massive blaze broke out at the site, causing a plume of toxic smoke to subsequently enshroud the Bay Area. Thousands of people were treated in hospitals in the pollution plagued area of Richmond. Chevron was criticized for its stunted response to the gas leak that lead to the massive blaze, which burned for more than four hours with flames reaching 40 feet in the air.