Flaring occurred Wednesday evening at the Chevron refinery in Richmond because a process unit was upset, Chevron officials said.
As of 9:22 p.m., the flaring had stopped after employees addressed the cause, Chevron spokesperson Amy Mosley said.
A Community Warning System Level 1 was issued because flaring was visible. On the CWS scale, Level 1 is one of the lowest, Mosley said.
The flaring was not a threat to the health of residents or the environment, according to Chevron.
Mosley said flaring helps keep the refinery running safely by relieving pressure in the refining process.