Equipment failure led to a release of pollutants at the Tengizchevroil enterprise in Kazakhstan, according to Kazakhstan’s ecology, geology and natural resources ministry.

Kazakhstan’s biggest oil producer, Chevron-led Tengizchevroil (TCO) develops Tengiz and Korolevskoye oil and gas fields Atyrau region, the energy industry hub in western Kazakhstan.

“Due to a failure of the automatic blocking equipment through the chimney, pollutants were released into the environment at the Tengizchevroil LLP,” the ministry said in a press release.

It said that no one was hurt and the emission of harmful yellow smoke into the environment was stopped within ten minutes. It was not clear where exactly pollution took place.

Chevron-led Tengizchevroil, in which U.S. Exxon Mobil, Russia’s Lukoil and Kazakh state firm KazMunayGaz also have stakes, accounts for almost a third of the Central Asian nation’s total oil output. It is currently implementing the Tengiz production expansion project with a total cost of $ 45.2 billion. The project is to be completed by the end of 2022.