An investigation has been launched by oil major Chevron after black smoke could be seen as a result of flaring activity from its Richmond refinery in the US.
The company said the surrounding community had been informed of the smoke on Saturday at around 8.40am via its warning system.
A spokeswoman for the company said It was “actively investigating” the incident.
Anyone concerned about the air-quality following the flaring activity has been told to contact the Richmond Community Air Monitoring Program.
In a statement the company said: “Flaring is an important part of keeping the refinery running safely.
“Flares are a safety device used in refineries to relieve pressure during the refinery processes and help keep our equipment and plants operating safely.”